I have a traditional vibration of 50-60 mph
The driveshaft is balanced, the universal joins have been replaced. The support and the bearing are original, but they are in excellent condition. New engine and transmission mounts. New tail transmission bushings.
I think the problem is in the angles of the driveshaft.I want to measure the angles and correct them.
But I do not understand the following. Is there an angle between the transmission and the first shaft or is it a straight line?
1 or 2?
I don't know of the exact angle, but I'm leaning toward illustration #1. Reason being, they put shims under the carrier bearing support to bring up the angle, The rear shaft pivots with the movement of the rear axle.
Now, do they shim the front shaft section to be in a direct line with the transmission output shaft, or is it raised a few degrees? And those shims are a bear to put in too. Taping them to the carrier support and reinstalling the shaft then driving it is about the only way to find out
If there is no angle between the transmission and firt shaft, the universal joint will be soon dead because it must have an angle to stay fit.. For cars for which the output shaft is amost at zero degree, a rubber with fabric disk is used.
Some years ago, I saw an interesting article explaining how drive shaft angles are managed. Maybe if you try in Google you will find it.
In short, the correct way for your car is the illustration 2.
Now you have two people who responded and two different answers...Who is right?
Is it possible that the shims raise the rear above the transmission output? That way you can create an angle in which to circulate the needles and give the rear shaft more travel.
To get the correct angles in these cars, one has to look really hard at the condition of all areas that have a relationship to the positioning of the Engine, Trans, intermediate drive shaft bearing and Rear End.
When these cars were brand new, they ran perfectly, and as they age, problems arise.
Engine Mounts sag, Trans mounts sag, Centre Bearing mount sags, and all the links at the Diff sag. BUT, many people forget about the upper control arm and ball joint that controls the angle of the diff.
In my '60 CDV, I was chasing the same vibrations, and it turned out that the main culprit was that ball joint. It was totally shot. Notice that the steel hole was out of shape. This joint was that loose.
Bruce. >:D
If memory serves right, I believe, on here, someone resolved this issue by slotting the carrier bearing mounting holes so the bearing would slide sideways a bit to achieve an angular difference.
Wish I took photos of various stuff when I gave Shelley a lucas oil change plus basic maintenance. The biggest thing with any vibrations is the shaft bearing...and it appears that this one was done sometime in the recent past. The rear end ball joint definitely needs replacing but thats a whole animal within itself. Greasing the fittings massively helped with sound quality and ride.
Did you try to put it in neutral when it starts to vibrate?...If so, did it stop vibrating?..Could be the center support bearing?...Unbalanced wheels too?...
I'm having the same issue on my 63. I'm getting a vibration at highway speeds and a knock at low speeds. I've replaced the upper ball joint and some worn control arm bushings and it has improved. Previously at around 20 mph it had a bump that was strong enough to break the seal on the dried up windshield gasket and make the glass bounce. That has gone away. I'm still getting the knocking at very low speed. It sounds like a very worn out u-joint clunking but the joints don't feel loose. As soon as I get my 4 post lift cleared off it's going back in the air to investigate further. When I replaced those bushings about 3 months ago I raised the back tires off the ground and put jack stands under the axle so I could run it in gear and get under there and see if I could find the problem. But the wired thing was, it didn't do it on the lift.
Quote from: Roman_cadillac on February 28, 2025, 05:08:57 PMI have a traditional vibration of 50-60 mph
The driveshaft is balanced, the universal joins have been replaced. The support and the bearing are original, but they are in excellent condition. New engine and transmission mounts. New tail transmission bushings.
I think the problem is in the angles of the driveshaft.I want to measure the angles and correct them.
But I do not understand the following. Is there an angle between the transmission and the first shaft or is it a straight line?
1 or 2?
I would say it's not 1. The front joint needs a little bit of an angle. How much of an angle would be determined by the pinion angle. So I would shim the center bearing to suit the pinion angle and then the front joint angle should sort itself out. Just check to make sure it doesn't exceed about 4 degrees.
#2, Can we assume you have the U-joints in phase? If yes then one source of vibration eliminated in your diagnosis.
Somewhere in the factory manual the angle(s) should be noted. Easy to check now with the inclinometer on an iPhone.
tony
When did Cadillac start using the double Cardan joints? Wasn't that to make things smoother and get rid of the angle problem giving more options for floor heights and such?
1965, tj.
tony
The 63 has two double cardan joints in the rear shaft section. One at the carrier bearing and one at the differential.
I seem to recall some past discussions on this issue here that talked about a special tool for measuring the angles and also referencing a spacer in the trans that is often overlooked/left out during repairs, which can cause vibrations.
I believe the changeover year to the full Carden joint arrangement was 1965. Prior to that only one shaft had the Carden joints. And IIRC they were introduced in '63 or so in the Fleetwood 75s then later the other series. Had something to do with change from the X section frames. My '67 had full carden joints. Expensive to rebuild, but worth the money. Incidentally using the double u-joint application essentially creates a constant velocity joint eliminating vibration. I did some research at the time and what is above is what I remember.
All of this came from when we bought a '67 DeVille convertible in 1994. My sweetie and I turned fifty and our birthdays are a week or so apart. We bought the DeVille for our joint birthdays.
The car had a slight vibration that could be felt in the backseat. I checked the U joints by shaking, etc. and they felt fine. Phasing and angle was OK. Everything else was original. I took the shafts to the driveline shop that worked on my trucks and they disassembled the driveline. THe rear set and one of the front set were brinelled, which is a form of fretting, but had not failed. Replaced them with good quality joints and the vibration was gone. The car rode like I imagined it did when new and near new.
tony