Hello all. When driving my 71 CDV above about 60 mph I hear a vibration coming from the front of the vehicle. Under load going up a hill is much more
prevalent. Letting off the gas makes the sound go away. It is a slowly oscillating vibration. Waw...... waw.......waw.......
I have a car lift and I put the car in the air and ran it up to 70 mpg briefly and could not hear the noise. The front wheels spin freely and I cannot hear a bearing noise when I spin them by hand. The rear diff gears look good as I check in the diff last night.
I am thinking that this is a vibration coming from the engine. Maybe a bracket is hitting something under load when the engine is providing torque.
Both motor mounts and the transmission mount are new. The AC compressor is also new and works well.
Any thoughts or guidance would be greatly appreciated. The driving experience is ruined by this sound.
Axle bearing or U-joint come to mind (pull the RH drum and check for oil a worn bearing will manifest itself as an oil leak first)
Bill
A great place to start is the shop manual at the beginning of the book, it has a thorough chapter on vibration and how to isolate it. I think you are most of the way there with the only under load at high speed. There will be suggestions on how to cure this type of problem.
One of my friends suffered a vibration problem and via the shop manual it was diagnosed as a bad fan clutch, no wonder the water pump prematurely failed before.
I presume a 71 uses the 'CV' type of U joints? When those wear they can change behavior depending on load.
I never tangled with them on the Cads but on the trucks if you pulled the shaft assembly and the joint end just flopped loose it was shot. After you got it rebuilt it would just about hold its own weight and stay straight.
bill06447
I've yet to pull off a rear wheel as I have not had this car very long but I will try that.
Scot Minesinger
I just got a shop manual. Good tip. Thanks!
TJ
This is a Deville so it is rear wheel drive. Not sure where you are going with this one.
On my 78 vette the AC compressor belt is notorious for vibrating at certain engine RPMs. This is a common problem for vettes of that time period. The AC belt is pretty long.
As you know there are two belts driving the compressor and the PW pump. I will try to tighten them and see if there is a difference. They seem OK but could be tighter to suite me.
One other thing to note is that this car does not have a clutched fan. I guess what you call it is a flex fan.
It appears to be stock. I don't think the sound is coming from there.
Don't forget to check and tighten all the front end sheet metal, bumpers, bumper mounts and grill.
Greg Surfas
TJ is right. If you remove RWD drive shaft and the "universal joint" end that slips into trans tail with drive shaft on your work bench does not stay in the position you move it to, but flops around always going to where gravity pulls it, then it is shot.
Possibly called a 'double cardan joint'?
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS_qPqCMBdCQ9CTEpcsVFLijMsLx5ONmvd-PwK2Um0zzn67ShK0wA)
Thanks to 4x4shaft.com for the photo. The ones Cadillac often used were not identical to this one but similar.
They are/were commonly used on trucks apparently due to the more extreme drive shaft angles. Cadillac apparently used them due to lack of angle and to make sure things stayed extra smooth. There was a discussion about them a while back and the thought was that rather than place the rear end and engine/trans in the ideal location for the drive shaft to work like most manufactures did Cadillac put them where they needed to be for the rest of the body and styling to work so they gained the look they wanted and 2 more inches of legroom or something like that.
I'm thinking a 71 had them and my point is that they can act a lot different than the regular single joints when they wear.
If the vibration were coming from the driveshaft wouldn't the vibration be much faster than described, like a difference in harmonics? Seems like to me it might be belt or possibly an unevenly running engine or exhaust resonance? Just some thoughts. Larry
I have had the drive shaft out recently because the transmission
tailshaft seal was leaking. I replaced the seal.
TJ
The drive "slip yoke" (which inserts into the transmission)
does move freely about but it does not flop around. It seems
tight enough however.
The double cardan joint as you call it does not flop down. It stays in place
when the drive shaft is lying on my roll-around table. I do not think
there is an issue with the drive shaft.
cadman56
These were my thoughts as well. I am going to make a PS pump tensioning tool, as outlined in the shop manual, and tighten
the PS/Compressor belts to see what the effect is.
This sound is barely audible between 30 and 55 mph......and I mean JUST barely. Then when you get to hwy speeds it begins
a slow oscillation........ waw..........waw...........waw............. were each "waw" is probably one second apart.
I'm on the verge of buying one of those Steelman Chassis Ears.
Quote from: impalaman on February 10, 2016, 10:51:23 AM
This sound is barely audible between 30 and 55 mph......and I mean JUST barely. Then when you get to hwy speeds it begins
a slow oscillation........ waw..........waw...........waw............. were each "waw" is probably one second apart.
I'm on the verge of buying one of those Steelman Chassis Ears.
Is this just sound, or sound and vibration? Sounds to me like exhaust resonance. Is it a stock single exhaust? have you changed anything?
Dan
These are very difficult to solve over the internet. I hope we helped.
Feel very confident you will figure it out. I just use a pry bar to tension power steering belt - you are making a tool-wow! That is a testament to your thoroughness, that is what makes me think you will get the vibration resolved.
Unless a power steering pump pulley is bent or power steering pump is messed this is an unlikely source of the trouble. Have seen very loose and too tight PS belts and it had no impact on vibration.
My father in law always said "it is something simple", and he was right most of the time.
dplotkin
There is a vibration as well but it is not bad. You can feel it a little throught the gas pedal.
Scot
I usually use a pry bar as well but there is nothing I can see to pry on. When I saw
the tool design outlined in the manual I had to have it! I have two other cars with
this type of pump so I should come in handy.
I'm hoping it's not the transmission..... althoughI've never heard a trans make
a noise like this.... but still.
I tightened the belts tonight with the tool. I'll give it a test drive tomorrow.
I'm not hopeful. We'll see.
dplotkin
This car is bone stock except for an after market aluminum radiator that the previous owner installed.
I supposed it might be vibrating against the frame. I can check that.
The exhaust is all stock as well except for a new muffle. It seems to be solid although I've not yanked
on it extensively. LOL.... I will check.
This car was owned by a very long lived fellow and apparently spent some time in storage.
The story from the previous owner was that he old man worked for a Caddy dealer, thus the good
condition of the car. The interior is absolutely original and in fantastic shape. The paint and vinyl top are original as well.
One other question - did you purchase both PS/AC belts at the same time? It used to be you had to purchase a 'matched set' of belts when running multiples on a device. That meant the belts came from the same manufacturing drum. They stopped selling matched sets about mid-way through my tenure of owning a NAPA parts store. Your belts may be the problem. Also make sure the PS pulley is completely at a 90 deg. to both belts. If not, one belt will always have a different tension from the other. Good luck. Larry
Quote from: Scot Minesinger on February 10, 2016, 09:35:32 PM
I just use a pry bar to tension power steering belt - you are making a tool-wow! That is a testament to your thoroughness, that is what makes me think you will get the vibration resolved.
I could never figure out why Lincoln (Ford) added a 1/2" drive cutout to their brackets to make belt adjustment a simple task with a 1/2" drive ratchet and Cadillac (GM) made one use a pry bar.
Quote from: TJ Hopland on February 10, 2016, 09:29:57 AM
Possibly called a 'double cardan joint'?
(https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS_qPqCMBdCQ9CTEpcsVFLijMsLx5ONmvd-PwK2Um0zzn67ShK0wA)
Thanks to 4x4shaft.com for the photo. The ones Cadillac often used were not identical to this one but similar.
They are/were commonly used on trucks apparently due to the more extreme drive shaft angles. Cadillac apparently used them due to lack of angle and to make sure things stayed extra smooth. There was a discussion about them a while back and the thought was that rather than place the rear end and engine/trans in the ideal location for the drive shaft to work like most manufactures did Cadillac put them where they needed to be for the rest of the body and styling to work so they gained the look they wanted and 2 more inches of legroom or something like that.
I'm thinking a 71 had them and my point is that they can act a lot different than the regular single joints when they wear.
For what its worth, my 72' has that same set up in the picture above. I would think 1971 is the same. Like double ujoints in a special carrier.
Also, impalaman start a new thread and introduce yourself. Your 71' looks beautiful. I would love to see it. Post some pictures of your car. Ive got a 1972 CDV with 28,000 original miles.
-Gavin
Quote from: Jon S on February 11, 2016, 10:54:08 AM
I could never figure out why Lincoln (Ford) added a 1/2" drive cutout to their brackets to make belt adjustment a simple task with a 1/2" drive ratchet and Cadillac (GM) made one use a pry bar.
Amen to that.
Quote from: cadman56 on February 11, 2016, 10:16:23 AM
One other question - did you purchase both PS/AC belts at the same time? It used to be you had to purchase a 'matched set' of belts when running multiples on a device. That meant the belts came from the same manufacturing drum. They stopped selling matched sets about mid-way through my tenure of owning a NAPA parts store. Your belts may be the problem. Also make sure the PS pulley is completely at a 90 deg. to both belts. If not, one belt will always have a different tension from the other. Good luck. Larry
Using the belts that were on the car when I bought it. They look fine but were a little loose for my taste.
I tightened them but the problem remains. I am leaning toward a bearing at this point, although I did not really want to get that deep into it. LOL.... looks like I've no choice.
Bummer. Good luck. Larry
Ok guys I removed the rear wheels and brake drums to make it easy to spin. Check out this video and tell me what this noise is. The transmission is in park.
I've replaced rear axle bearings before but I am not a diff expert by any means. Please listen to this
and tell me what is making this sound.
https://www.youtube.com/watch?v=18PBSFdY4kw
I lowered the car and moved the transmission to neutral. Same noise.
Boy, that diff seems very loose. Or you are very strong.
Never been able to spin an axle as easy as that. The Noise appears to be coming from the sun wheels inside the carrier, and running very dry.
In normal driving, these wheels aren't turning, unless doing a one-wheel-burnout. The whole carrier is turning.
From the noise I am hearing, I would be dropping out the diff centre, and be preparing myself for the sight of a horrible mess.
Axle races are best heard when turning left and right, as in applying load to the sides of the ball bearings/races.
To say that the vibration is only when the power is on and not off, sound like a diff problem. And further seeing the way you can turn the axle so easily, I am thinking that there is very little side pre-loading on the Differential side bearings.
Bruce. >:D
Quote from: The Tassie Devil(le) on February 11, 2016, 08:51:23 PM
Boy, that diff seems very loose. Or you are very strong.
Never been able to spin an axle as easy as that. The Noise appears to be coming from the sun wheels inside the carrier, and running very dry.
In normal driving, these wheels aren't turning, unless doing a one-wheel-burnout. The whole carrier is turning.
From the noise I am hearing, I would be dropping out the diff centre, and be preparing myself for the sight of a horrible mess.
Axle races are best heard when turning left and right, as in applying load to the sides of the ball bearings/races.
To say that the vibration is only when the power is on and not off, sound like a diff problem. And further seeing the way you can turn the axle so easily, I am thinking that there is very little side pre-loading on the Differential side bearings.
Bruce. >:D
Bruce keep in mind that I removed the brake drums so that makes it easier. Also, I just changed the diff gear oil two days ago. While I was in there I rotated it once around slowly and did not see any wear but I don't really know what to look for. Everything looked ok to me.
Regardless of all that..... I should not hear anything like this should I? It should be quiet should it not?
When I raise my 1970 Cadillac and back wheels are off the ground with selector in park, I cannot turn the wheels. Park locks them. The 1970 and 1971 have the same 2.93 ratio and all. I had my differential rebuilt, from video looks and sounds like you may be looking at the same work.
When in Park, the wheels won't turn if the centre is a Limited Slip Diff.
As the wheels shown in the video, the car has an open diff, as the opposite axle is turning in the opposite direction.
Bruce. >:D
Yes. Definitely an open diff on this car. So the question remains..... with an open diff, if you raise the car
in park and attempt to spin the wheels, will they move or not?
When you spin the wheels and hear the sound, do you feel a ticking/ vibration in/on the pumpkinhead? Sure sounds like stuff is flopping around in there. When you spin it like that, 1 gear is turning the other. What happens if you put it in neutral and spin the driveshaft? That would make the load on tbe gears different. Does/will the sound change?
You say you just changed the fluid. Do you still have it (sounds like a stupid question but I always dump stuff in jugs and dispose of it all at once when my wife says I need to get rid of it)? If not then suck out some new fluid and stick a magnet in it. Amy metal?
Jeff
Quote from: impalaman on February 11, 2016, 11:32:11 PM
Yes. Definitely an open diff on this car. So the question remains..... with an open diff, if you raise the car
in park and attempt to spin the wheels, will they move or not?
Yes, but the opposite wheel spins the opposite way, as yours is doing.
Even if not in park, there will usually be too much friction within the Transmission to stop the tail shaft from turning.
Bruce. >:D
In park with no posi diff both back wheels off the ground, I cannot turn the drive shaft, and consequently the wheels do not turn either. When I remove the drive shaft, I am switching from N to P so the bolts are on the bottom for easier access. Cannot leave in N when tightening or drive shaft rotates. N to rotate, P to lock in position to tighten bolts on drive shaft to differential.
It is noisy. Since you are almost there, pull the axles & fell the bearings. I did hear gear chuckle but the 'roar' says bearings to me. Good luck. Larry
I also do not understand why it would spin in Park, but the noise sounds like a bad rear wheel bearing to me as opposed to a rear end noise. Hard to tell without being there.
Quote from: Jeff Rose CLC #28373 on February 11, 2016, 11:56:34 PM
When you spin the wheels and hear the sound, do you feel a ticking/ vibration in/on the pumpkinhead? Sure sounds like stuff is flopping around in there. When you spin it like that, 1 gear is turning the other. What happens if you put it in neutral and spin the driveshaft? That would make the load on tbe gears different. Does/will the sound change?
You say you just changed the fluid. Do you still have it (sounds like a stupid question but I always dump stuff in jugs and dispose of it all at once when my wife says I need to get rid of it)? If not then suck out some new fluid and stick a magnet in it. Amy metal?
Jeff
I will try all of this tonight.
Quote from: Jeff Rose CLC #28373 on February 11, 2016, 11:56:34 PM
When you spin the wheels and hear the sound, do you feel a ticking/ vibration in/on the pumpkinhead? Sure sounds like stuff is flopping around in there. When you spin it like that, 1 gear is turning the other. What happens if you put it in neutral and spin the driveshaft? That would make the load on tbe gears different. Does/will the sound change?
You say you just changed the fluid. Do you still have it (sounds like a stupid question but I always dump stuff in jugs and dispose of it all at once when my wife says I need to get rid of it)? If not then suck out some new fluid and stick a magnet in it. Amy metal?
Jeff
>> When you spin the wheels and hear the sound, do you feel a ticking/ vibration in/on the pumpkinhead?
Yes but I also here and feel it out near the wheels as well. Hard to tell where it is coming from.
>> What happens if you put it in neutral and spin the driveshaft?
I will do this tonight. I assume both wheels will spin the same direction.
Unfortunately no. The fluid is mixed with other stuff in my recycling container.
Quote from: Jon S on February 12, 2016, 10:07:03 AM
I also do not understand why it would spin in Park, but the noise sounds like a bad rear wheel bearing to me as opposed to a rear end noise. Hard to tell without being there.
In speaking with some folks more knowledgeable than I, this is the nature of an open differential. So the scenario is as follows:
- Car on lift, wheels in the air.
- Transmission in park.
- Grab one wheel and attempt to spin.
- You can in fact spin the wheel and the other one will go the opposite direction.
- This is the nature of an open diff. The two sides are not directly tied to one another.
- It is only when a force is applied to the drive shaft, that the wheels will spin the same direction.
I spun the drive shaft by hand and both wheels spun in the same direction as expected. For what it's worth I did not hear anything from the diff. The clicking noise when spinning the wheel is odd. It is coming from the diff. I would expect it to be quiet when you spin the wheel but maybe the ring gear and pinion gear are by some means disconnected under that circumstance (by design).... the the reason the drive shaft does not turn. Also "maybe" the clicking noise is due to whatever mechanism it is that is preventing the drive shaft to turn when you move the wheel. Me not being an expert by any means.... all pure conjecture and a lot of wishful thinking.
Now on the good part. I'm posting photos of the axle bearings and housing. It appears that the pass side was getting hot. Possibly both sides.
Check em out and let me know what you think.
Pass side bearing.
Pass side bearing
Pass side housing. Looks like it got hot.
Quote from: bill06447 on February 09, 2016, 07:39:21 PM
Axle bearing or U-joint come to mind (pull the RH drum and check for oil a worn bearing will manifest itself as an oil leak first)
Bill
Quote from: bill06447 on February 12, 2016, 09:23:04 PM
;)
We'll replace these bearings and hopefully that will be it. If it doesn't I'll take it somewhere and let an expert deal with the diff. Recently replaced rear axle bearings on my CJ so at least I have some practice on that !
The nature of the sounds really through me off. Live and learn.
Looks to me like the outer surface of the races have been spinning within the housing.
Can you spin the outer surface around the axle itself?
Bruce. >:D
It has been a long time since I have has one opened up so I forget the way the gearing is. However since the clicking goes away when the driveshft is turned, that tells me the slop is in the other gears. The driveshaft gear must load those gears up.
Jeff
Quote from: The Tassie Devil(le) on February 12, 2016, 10:15:33 PM
Looks to me like the outer surface of the races have been spinning within the housing.
Can you spin the outer surface around the axle itself?
Bruce. >:D
Yes. The bearings (both pass and drivers) spin but the pass side seems slightly gritty. I won't know the condition until I press it off the shaft.
Get this: Page 4-30 step 6 of the shop manual says to, "Apply a light coat of wheel bearing grease on bearing."
This is in the installation procedure. When I removed these axles, I saw no axle grease.... just rear diff oil. I always assumed you packed axle bearings thoroughly with grease.
My CJ has a seal inward separating the bearing from the diff oil so the bearing has to be greased.
No, the races are already packed from the factory.
I think the factory mention of grease is to make assembling easier, plus easier to remove in years to come. The outer part of the race must not spin.
Bruce. >:D
Where is the seal? This style GM I remember messing with the seal was behind the retainer. To change the seal you had to cut? a retaining collar then you could take the bearing and seal off. New collar had to be pressed on then you could put it all back. I remember the bearings being open on both sides. Seems like the shop I had do mine left the seal on the outside of the bearings when they replaced them so just the inside was open. Fords I remember the seal being the first thing inside then the sealed bearing so no oil got to them at all.
Quote from: TJ Hopland on February 13, 2016, 09:17:20 AM
Where is the seal? This style GM I remember messing with the seal was behind the retainer. To change the seal you had to cut? a retaining collar then you could take the bearing and seal off. New collar had to be pressed on then you could put it all back. I remember the bearings being open on both sides. Seems like the shop I had do mine left the seal on the outside of the bearings when they replaced them so just the inside was open. Fords I remember the seal being the first thing inside then the sealed bearing so no oil got to them at all.
From inboard it is as follows:
1) Stock bearing retainer which sits in a groove. To remove it you have to split it with a cole chisel per the shop manual.
2) The bearing.
3) Seal
4) Backing plate with holes to bolt the axle assembly to the axle housing.
I chiseled off the bearing retainer this morning after I cut the outside of the bearing off with a cutoff wheel. I chiseled off the inside race by tapping on each side, gradually moving it a little at a time. The seal just slips off after that.
The axle looks good. I did notice some hazing on the inside of the outside bearing race where it had been getting hot.
Be careful not to roll that small O-ring when inserting the axle into the housing. Pretty easy to do.
Now, back to my 472 build, rest time is over.
Good Luck, Larry
O ring in the housing?
Hello Impalaman,
Before you cut the races off the bearings, were you able to tell if the bearings were producing the noise in your youtube clip? If not, when you replace the bearings and install the axles you should try spinning the axles as you did in the youtube clip. With new bearings, it may be more difficult to spin the axles. I would consider this a good sign. If the noise is still present, it is possible the noise is coming from the differential side gears as they rotate the carrier pinion (spider) gears. This may or may not be a good sign. How many miles are on the odometer? Do you know the history of the car?
Christopher Winter
Quote from: cadman56 on February 13, 2016, 04:05:48 PM
Be careful not to roll that small O-ring when inserting the axle into the housing. Pretty easy to do.
Now, back to my 472 build, rest time is over.
Good Luck, Larry
Good tip. I assume you are referring to the O Ring in the oil seal.
Quote from: savemy67 on February 13, 2016, 09:53:49 PM
Hello Impalaman,
Before you cut the races off the bearings, were you able to tell if the bearings were producing the noise in your youtube clip? If not, when you replace the bearings and install the axles you should try spinning the axles as you did in the youtube clip. With new bearings, it may be more difficult to spin the axles. I would consider this a good sign. If the noise is still present, it is possible the noise is coming from the differential side gears as they rotate the carrier pinion (spider) gears. This may or may not be a good sign. How many miles are on the odometer? Do you know the history of the car?
Christopher Winter
This is a survivor car with 94,500 miles. It was driven by a long-lived gentleman who worked at a Cadillac dealership in Ohio. It spent time in storage and then was sold by the son to the previous owner about a year and a 1/2 ago. I bought it just recently. The story was that the car was well maintained. It appears as though it was but I do not know how long it was in storage. As you know, idle time does damage in some cases.
I will try to spin it up when I get the new outer bearings installed and see what happens.
Most of these types of bearings have a round groove for an O-ring in the outside face of the outer race & this groove is closest to the axle flange. It is obvious in your pictures. They keep dirt from getting into the axle housing & keep differential oil from getting out. It is easy to roll or cut those O-rings. My 56 had O-rings and so did a 60 I did a couple of years ago.
These bearings are sealed at the factory. I sold bearings and it amazed me how many people removed the side seals from these bearings. Larry
The grease is to keep the bearings alive until the oil works its way from the diff to the bearings. As for the oil seal, there shouldn't be a groove where the lip rides on the axle. If there is, you can either replace the axle, have it filled and machined or use an axle repair bearing (this method I've used numerous times and works well) http://www.timken.com/en-us/products/bearings/productlist/roller/cylindrical/Pages/ACAxleRepairBearings.aspx
Bill
Quote from: bill06447 on February 14, 2016, 07:13:17 PM
The grease is to keep the bearings alive until the oil works its way from the diff to the bearings. As for the oil seal, there shouldn't be a groove where the lip rides on the axle. If there is, you can either replace the axle, have it filled and machined or use an axle repair bearing (this method I've used numerous times and works well) http://www.timken.com/en-us/products/bearings/productlist/roller/cylindrical/Pages/ACAxleRepairBearings.aspx
Bill
The axle housing and the shaft look good. Also this OEM bearing had no grooves in it to accommodate O rings. Once the bearing is fully seated, the oil seal butts up against it. I've attached the bearing and retainer called for on this car. Timken SET10.
On the lighter side, I found bearings and seals for $67 bucks on rockauto.com!! Nice !
That picture would be a Generic Picture of an axle bearing and retainer.
The new one could have the "O" Ring in place.
As for the lubrication of the bearing, definitely don't pull off the side covers, as a properly manufactured bearing will last for many years with the factory-installed grease.
Bruce. >:D
Parts should be in today! Soon I'll get this beast back on the road.
NO CHANGE!
New rear axle bearings did nothing. Sound is still there. Accompanies a vibration once the car gets around 55 mph. If you go up a hill, at around 65 mph for example, and accelerate the noise and vibration get worse. The vibration will rattle the little metal door on the passenger's cigar lighter.
I started looking that the section of vibration diagnosis in the front of the shop manual. Will start going through those steps tomorrow. From indications it sounds as though it may be a torque sensitive issue.
Mr Chevrolet,
From what you have said in previous posts I would be looking at the driveshaft's constant velocity joint. If worn or if incorrectly installed it will product the symptoms you describe.
Greg Surfas
Agree with Greg.
Also, you may want to check the rear trans mount as sometimes those go causing a vibration. If that is questionable, the engine mounts in front should be inspected too. One of my friends has this problem on his 1975 Cadillac Fleetwood and it has been diagnosed as drive shaft, he is looking for one (the Fleetwood is a little longer than DeVille). The trans/driveshaft/diff are all similar from 1970 thru 76 (2.93, 3.15 (1970-74), and 2.76 (1975 & 76)).
I think looking at the shop manual under vibration section is a good place to continue the process.
I have had to replace the rear axel bearings in my two 1970 Cadillacs once they reach about 100k miles. The noise was just ever so slightly noticeable at the time of rebuild. Now you are probably set for life on rear axel bearings for this car, one less thing to worry about.
Quote from: Scot Minesinger on February 20, 2016, 08:30:04 AM
Agree with Greg.
Also, you may want to check the rear trans mount as sometimes those go causing a vibration. If that is questionable, the engine mounts in front should be inspected too. One of my friends has this problem on his 1975 Cadillac Fleetwood and it has been diagnosed as drive shaft, he is looking for one (the Fleetwood is a little longer than DeVille). The trans/driveshaft/diff are all similar from 1970 thru 76 (2.93, 3.15 (1970-74), and 2.76 (1975 & 76)).
I replaced the trans mount recently. Also the engine mounts were replaced by the previous owner and appear new. I checked the bolts on them and they are tight.
One thing I did not mention was that two of the bolts on the drive shaft flange which connects to the diff are replacements. Apparently two of the bolts were stripped out at one point. Some one bored out the holes a little and used slightly larger bolts with lock washers and nuts. It appears to be grade 8 stuff and both bolts appear to be the same length. I have no idea whether or not it is balanced.
I will post some pics of the drive shaft.
Drive Shaft - All the wet oil is from me using WD40. Not car leaks.
Drive Shaft
Drive Shaft
Took another test drive this morning. Varied the throttle in both 2nd and 3rd gear.
In 3rd gear above 50, if you accelerate (without down shifting.... lugging the motor a bit) the problem is very pronounced. Noise and vibration.
If you leave the car in 2nd gear and speed up past 50, the problem is hardly noticeable if at all.
It rears its head when you lug the engine.
I would think that the two good original bolts would align shaft so it is centered. Plus if it was out of center the faster spinning (non-engine lug) would show itself in vibration fairly independent of anything except drive shaft rotation speed. This happened to me once on a truck where engine lugging produced vibration, and it turned out to be the automatic transmission (2007 GM full size truck w/V-8).
I am still going to suggest you stick a camera undwr there to see what is actually moving.
Can't hurt.
Jeff
Quote from: impalaman on February 20, 2016, 01:10:31 PM
Drive Shaft - All the wet oil is from me using WD40. Not car leaks.
Is that casting part at the differential cracked or is that an optical illusion? (the second picture from the drive shaft)
Quote from: Roger Zimmermann on February 21, 2016, 05:04:26 AM
Is that casting part at the differential cracked or is that an optical illusion? (the second picture from the drive shaft)
A shadow caused by the flash being slightly off centre to the camera lens/CCD.
Bruce. >:D
Bruce, I'm not sure that we are "speaking" about the same thing. Have a look at the red arrow in the picture...
That looks like a shadow from the rib in the casting.
Could be. Only impalaman can verify!
Never experienced a problem like this (fortunately), but wouldn't any looseness be more prevalent when the throttle is released? I would think under load any looseness/slack would be taken up by the load. In other words, I would have expected the noise/vibration to appear releasing the accelerator; not under load. Just my thoughts.
Impalaman - is there a clunking when you release the accelerator and then give it gas lightly in high gear?
Quote from: Jon S on February 21, 2016, 10:22:53 AM
Never experienced a problem like this (fortunately), but wouldn't any looseness be more prevalent when the throttle is released? I would think under load any looseness/slack would be taken up by the load. In other words, I would have expected the noise/vibration to appear releasing the accelerator; not under load. Just my thoughts.
Impalaman - is there a clunking when you release the accelerator and then give it gas lightly in high gear?
No. The drive train is tight.
That is a shadow in that photo but it startled me upon first examination. :)
The only auto transmission problems I've ever experienced in any car came in the form of slippage. I've never heard an auto trans make a noise like this but I'm started to suspect. Saw this post over
on another forum:
"Took my tranny to get rebuilt. It was planetary gears. They looked all chewed up. Turns out that is the reason I had a very slight vibration in 3rd gear under very hard acceleration for many years. Thanks for the help guys."http://www.thirdgen.org/forums/transmissions-drivetrain/191228-grinding-noise-torque-converter.html
Hello Impalaman,
There are two clues/symptoms mentioned in your prevoious posts that you may want to investigate more closely. Based on no change subsequent to replacement of the rear wheel bearings, the first clue is the replacement bolts in the differential pinion flange. Speculating on why the bolts were replaced leads one to think that there was a problem with the differential, the driveshaft and double Cardan joints, or the transmission. If the car was maintained by a Cadillac dealership, what circumstance would cause a dealership to replace two of the four bolts? You may need to consider the possibility that at some point there was a significant problem with one of the driveline components. Since the driveshaft is relatively easy to get to, check it first. From under the car, give the driveshaft a good back and forth yank near each end of the driveshaft - radially (side to side), not axially (front to back). Rotate the driveshaft 90 degrees and repeat. Do this two more times to check for any looseness in the double Cardan joints. This may expose looseness in the differential and or transmission as well. To be absolutely sure the driveshaft is perfect, you could take it to a shop that could check it for balance (include the four pinion flange bolts).
The second clue is that the problem rears its head when the engine lugs. When the speed of the transmission output shaft multiplied through the differential fails to provide enough twisting leverage (torque) required to move the car at that moment, the engine will lug. One of your posts mentioned lugging in third gear. At a lower road speed, can you get the engine to lug in second? If not, that would lead me to consider the transmission may have a problem. You could do a pressure check on the transmission before pulling it out of the car. The shop manual should have the specs for pressure testing the transmission.
Diagnosing problems like this can be time consuming. Using the shop manual vibration diagnosis checklist should help. By no means am I an expert at these things, but using a methodical approach will minimize the money spent to resolve the problem. If the worst case scenario is having to rebuild the transmission, would that be a bad thing for a 45 year old car that has sat for a while? It could put a dent in your wallet, but that pain will subside the more you drive your '71.
Respectfully submitted,
Christopher Winter
A damaged flex plate may cause similar symptoms. It could be warped, or cracked, wouldn't hurt to pull the inspection cover and give it a good look with a bright light.
Thanks for the tips guys. I will check those items out as soon as I can. I also plan to go to the transmission shop and have a pro ride along with me and listen to this thing.
Well I've found something. Looks like the upper ball joint on the pass side is coming out. Appears to have
been replaced at some point (badly).
Any recommendations on a brand for ball join replacement?
This may be the source of the vibration.
This definitely doesn't look right.
I would try to get a Made in USA Moog.
BTW, I doubt that is the cause of your vibration under load, but needs to be replaced.
Mr. Chevrolet,
ANYTHING, REPEAT ANYTHING loose in the suspension or drive line will cause a vibration under certain specific conditions. The reason new cars are so smooth is because every component is new and tight. The way I see it you have been chasing this vibration for a while and either want to cure it or live with it. If you want to cure it you need to go through the suspension, drive line, motor mounts and body mounts to determine which need replacement. In your shot of the ball joint I noticed what appears to be rust at the inner end of the upper control arms where the control arm bushings are. These are also part of the suspension and could be a direct source of the vibration. NVH (noise, vibration harshness) is an engineering task performed during design and production testing of vehicles at which time every component is tested to see how it reacts when exposed to ALL the expected conditions the vehicle is expected to encounter. There is not a single component that is not exposed to potential vibratory transmission, so they all are important.
My current "toy" is a '79 Paris, and without much fanfare I proceeded to replace all the suspension, steering and driveline components. My intent is to have it drive and ride like new, and it does.
Greg Surfas
Quote from: "Cadillac Kid" Greg Surfas 15364 on February 27, 2016, 01:48:14 PM
Mr. Chevrolet,
ANYTHING, REPEAT ANYTHING loose in the suspension or drive line will cause a vibration under certain specific conditions. The reason new cars are so smooth is because every component is new and tight. The way I see it you have been chasing this vibration for a while and either want to cure it or live with it. If you want to cure it you need to go through the suspension, drive line, motor mounts and body mounts to determine which need replacement. In your shot of the ball joint I noticed what appears to be rust at the inner end of the upper control arms where the control arm bushings are. These are also part of the suspension and could be a direct source of the vibration. NVH (noise, vibration harshness) is an engineering task performed during design and production testing of vehicles at which time every component is tested to see how it reacts when exposed to ALL the expected conditions the vehicle is expected to encounter. There is not a single component that is not exposed to potential vibratory transmission, so they all are important.
My current "toy" is a '79 Paris, and without much fanfare I proceeded to replace all the suspension, steering and driveline components. My intent is to have it drive and ride like new, and it does.
Greg Surfas
Yes after looking over the front end, I am very tempted to replace all of the bushings. However, this car drives great. The steering is tight. It doesn't wander around. I drive old cars and I drive an E class as a daily driver and this old Deville really does drive well...... except for the vibration of course.
Like Greg, I replaced every front and rear suspension component in all three of my 1970 Cadillacs because I wanted them to drive as new.
The weak link on these 1965-76 Cadillacs is the upper control arm bushings, investigate thoroughly, as those seem to fail major on even low mileage cars. Here is a picture of my 1970 Cadillac upper control arm bushing with 35k miles last year. Completely gone. Car did not vibrate, but did not ride or steer well at high speed.
One thing to remember before tightening up any bushings is to put the car down off the jackstands, and let the car settle to its correct stance, and then tighten up the bushing nuts/bolts. In the case of the front suspension, roll the car backwards and forwards to allow the sideways pressure to be relieved.
Tightening the bushings up whilst the suspension is in complete "drop" mode, will prematurely strain the bushings when the car is being driven.
Bruce. >:D
Quote from: The Tassie Devil(le) on February 27, 2016, 07:40:55 PM
One thing to remember before tightening up any bushings is to put the car down off the jackstands, and let the car settle to its correct stance, and then tighten up the bushing nuts/bolts. In the case of the front suspension, roll the car backwards and forwards to allow the sideways pressure to be relieved.
Tightening the bushings up whilst the suspension is in complete "drop" mode, will prematurely strain the bushings when the car is being driven.
Bruce. >:D
Excellent tip Bruce. I rebuilt (restored basically including sand blasting) the front end of my 66 Impala (hence the name... it sort of stuck) years ago. I didn't really want to go there at this time but oh well.
Tonight I disconnected the upper ball joint on the pass side but am unable to pull off the camber adjuster. I may have to pull off the control arm anyway. If that is the case the bushings will be replaced while it is off.
The bushings look good though surprisingly from what I can tell.
Any tips on removing the eccentric camber adjuster? (Yes I marked it and the arm)
I thought maybe I could cut the ball joint stud above the camber adjuster with my sawzall.
LOL... man that would an epic mess.
Hello Impalaman,
Prior to knowing about the ball joint, many here focused on driveline issues based on the symptoms you described. Subsequent to seeing the pictures of the ball joint, a review of your very first post may cause some here to recommend correction of the ball joint issue, and a re-evaluation of your symptoms.
Your first post mentioned a noise heard from the front of the car under uphill acceleration, and no noise heard when the car was on a lift. Under uphill acceleration, the weight over the front wheels is reduced slightly. With the ball joint improperly installed, the suspension geometry is not correct. Under certain road/load conditions, you may get an unwanted vibration at the front of the car. There is also a potential hazard with the ball joint improperly installed (I am assuming the ball joint is improperly installed based on the photo). If the ball joint is not fully seated in the control arm, the ball joint stud, camber eccentric, and steering knuckle are not fitted together as designed, and stress on the castellated nut holding everything together may be increased.
Your most recent post indicates that you have started working on correcting the ball joint issue. I would encourage you to repair the ball joint, and if the bushings need to be replaced, replace them. When all the parts are back together, take the car for a spin, and let us know if there is a change. At the least, discussion forum members can eliminate the front end as a possible contributor to your vibration issue. Good luck and work safely.
Respectfully submitted,
Christopher Winter
Dont forget about the play in the steering of the older cars. Shut the car off and wiggle the wheel. Your front end can be vibrating and you may not even know it. If it was on a new Honda it would be much more noticable.
Jeff
Hello gents. I replaced the ball joint. Looks good. Drives great. Noise and vibration is still there. Headed to the transmission shop next week.
This probably has happened to all of us at one time or another, where you suffer a symptom and search for the cause repairing many things that were marginal to no avail. Then when you finally find the real problem it is repaired - then wow do you have a smooth wonderful driving car.
Happened to me on 1 1985 Caprice with 200k miles (305V-8). Car slugged only after a long warm up under a slight load. Replaced all the possible engine tune up and maintenance items including all vacuum hoses all to no avail. Then after numerous mechanics could not figure it out bought shop manual and it narrowed it down to egr valve of rods, replace egr valve - and it was cured. Then the engine was so smooth and quiet my Dad even accidentally tried to start it when it was running.
Do not give up.
One time I did give up on a 72 Eldorado a/c restore, just could not get it working after every component had been replaced, some twice (new part are often bad). Then the car came back to me for another reason and I tried again, turned out to be an evaporator, a new replacement that was bad. Here is a picture of the bad evap. after I got it out of the 72 Eldorado that caused me so much trouble. You know if I returned it this, would end up in someones car today, so did the Cadillac club a favor.
Quote from: impalaman on March 04, 2016, 03:07:03 PM
I replaced the ball joint. Looks good. Drives great. Noise and vibration is still there. Headed to the transmission shop next week.
When you show us the bad ball joint, I was tempted to write that it cannot cause a vibration. However, by reading at other comments, I had doubts; now, after you replaced it, I do regret that I stayed silent. Anyway, the way the bal joint was looking was not fantastic
Quote from: Jon S on February 27, 2016, 12:10:14 PM
BTW, I doubt that is the cause of your vibration under load, but needs to be replaced.
I still believe you have a motor mount or transmission mount problem despite the fact they are new. One could be separating under load causing that vibration and then re-seating when you decelerate.
If the engine and trans mounts are original, they should be replaced anyway - if you can replace a ball joint, this is an easy task for you. I'm working on a 1975 SDV timing chain/rear main seal replacement. Since the fuel pump and oil pump have to be removed and it is much easier to remove oil pan by hoisting engine up an inch or so, it is crazy for me not to replace the front mounts. Engine mounts are replaced. Glad I did because bolts were near frozen to block, nuts were difficult to remove, and would have been much more difficult with less access.
My '62 does exactly the same thing, but at a higher speed than that. We pulled the driveshaft, rebalanced, etc. and it got a lot better (but not perfect).
The "waaw waaw waaw" description is exactly right.
Gary
Gary,
Was the sound/vibration there all the time at the same speeds? I occasionally get the waw waw waw but not all the time. O just back off a bit and it goes away.
Jeff
Quote from: Gary Christensen CLC # 21112 on March 14, 2016, 05:18:26 PM
My '62 does exactly the same thing, but at a higher speed than that. We pulled the driveshaft, rebalanced, etc. and it got a lot better (but not perfect).
The "waaw waaw waaw" description is exactly right.
Gary
Very interesting Gary. What all does this entail? Did you simply remove it and take to a shop? What about the pinion flange on the diff? Did it need any attention?
Thanks
I don't know why the thought eluded me. I just got my 75 out of the (driveshaft) shop for the exact same symptom; vibration under power. Our shafts have a CV joint on each end with 2 universal joints each. The CV joints take a special tool to lubricate them which usually results in them never getting lubed and the grease washes out, leaving the CV joint dry and soon worn to the point of failure, preceded by a short period of vibration as you are experiencing.
You can either pull the shaft and take it to a reputable shop, or you can take the car and the shop will do the R&R.
Mine just had bot CV's and the universals replaced and the shaft was balanced. Result: good as new. I don't know where you are, but there are usually a couple of good driveshaft companies in most major cities, since trucks eat them for breakfast.
Greg Surfas
Look up "driveline" (google it), it is a National Chain and it is one of the few mechanical service providers in our area that I trust. Of course it is all about the people employed locally. Anyway I have used them to balance about 6 drive shafts, all very nice work. When I reseal a transmission and tail has to come off, I routinely get the drive shaft serviced and balanced. It only costs $90 and they knock it out in 3 hours or so. They even paint it for you.
Quote from: Scot Minesinger on March 22, 2016, 12:04:13 AM
Look up "driveline" (google it), it is a National Chain and it is one of the few mechanical service providers in our area that I trust. Of course it is all about the people employed locally. Anyway I have used them to balance about 6 drive shafts, all very nice work. When I reseal a transmission and tail has to come off, I routinely get the drive shaft serviced and balanced. It only costs $90 and they knock it out in 3 hours or so. They even paint it for you.
We have a service shop here in central AL that specializes in driveshafts. It appears I have a new mission. I will hopefully remove it in the next few days and take it in for balancing.
I would suspect that it will take more than balancing. IF it is the shaft wear of the CV and Universal joint is very common and (again) if the shaft is causing the vibration a complete rebuild AND re balancing is usually the cure.
Greg Surfas
Just dropped it off at the driveshaft shop. Let's see what they say.
Driveshafts, springs, and trailers. That's what the sign says.
https://www.facebook.com/pages/Birmingham-Spring-Service/168200233190295?fref=ts
IF the drive shaft has ever been bent and then straightened its possible (or likely I think) that it will eventually return to the bent state. I had one once that the shop said was bent but they were able to straighten it and balance and the whole works. Before long had a vibration again but didn't suspect the shaft cuz I just had it done. After trying everything else I took it to a different shop and they said it was bent and they didn't believe in straightening them and recommended replacing it which I did and it was good after that.
TJ,
How on earth would you be able to bend and then (more amazing) straighten the drive shaft on a 1971 Cadillac?
Greg Surfas
I actually can't remember if that was on a Cadillac or Pontiac, had em both at the same time and had done a lot of work to both. Thinking about it now could also have been a Buick. What ever it was had a trailer hitch. All 3 of those were in my 'first' wave of cars. Each was going to be my ultimate car that I was going to fully restore / customize and keep forever, at least that was my plan when I was 18.
Not sure how it got bent, was apparently like that when I got the car. It was not so bent that you could see it laying under the car with the wheels jacked up. They showed it to me in a lathe like thing and with fixed reference points you could see it was bent. How they straightened it I didn't see. How it went back to bent I was told that once metal like that bends it tends to want to stay bent so even if it gets straightened it wants to go back to bent so it does not take as much force to re bend it as it took to bend it in the first place. The shop that repaired it the second time by welding my ends onto a new tube said they see that a lot on trucks. Don't know if its stress from towing or maybe stuff hitting em 'off roading'? I remember putting a new tube on my parts was cheaper and faster than getting a completely new shaft which makes me think maybe it was the Cadillac since that likely would have been a pretty expensive shaft vs something that was on a Pontiac or Buick. I think it cost me a whole paycheck at the time and I had to wait till payday to pick it up. Had to ride by bicycle to work that week.
Basically my point is that if a shop says your shaft is bent I would not bother trying to straighten it unless they are willing to give you a darn good warranty labor included.
I too have seen bent tailshafts. Maybe caused by going over an object, striking it. The worst one was caused by a Fork-lift, moving the car. As the rear end dropped whilst the car was being lifted, the shaft hit the Fork-lift fork.
Bruce. >:D
Hello TJ,
I think the first shop saw an eighteen year old, and took advantage of you. It happened to me - once - in Minnesota!
If the driveshaft - which is a steel tube - was in fact bent, it means that the metal at the point of the bend had surpassed its yield point. Steel is a very elastic material, but once its yield point is exceeded, it will not return to its original shape by itself. I would seriously doubt that the first shop "unbent" the driveshaft, and sometime later the driveshaft bent itself again. Perhaps this is why the second shop recommended replacing the tube.
Respectfully submitted,
Christopher WInter
Quote from: savemy67 on March 25, 2016, 08:41:39 PMI think the first shop saw an eighteen year old, and took advantage of you
That was certainly a possibility. I can't remember the car for sure but I sure remember paying for that 'repair'. I even remember having to bribe a friend to drive me to the shop in his TransAm to pick up the shaft. Shaft would not fit anywhere inside that car so I sat one end between my feet on the floor and held it straight up. Good thing it was a nice day and a T top car.
With the noise coming from the front under load, I vote for a bad motor mount as suggested. Maybe the noise is the engine fan hitting the fan shroud.
As you might have guessed, the driveshaft is fine. The shop did not find anything wrong with it. Figures.
Well I keep eliminating the cheap fixes one by one.
The shop charged $32 for the balance check.
Transmission shop is next.
Have you tried old engine motor mount test?
With the hood open, place selector in Drive and rev the engine to about 1,000RPM with your foot on the brake. See if the air cleaner moves. Then do the same thing placing the selector in Reverse. Again, look for air cleaner movement, this time in the opposite direction. You should detect an ever so slight movement in either direction.
If it is more significant either the left or right motor mount is defective and may be causing that vibration as I initially thought.
Quote from: Jon S on March 27, 2016, 03:06:31 PM
Have you tried old engine motor mount test?
With the hood open, place selector in Drive and rev the engine to about 1,000RPM with your foot on the brake. See if the air cleaner moves. Then do the same thing placing the selector in Reverse. Again, look for air cleaner movement, this time in the opposite direction. You should detect an ever so slight movement in either direction.
If it is more significant either the left or right motor mount is defective and may be causing that vibration as I initially thought.
Since they are both fairly new, I have not but I will try whatever is the cheapest! Off to the garage now!
I performed this test and saw only very small and expected, in my opinion, movement in both directions under load as described above. I would guess 1/4 inch movement in both directions. A small amount for sure.
I did tighten the driver side mount. It was not loose but it was not quite tightened down as much as I thought it needed to be. The pass side seemed fine. Both are in good condition with no cracks.
Quote from: impalaman on March 27, 2016, 05:58:09 PM
I performed this test and saw only very small and expected, in my opinion, movement in both directions under load as described above. I would guess 1/4 inch movement in both directions. A small amount for sure.
I did tighten the driver side mount. It was not loose but it was not quite tightened down as much as I thought it needed to be. The pass side seemed fine. Both are in good condition with no cracks.
A simple test to determine condition of motor mounts. Yes, 1/4" movement in both directions is perfect. One less variable . . .
Well the car is at the transmission shop. The trans shop recommended having a different drive line shop take a look at the drive shaft. (Recall I had it looked at once but they found nothing) After following the trans shop's recommendation the drive shaft was a little out of balance. They also installed new joints front and back.
The trans shop said that there was excessive play in the transmissions output shaft. It moves side to side in other words. I knew it had some play but did not know that it was a problem.
Regardless the transmission will be rebuilt while it is out of the car. Hopefully all of this will cure the vibration issue.
Lastly I installed a new set of Hankook Optimo 70,000 mile whitewalls. I couldn't stand those Mastercrafts that were on the car.
If there was that much wear in the transmission output shaft, wear in the bushing, I would have recommend a new front yoke too. Too late now since you have the shaft joints replaced.
Good luck, Larry
What would cause that output wear? Bad CV/U joints that got ignored by a previous operator?
Quote from: TJ Hopland on April 13, 2016, 08:28:36 AM
What would cause that output wear? Bad CV/U joints that got ignored by a previous operator?
No clue.
Quote from: cadman56 on April 12, 2016, 10:02:13 PM
If there was that much wear in the transmission output shaft, wear in the bushing, I would have recommend a new front yoke too. Too late now since you have the shaft joints replaced.
Good luck, Larry
If I had to replace the yoke, where could I get one?
Hello impalaman,
Worn universal joints (or constant velocity Cardan Joints) could result in excessive bushing wear and excessive radial play in the output shaft. However, since, generally, bushings are softer than driveshaft yokes and output shafts, it is more likely that any wear is confined to the bushings. Since the transmission shop notified you of the excessive radial play at the output shaft, the transmission shop should be replacing several bushings, or they should be giving you the clearance measurements for the shafts/bushings affected by a driveshaft with worn u-joints, with the shop's assurances that the remaining bushings and clearances are OK.
The front of output shaft, at the flange, has a bushing that rides on the hub of the rear internal gear. The output shaft is also supported by the case bushing, just in front of the governor and speedometer gears. The driveshaft yoke slips over the splined end of the output shaft and the yoke is supported by one or two bushings in the tailshaft housing. Clearances for the bushings should be on the order of .002 to .008 of an inch. Bushings are not meant to support a great deal of weight or force - that is a job for bearings. Bushings function as guides to control location and rotational movement.
If your transmission shop wants to charge extra to remove/replace bushings, I would anticipate maybe an extra $100 for the parts and labor. Given that the shop noticed the excessive play, you should probably authorize this repair.
Respectfully submitted,
Christopher WInter
Hello Impalaman,
I wrote about replacing the yoke from experience on (2) cars, a 1964 Ford Galaxy 500 & a 1991 Brougham dElegance. Replacing the transmission output shaft bushing & drive shaft yoke eliminated the drumming vibration in both cases. I only reply from experience. A drive shaft shop should be able to locate & replace the yoke with no problems. Have your yoke measured with a micrometer against a new one on the outside & check for wear ridges in the splines on the inside. And check the splines on the output shaft of the transmission. There is also a raised section in the center of the yoke that a spring loaded piece works on. That should have been checked for wear ridges by the drive shaft shop too.
Good luck, Larry
Update:
Transmission and driveshaft rebuilt. (The bushings in the tail shaft in the trans were shot.)
Passenger side engine mount replaced.
I replaced the drivers side mount and the trans mount a few weeks ago.
None of this has corrected the vibration.
I will bring the car home for a while and then maybe we will look at rebuilding the diff. Neither I nor the trans shop owner can hear and/or detect any
noise coming from the diff. After his test drives he "thinks" there might be an issue with the pinion shaft in the diff. We would need to tear it down
to see.
In the mean time I am going to install the smog pump removal kit from 500cid.com. Part number BL48.
That will at least make me feel a little better.
You will like the results of the smog removal kit, I did that on a 1972 Cadillac. I found a 1970 alternator mounting bracket set too and was able to really clean it up.
Hope the differential rebuild clears it up. Glad you got the trans fixed that needed it anyway.
When you do find the real problem, this will be one smooth nice Cadillac. As I have probably written before, hunting down a problem like this has you fixing many things along the way that were just partially not 100%, and so when you get there with the right repair - wow is it nice.
Hang inn there and never give up.
Quote from: Scot Minesinger on April 27, 2016, 07:54:13 AM
You will like the results of the smog removal kit, I did that on a 1972 Cadillac. I found a 1970 alternator mounting bracket set too and was able to really clean it up.
Hope the differential rebuild clears it up. Glad you got the trans fixed that needed it anyway.
When you do find the real problem, this will be one smooth nice Cadillac. As I have probably written before, hunting down a problem like this has you fixing many things along the way that were just partially not 100%, and so when you get there with the right repair - wow is it nice.
Hang inn there and never give up.
Hanging with it like a rusty fish hook!
Quote from: Scot Minesinger on April 27, 2016, 07:54:13 AM
You will like the results of the smog removal kit, I did that on a 1972 Cadillac. I found a 1970 alternator mounting bracket set too and was able to really clean it up.
Hope the differential rebuild clears it up. Glad you got the trans fixed that needed it anyway.
When you do find the real problem, this will be one smooth nice Cadillac. As I have probably written before, hunting down a problem like this has you fixing many things along the way that were just partially not 100%, and so when you get there with the right repair - wow is it nice.
Hang inn there and never give up.
Instructions say to remove crank pullies and balancer. Not sure why the balancer needs to come off. Took the crank pulley bolts out. Is the pulley suppose to slide off at this point? The factory service manual is confusing on this.
I took the cork out of the end of the crank.
A complete set of rear trailing arm bushings is on order. I plan to replace them this up coming weekend.
If this has no effect I will add a shim using 1/4 inch plate steel under the transmission mount.
The results of these two steps will determine whether I dive into the differential or not.
The quest continues.
This past weekend I added some 1.5 inch lift twist-in spring helpers in the rear coils. While the car was in the air I inserted them by hand. No tools
were required. With the car on the ground they offer only minimal additional lift and I was unable to determine whether or not the
geometry change they offered affected the problem.
Quote from: impalaman on May 23, 2016, 03:44:37 PM
A complete set of rear trailing arm bushings is on order. I plan to replace them this up coming weekend.
If this has no effect I will add a shim using 1/4 inch plate steel under the transmission mount.
The results of these two steps will determine whether I dive into the differential or not.
The quest continues.
This past weekend I added some 1.5 inch lift twist-in spring helpers in the rear coils. While the car was in the air I inserted them by hand. No tools
were required. With the car on the ground they offer only minimal additional lift and I was unable to determine whether or not the
geometry change they offered affected the problem.
They may fall out with normal driving. Have you considered air shocks?
Quote from: Jon S on May 23, 2016, 03:46:49 PM
They may fall out with normal driving. Have you considered air shocks?
I took a long test drive. They stayed put. I will probably remove them soon anyway. The car rides well and the shocks seem to be fine.
I will replace them also. Might as well. No telling how long they've been in there.
If you are replacing the rear suspension bushings, which is a great idea - have done mine too, now is the time to replace the springs and shocks too. I use a set of spring compressors to replace rear springs, as the factory shop manual describes a crazy difficult method. Also you need to sacrifice a small 1/2" wrench by bending it to make the tool needed to replace rear shocks. The shocks and springs are not expensive (les than the cost of the 8 bushings for me anyway).
Quote from: Scot Minesinger on May 24, 2016, 07:24:21 AM
If you are replacing the rear suspension bushings, which is a great idea - have done mine too, now is the time to replace the springs and shocks too. I use a set of spring compressors to replace rear springs, as the factory shop manual describes a crazy difficult method. Also you need to sacrifice a small 1/2" wrench by bending it to make the tool needed to replace rear shocks. The shocks and springs are not expensive (les than the cost of the 8 bushings for me anyway).
Good tip on the shock tool. Thanks! I was thinking about using a long wrench to go in from the side over the frame rail but had not looked at it extensively as of yet. Bending a Harbor Freight wrench is not a problem!
My bushings came in yesterday. I ordered them from http://www.stylintrucks.com/. Go figure.
Tried rockauto.com but they were out of stock. A couple of other places wanted too much money. CaddDaddy.com wanted $150 per set. I received all eight for $106 from the truck website.
Update: Replaced rear springs, rear trailing arm bushings and shocks all the way around.
The shocks were shot. :)
All this had no effect what so ever on the vibration and noise at highway speeds. >:(
On the lighter side, the car rides wonderfully! Dead smooth like a Cadillac should. (As long as you stay below 50 mph)
Only thing left is to tear the rear diff apart and take a look at the pinion bearings.
Mr Chevrolet,
I sure seems like you either got the first car off the assembly line after someone had a wild week end, or you have a built in gremlin. You have been chasing ghosts for a couple of months seemingly without much success at anything other than spending money for repairs that don't seem to correct the problem.
What I am going to suggest might seem sacrilegious to some on this forum, but it seems the information you have received although worth the price you paid for it did not get you the results you want.
I would suggest you start at your local Cadillac dealer, and if they cannot help you try another "high end" dealership. Ask them to diagnose your issues (for pay).
Greg Surfas
Quote from: "Cadillac Kid" Greg Surfas 15364 on June 01, 2016, 01:42:48 PM
Mr Chevrolet,
I sure seems like you either got the first car off the assembly line after someone had a wild week end, or you have a built in gremlin. You have been chasing ghosts for a couple of months seemingly without much success at anything other than spending money for repairs that don't seem to correct the problem.
What I am going to suggest might seem sacrilegious to some on this forum, but it seems the information you have received although worth the price you paid for it did not get you the results you want.
I would suggest you start at your local Cadillac dealer, and if they cannot help you try another "high end" dealership. Ask them to diagnose your issues (for pay).
Greg Surfas
Not a bad idea at this point. However the diff is the only thing in the drive train which has not been touched..... other than just changing the fluid.
Quote from: "Cadillac Kid" Greg Surfas 15364 on June 01, 2016, 01:42:48 PM
Mr Chevrolet,
I sure seems like you either got the first car off the assembly line after someone had a wild week end, or you have a built in gremlin. You have been chasing ghosts for a couple of months seemingly without much success at anything other than spending money for repairs that don't seem to correct the problem.
What I am going to suggest might seem sacrilegious to some on this forum, but it seems the information you have received although worth the price you paid for it did not get you the results you want.
I would suggest you start at your local Cadillac dealer, and if they cannot help you try another "high end" dealership. Ask them to diagnose your issues (for pay).
Greg Surfas
I seriously doubt any Cadillac dealership has mechanics familiar with a 1971 Cadillac. I think Impalaman has approached the problem properly and is down to the last variable.
Hello. I went trough the same procedure as you with my -58 a few years ago. It turned out to be the water pump hub not being exactly centred on the shaft. Try simply removing the fan and se if it makes a difference.
Yes, I'm thinking the Cadillac dealership will do more harm than good. It understood that the idea is find an experienced mechanic who is capable of determining the problem and pay to find the problem. If someone of this caliber exists and is trusted, it might be a good idea.
There is a procedure in the shop manual to eliminate vibration, and it is presumed this has been followed and exhausted. The water pump issue would surface with car in park and racing engine with belt on and off (following procedures so it does not overheat). I fixed a 1975 Caddy that suffered a similar problem following shop manual without leaving the garage to diagnose and repair.
Bushings not properly pressed into the four rear control arms will cause a vibration, presuming that was done correctly and it is not the problem. The only thing remaining is the rear differential - just about.
One of my friends suffers a vibration at high speed and it has been diagnosed to be the drive shaft universal joint gone bad.
Keep us posted.
Vibrations are vibrations and believe it or not new cars just off the assembly line sometimes have them./ One of the most important positions in the "get ready" line of a new car dealership is the person or people that take these cars for a final test drive to find anything that is amiss. Usually thes are the most experienced, older mechanics that have been doing this for decades. There is nothing mysterious about a noise or vibration if you know what you are doing and have done it your entire career.
Just my thought.
Greg Surfas
Please stay out of any Cadillac dealership. Two examples:
1: A local club member with a 69 deVille convertible went on a multi region tour to west Texas. He had problems so took it to a local Cadillac dealor. Cost him a fFORTUNE for tires, shocks & brakes & it took them almost three months to fix it. All parts are standard off the shelf GM parts.
2. I lost the speedometer, convertor lockup & cruise in SW Colorado in my 91 Brougham. The local Cadillac dealor told me to not even bring it in to them. Had to drive it all the through mountains to central KS with no speedometer & OD.
One question, does your car have the inner pipe inside the front exhaust pipes like some Chevys did in the 70's?
Good luck, you have been through the mill on this one.
Larry
Would that inner pipe cause a vibration? I would think that would be more of a rattle issue? I remember the original exhaust on my 73 had that double wall pipe in places.
Quote from: jenasp on June 09, 2016, 04:04:03 AM
Hello. I went trough the same procedure as you with my -58 a few years ago. It turned out to be the water pump hub not being exactly centred on the shaft. Try simply removing the fan and se if it makes a difference.
Thank you. I will try it! Since I live in a hot region I'll do it at night. No since running down the road when it's 95 without a fan.
Assuming I can remove the fan and still retain the pulley to drive the pump of course. I would have to check.
Quote from: TJ Hopland on June 14, 2016, 01:06:50 PM
Would that inner pipe cause a vibration? I would think that would be more of a rattle issue? I remember the original exhaust on my 73 had that double wall pipe in places.
That's a new one on me. Have no idea. The exhaust on this car is original believe it or not..... except for the muffler. I actually did some welding on the exhaust a while have thinking that might fix it.
That likely has a 'flex' fan. Easiest thing there would be to remove the fan then put the long bolts back in the spacer to hold the pulley in place. May need a couple washers to better hold the spacer and take up the space of the fan. If its a clutch fan then just a couple washers over the studs to take up some space and put the nuts back on.
Going down the road at 95* should be fine, you really don't need a fan while you are moving say over 30 mph, its when you stop there could be a problem. Think of your 'new' car, if you don't have the AC on most of the time you don't hear the fan run unless its really hot and you are stopped more than going.
Hello Impalaman,
your very first post indicated the 'vibration' was slowly oscillating like a Wah-Wah sound. I began to wonder if you were actually experiencing a sort of harmonic issue. That is why I mentioned the inner pipe.
Wish you lots of luck. Larry
'
Any luck finding the problem?
Did the vibration get fixed? If so, what was it?
I'm back. Had other priorities there for a while.
The next thing I am going to try is to have a new drive shaft built.
I want to get away from this double cardan joint stock drive shaft and have a conventional
one built.
I've been speaking with the trans shop and he feels like it is still a drive shaft vibration even though
we had the original one rebuilt a while back. He does not like the double cardan joints.
I can have a drive shaft built for a lot less money than a differential rebuild.
Any thoughts here? When did Cadillac stop using the double cardan drive shifts?
There are 100's of thousands of these out and operating correctly. They used the double carden joints to allow the lower driveshaft tunnel with the engine and pinion angles the cars was designed for. They quit using the double joints in 1977 when the crs were shorter, cheaper and intended to be interchangeable with the entire GM line.
Can you go to a one piece drive shaft? Yes, I did on my Hot rod 73 Coupe deVille because the stock joints would not take the torque and the angel changed when I installed a Moser 9" rear end. It was originally "certified" at 500 HP, but the Cadillac torque split the seamless tube and I had to go to a 3.5 inch 0.083 steel tube.
IO really would recommend finding someone who can actually check and repair your dirveshaft. Any shop that routinely works on large trucks should be capable, and the cost (I paid $400.00 for the last stock shaft rebuild (which includes balancing)) and the custom shaft cost me about 2.5 times that,
Greg Surfas
The drive shaft on my 1970 Cadillac is just shy of 130k miles and it works fine, had it to 75 mph last weekend on the highway. Smooth- like glass. There is nothing wrong with the idea of this drive shaft design. It is unlikely that the vibration is due to bad driveshaft design. You may need a rebuilt or rebalanced drive shaft, but not a new design. A custom new drive shaft will be very expensive.
One of my friends has a vibration like you wrote about on his 1975 Cadillac. The former mechanic diagnosed the problem as a bad drive shaft. I purchased one from Cadillac King and had it balanced. Will be installing soon and post results either way (by soon I mean within a month).
The stock drive shaft has already been rebuilt and balanced by a qualified shop which services the trucking industry. The vibration was unaffected.
Then perhaps look elsewhere for the vibration.
Greg Surfas
Quote from: "Cadillac Kid" Greg Surfas 15364 on September 13, 2016, 05:06:16 PM
There are 100's of thousands of these out and operating correctly. They used the double carden joints to allow the lower driveshaft tunnel with the engine and pinion angles the cars was designed for.
I agree with you. However at this point, I'm shotgunning this issue. It's either the drive shaft or the differential. I can have a new drive shaft made for about $350 here using heavy duty steel.
A diff rebuild at the shop will probably be much more. I'm going with what is cheaper first.
I expect to have the drive shaft made next week.
Let us know how that single piece drive shaft works out. We have heard from numerous folks (on this and other forums) that have tried to eliminate the double cardan joints and reports of noise, vibration and destroyed rear transmisswion and pinion bearings seem to be the norm.
Greg Surfas
Quote from: "Cadillac Kid" Greg Surfas 15364 on September 15, 2016, 02:05:00 PM
Let us know how that single piece drive shaft works out. We have heard from numerous folks (on this and other forums) that have tried to eliminate the double cardan joints and reports of noise, vibration and destroyed rear transmisswion and pinion bearings seem to be the norm.
Greg Surfas
Please clarify. Are you saying that going with a conventional drive shaft might lead to rear differential damage?
The double Cardin joints are used to lessen the "off center" angle at both ends, and simulate a straight torsion at each end (trans and diff). When you eliminate the 4 u joints you greatly harshen the angle the two ends have to work at adding undue strain in a non parallel plane. The short answer is yes.
Greg Surfas
Hello Impalaman,
I heartily second Greg's caution about replacing the driveshaft with one that does not use the double Cardan joints! Please consider reading the available literature on the physics of the double Cardan joint, and why Cadillac went to the extra expense of engineering them and installing them in their cars.
If the transmission shop doesn't like double Cardan joints, can they explain why, and can they demonstrate how a single u-joint driveshaft is superior? Google Thompson Coupling to see the inherent drawbacks in single u-joint, double Cardan, and constant velocity couplings. Many engineering designs are compromises between performance and cost. I think Cadillac did well to equip their cars with double Cardan joints.
Admittedly you are "shotgunning" your efforts to resolve the vibration issue. How much money have you spent? Are you willing to spend thousands more? I just re-read all 8 pages of posts on this thread but I don't recall seeing that you checked the drive-line angles, or that the driveshaft and transmission repair shops did that for you. The shop manual may or may not describe how to check drive-line angles. Also, the shop manual may or may not describe the procedure for checking the frame. Has that been done? A T-bone collision at a rear quarter could damage the wheel bearing, the differential, and distort the frame. Your car is 45 years old. Despite the back story, unless you have kept an eye on the car for all those years - like Jon S. has with his '58 - you have no way of knowing positively that the car has not been in a collision. One of your earlier posts mentioned that the car was maintained at a Cadillac dealership. This may be the case, but what explains the bad ball joint, and the stripped/replacement pinion flange bolts?
Please take my observations constructively. My point is to help you consider that a methodical analysis and diagnosis will probably be less costly, and might actually resolve the problem.
Respectfully submitted,
Christopher Winter
Plus, in expensive Washington, DC where I am it only costs $400 to have the rear differential re-built on a 1970 Cadillac (have had two of them done), and your 1971 should be same 2.93 rear diff. If you have not done that, probably should before going to a different drive shaft. Plus you have already replaced rear suspension bushings so bolts are not frozen - should be an easy removal.
If a less expensive one piece design would have worked, been quiet and durable - likely Cadillac would have done it. It is very difficult to improve on the Cadillac design that cost many millions 45 years ago to design. That is why I like the 1959 thru 1979 Cadillacs so much, they are unequaled today, and fairly great as they were made new from the factory. Of course there are some improvements: radial tires, electronic ignition, and a few others, but not many things - certainly drive train is great already - don't recommend a modification.
OK gentlemen. You talk a good game. I will reconsider. :)
To answer Mr. Winter's questions, no the drive shaft angles have not been checked nor has the frame.
I will need access to a "drive-on" lift to check the angles. My lift at home is a two post.
I've been all over this car and I cannot see any evidence of a major impact.
I will see if I can get the driveshaft angles checked next.
Been reading this page:
http://www.hotrodhotline.com/md/html/drive_shaft_harmonics.php
Specifically this paragraph: "If there is vibration under acceleration, you need to add more downward pinion angle preload. If the opposite occurs, the vibrations tends to decrease or disappear under acceleration, you need to reduce the downward angle preload."
What does the author mean by "downward angle preload" ?
You know, it is not a very common occurence, but it IS possible for the welds on the upper and lower control arms to crack. You might carefully check all the welds on the rear suspension as well as the rest of the chassis.
Greg Surfas
Hello Impalaman,
That article more or less describes why you should stay with the double Cardan joints, and not opt for a replacement driveshaft with single u-joints at each end.
Downward angle preload (not the best wording) should refer to positioning the axis of the differential pinion +/- 1 - 3 degrees different than its current position relative to level. If your differential pinion was pointed straight up at the sky, the angle between the pinion axis and level would be 90 degrees. Moving the pinion axis (by rotating the differential) closer to or away from level changes the angle.
Rotating the differential is a function of rotating the entire axle housing, which can be done by shimming/adjusting the rear suspension control arms in some cases. By design, I think the Cadillac rear suspension is not adjustable, so if your driveline angles are off, this is most likely due to worn or bent suspension components, sagging springs, wrong shocks or tires. When a car accelerates, the action of the axles/tires against the road cause a reaction against the axle housing and differential. The front of the differential/pinion flange is thrust upwards a small amount. This small amount may be just enough to exceed the design spec of the driveline angles for your car.
Driveline angles should be checked when all rear suspension components (including springs and tires) have been determined to be in good condition, (visually, road test, frame check of ride height). The trans and motor mounts also need to be in good condition. The shop manual for your car should have the frame check and ride height data.
Respectfully submitted,
Christopher Winter
Excellent information.
Let me review what I've done to the drive line and suspension:
- All four rear trailing arms have new bushings. Recently replaced.
- New shocks. I used Monroe OEM Spectrum (http://www.monroe.com/en-US/e-catalog/5815)
- Transmission mount as well as engine mounts are new.
- Transmission rebuilt (smooth as silk)
- Tried new rear springs but went back to original springs.
Let me talk about springs for a minute. I actually ordered the "heavy duty" springs listed on rockauto.com for this car. It was a mistake. While they were visibly shorter that the stock springs, they were much stiffer. The result was a Cadillac which looked like an early 70s hot rod. Remember when hotrodders would stick the rear end of a Camaro or Mustang high in the air? Anyway the rear of the car was very high..... several inches in fact. I decided to test drive it like that and low and behold NOTHING happened. The vibration remained. I reinstalled the stock springs and the car sits nice and level.
Now am I correct in assuming that those stiff springs changed the driveshaft angles? I would think that as the rear of the car goes up, so would the transmission tail housing. Thus the angle at both the trans and at the pinion would be greater. Furthermore as you accelerate it would be less likely
for the driveshaft angles to be minimized.
What does this situation tell us? Comments welcome.
The change of elevation (of the pinion) is spread through the 4 u-joints in the 2 carden joints and each u joint "sees" 1/4 of the change. That is actually less than what occurs when the car goes over a stiff bump.
Greg Surfas
Hello Impalaman,
I am not understanding something in your most recent post. The post stated that the new springs were visibly shorter than the stock springs, yet the rear of the car was higher when the new springs were installed. Assuming that you are referring to the free height when noticing that the new springs are visibly shorter, this would imply that the loaded height of the new springs was much greater than the loaded height of the stock springs, further implying that the stock springs are so soft that they are compressing several inches more than the new, shorter springs when loaded. Without knowing the free and loaded height of the springs, the only conclusion I can draw regarding the springs is that your stock springs are so worn out that they are just barely able to keep the car (without any payload) at a level height.
You are correct that taller installed rear springs would change the angle of the transmission output shaft, since the transmission carried by the frame, and the taller springs would elevate the frame in the rear. However, if my geometry is correct, the angles will decrease (when measured at the bottom of the shafts) - the decrease being relative to 180 degrees. The angles would be moving away from axial alignment, so one would intuit that vibrations might get worse.
Without knowing the baseline angles, or the spring height measurements, or the frame status, it is difficult to make any hard and fast conclusions. If you want to spend some money, I would suggest purchasing a good inclinometer. Find a dead-level parking place for your car. Remove the driveshaft and place the inclinometer on the face of the transmission output shaft and pinion flange. Subtract 90 degrees from these measurements to give you the +/- degrees from level. Replace the driveshaft and measure its angle. Do the math and see if the angles are within specification. I think it should be 1 to 3 degrees.
Your post stated that you have new trans and motor mounts. While I don't think the '71 the Cadillac rear suspension is adjustable, the transmission mount is adjustable using shims. Given the age of your car, you probably have no way of knowing if it came with shims from the factory. Measure the angles to see if shims might help resolve your vibration issue.
Respectfully submitted,
Christopher Winter
I have a photo of the two springs side by side that I can post later. The new heavy duty spring was made out of noticeably thicker rod stock. I compared
the two with calipers and the difference was substantial. As such, while the older spring was taller, it's thinner material has a softer ride. With the stock springs in place
the car sits level.
With the new heavy duty springs in place, the rear of the car sat quite a bit higher due to the extra thickness of the steel, regardless of the fact that the spring was shorter by about an inch or inch and a half.
In addition to checking drive shaft angles , which I plan to do very soon, I purchased a Steelman Wireless Chassis Ear. I plan to place wireless microphones around the chassis in an attempt to determine the point of origination of the vibration.
https://www.amazon.com/STEELMAN-97202-Wireless-ChassisEAR-Diagnostic/dp/B00123J79O
My factory service manual contains ride height measurements I can take as well. Now all I need is the time.
I used an inclinometer on my smart phone.
Trans tail is tilted 5 degrees downward.
Driveshaft tilts downward toward the ground at 1 degree.
Pinion flange is tilted downward toward the ground at 7 degrees.
Hanging threads are annoying, much like this problem has been. Long story short, the car has been normalized. Stock
springs were reinstalled.
A while back I bought a Steelman Wireless ChassisEar.
https://www.amazon.com/Steelman-60635-Wireless-ChassisEAR/dp/B07K3XZR7R
I recommend this gizmo.
I used this device to search for the noise while making multiple test drives and changing
the position of the sensors.
Finally I placed one of the sensors on one of the flanges on the pinion housing.
Once I reached the problematic speed and torque situation, I was able to hear that the problem was coming
from the pinion housing.
I don't have the tools to rebuild the rear end so I plan on taking it to a shop to have that done before too long.
This problem was very difficult to diagnose. It only occurs above 45mph under load.
It is speed and torque related.
Examples:
If you romp on the loud pedal out on the highway to pass someone, it gets REALLY loud.
Going up a slight hill at any speed above 45 will make the noise.
I suspect one of the bearings in the pinion is at fault. Regardless I'm taking to a pro to fix.
Cheers everyone.
Like a dog on a bone, you won't (and didn't) let it go.
Great to hear you've narrowed it down and thanks for the recommendation of the noise locator! Well done. I bet that tool can be pretty handy.
8)
Interesting. So the jumper cable looking clamp must contain a contact microphone? And that style of clamp must just be the most universal type of clamp they found? These days you would think you could also get a camera and display in the same size packages for double the diagnostics.
Indeed. Camera tech is everywhere now. Adding cameras to this tool's capabilities would be pretty awesome.
So I let this project sleep for quite some time while I restored my Mercedes. LOL.... sorry guys.
HOWEVER .... the time has come and I am right in the heat of the battle rebuilding the rear diff and
pinion on this 71 Deville. I now know why (in my opinion) you don't see these cars on the roads
like you do other classics. The rear ends on these early 70s are somewhat of a more rare beast.
I have never rebuilt a rear diff or pinion before so keep that in mind.
At the expense of preaching to the choir, here are my observations:
- This pinion and carrier on this car was LOOSE..... and I mean LOOSE... as in NO PRELOAD.
- This had to be causing the vibration.
- All of the bearing races I removed from this rear end had visible chatter marks. You could not feel
them with your finger nail but you could see them.
- NO ONE makes a pinion crush sleeve for these cars. I cannot find one anywhere.
- NO ONE makes a pinion bearing spacer either.
- Again I am talking about the early 70s Devilles.
- These rear ends use a straddle type pinion which is somewhat similar to the GM truck 14 bolt 10.5.
https://www.youtube.com/watch?v=y3sXMW1CMVs&t=69s
Resultant plan of action:
I decided to go with a bearing spacer and shim stack because of the lack of parts availability.
At least if I have to disassemble the pinion again, I could put it back together and not worry
about finding a crush sleeve. The inner pinion bearing is an HM89449 so I looked at other vehicles on RockAuto which also use that bearing as their inner pinion bearing. Logically any crush sleeve or bearing spacer for vehicle X should match the ID that I need for my car. Also since crush sleeves are 100% vehicle and/or application specific, finding an exact match for length as well as ID was a very long shot. So I decided to find a vehicle for which the inner pinion bearing was an HM89449 AND there was a recommended bearing spacer and shim kit available. The idea here is that it should be possible to cut the spacer down to the length you need.
I found that a 1974 Chevy K10 truck used the HM89449 inner pinion bearing and that pinion bearing
spacer kit "USA STANDARD GEAR USA55046" was available.
https://www.rockauto.com/en/moreinfo.php?pk=4031406&jsn=726
This spacer has a very slight taper on it so that it mates nicely with the HM89449 inner bearing and the
M88048-A outer bearing.
I had the original crush sleeve which came with the car and it was .701 in length. I took the new spacer to a local machine shop and had them cut it down to .701 on a lathe on either side of the taper to retain the proper bearing mating services.
The pinion preload on these cars is 22 to 30 inch pounds.
So right now I have finished a long process of tweaking the spacer and shim stack to obtain preload in the mid 20s (24, 25 etc...)
I ended up using a rotary hand sander in my bench vise to trim down the spacer to .675 in length. I then added a .014 shim stack to get .689 total spacer length.
This gave me the preload I needed. At this point I still need to finish rebuilding the carrier assembly as it is now completely apart as well.
I just wanted to stop by and talk about what I found and the progress made. The stupid pandemic slowed things as well.
It's clear to me now that parts availability for the rear ends on these cars is a big part
of why you don't see many of these cars on the road.
Try searching for a crush sleeve for an early 70s Deville. Let me know what you find.
If you feel so inclined you can check out the videos I made on getting rid of the vibrations in
this car over on my Youtube channel. Look for Impalaman's Garage. I have a play list entitled "Finding Resonate Drivetrain Vibrations".
Cheers.
The vibration is FIXED!
AFTER 7 YEARS !!!!!!!!
This car was defective from the factory. After discussions with a local classic car restoration company (Impatient Creations - https://impatientcreationsinc.com/) and discussions with PMT Fabrication (https://pmtfabrication.com/) I have found that the pinion angle was wildly off.
I replaced the stock rear trailing arms with adjustable ones from PMT fabrication and fixed this issue finally.
The driveline working angles were wildly off. Below 45 or 50 mph it was ok to drive but anything above that was horrible.
I've documented my findings with the driveline geometry here:
https://www.youtube.com/watch?v=Vnt7fvkIrtI
That is the last video in a series I made. The last two videos document my findings in the driveline geometry.
I personally believe that this car was assembled incorrectly at the factory. I do not believe that the trailing arm mount points on the rear axle were welded in the correct spot.
I did rebuild the differential as noted in the previous post but this did not correct the problem. Hope this mess helps someone.
This 9-page thread is hugely helpful.
I've been after a similar issue in my 66 Fleetwood since I've had the car. I've done everything except pinion bearing and the two bearings in the rear of the tranny. I never thought of replacing the rear trailing arms and didn't know there were adjustable ones avaiable.
My noise manifests itself as a road speed related vibration but isn't. It's noise only. When I'm driving with the windows down, it's not there. I don't really notice much until I'm over 85 or 90 and then it's more of a buzzing sound. However, the driveline isn't as smooth as it should be for a Cadillac as it feels a bit gritty or granular.
I've had many B and C body GM cars in my life and have never experienced this before. I've worked at a new car Cadillac dealer during the period when my 66 was a new car and then an Olds dealer after, also here in Columbus, but in the parts dept at both dealers. I drove many of these C-body cars but don't recall ever experiencing such a thing.
Never thought of trailing arms though.
Howdy Scott. Glad to know someone is reading this thread at least. LOL
Might want to measure your driveline angles. You never know. I used a magnetic digital angle finder from Lowes. Works well.
Quote from: impalamansgarage on February 02, 2023, 03:43:01 PMHowdy Scott. Glad to know someone is reading this thread at least. LOL
Might want to measure your driveline angles. You never know. I used a magnetic digital angle finder from Lowes. Works well.
I have one of those that I've used to set the rake on my electrostatic speakers, which are a real bitch to position optimally.
I've tried so many things that I can't remember if we checked those angles or not. I remember that we talked about it, but at age 80, I'm not sure what we did about it.
I have a talented mechanic at a nearby Chebbie dealer who helps with it.
I live in a geezer HOA of single-family homes that are fairly close together, so my compressor and air tools are highly frowned upon. So if it's going to noisy, I have to take to the dealer.
I thought with the double cardan joints on each end of the driveshaft that the angle was not that important. I suppose if it was extreme, then it might be a problem.
Quote from: klinebau on February 02, 2023, 04:14:43 PMI thought with the double cardan joints on each end of the driveshaft that the angle was not that important. I suppose if it was extreme, then it might be a problem.
I thought that's the main reason they used them.
Congratulations on letting everyone know what the solution was.
When I was chasing a similar problem in my '60 CDV, it turned out to be the upper Ball Joint that was totally worn out.
Bruce. >:D
Here are the old and new measurements for reference:
Angle Measurements Before adjustments:
Engine/Trans 6.5
Drive Shaft 1.8
Pinion 8
Engine/Trans/Drive Shaft Working angle: 4.9 (6.5 - 1.8 )
Drive Shaft / Pinion Working angle: 9.8 (1.8 + 8 )
Difference: 5.1
The difference between your working angles should be less that 1 degree as you know. Also with a typical
single u-joint style drive shaft, the measured angle needs to be 3 degrees or less. The way
these cars are put together makes this impossible. Thus GM used double cardan on each end in a W configuration. So that 4.9 degree angle at the trans is actually OK since it gets cut in half by each
side of the double cardan. (in my mind....)
Changes:
I took a lot of that up-tilt out of the pinion with the new adjustable trailing arms and now
the angles are:
Engine/Trans 6.5 (unchanged for obvious reasons)
Drive Shaft 1 (changed be default when I adjusted the pinion)
Pinion 4.5
Engine/Trans/Drive Shaft Working angle: 5.5
Drive Shaft / Pinion Working angle: 5.5
Difference in working angles is basically zero. (Assuming a $30 Lowes digital
angle finder can provide less than half a degree of accuracy is a bit silly but oh well.)