1971 Eldorado odometer - very strange

[Cadman-iac]

Ok, these two pictures show the number rolls from each side. On one side you can see that there is a continuous ring of teeth on the inside edge.
On the other side,  each roll has just two teeth spaced one tooth apart.
Also notice that little metal spring ring there. This is the piece that allows the trip meter to be rolled back. I'll explain more about this later.

[Cadman-iac]

This shows the gear retainer and alignment segment for the odometer. There's at least 4 different designs of these, and I don't know for sure which one you are going to have in yours. My guess is it's the one in the middle. This one has a small spring steel piece that keeps the gear pressed against the number roll teeth.
One of the other designs has the gear actually attached to it with a rivet. And the other one in the picture just has two slots in it for the gear to fit into. I think this is one of the first designs.
You can also just see the thin piece that goes over each of the alignment segment tabs. This is usually made of either paper or plastic, and can be shaped a little differently from the one in the picture.

[Cadman-iac]

This one shows the shaft that the rolls and the alignment segments go onto.
Notice the steel shift has a groove cut along its length. The other one doesn't have it. This groove is for the spring ring that I mentioned earlier.
Also,  this particular shaft with the groove is for a trip odometer. I don't have any of the 79 Eldorado pieces. Apparently the Eldorado that year has the main odometer and the trip meter spread out a lot farther than previous years. But for demonstration purposes, these are fine.

[Cadman-iac]

This one is a main odometer,  but I show it because you can see the thin segment alignment piece on the bottom. This piece helps keep all the segments in alignment until it is placed into the speedometer housing. Without it, getting this into a speedometer and having all of the numbers in alignment and working properly is extremely difficult at best.

[Cadman-iac]

I'm guessing that you had to take your trip meter apart at least some to get that new drive gear onto it. If you did, you may have removed the segment alignment piece and had one of the small gears skip a tooth. This is usually what causes the number misalignment.
What I have done in the past for this is to try to separate the offending number rolls and attempt to get the small gear into another position.  Sometimes it works, but more often than not, it doesn't,  and I have to disassemble the whole thing and start over.

To do this from scratch, first you want to lay out all the pieces in the order that they have to go together. Pay special attention to the pieces as you take it apart, like the shaft, if it has the same shape or grooves or rings on either end. If you have the one with the groove cut the entire length,  look closely at it as this groove has a tapered side and a squared side. You might want to mark it with a pen or something so you know which end is which.

I'm not sure what your trip meter layout looks like,  which end has the drive gear, and what if any spacers or retainers are used to hold the pieces on the shaft in the right positions, so I'm going to start with the tenths roll and go from there.  You will have to do the pieces that go out from there in the order they were in for your particular car.

At this point, I need to mention the spring ring piece. It goes onto the number roll on the right side, the side with the continuous ring of teeth, and the little hook on the inside lines up with a slot in the roll. You can see it in the picture right by the hole in the center of the roll. If yours has these, each roll will have one.
The way this works is the hook is caught in the groove on the shaft and it will let the number rolls spin in one direction when driven by the speedometer cable/gears inside, and show your accumulated mileage.  When you go to reset it you actually turn the shaft backwards from its normal rotation, and in doing so, that spring hook catches in the groove and rolls the odometer back to zero. If  you look at the picture of the shaft, you can see that one side of the groove is squared,  so that the ring hook will catch in the groove when the shaft is rotated the opposite way.
When it's being driven normally by the speedometer,  the tapered side of the groove allows the spring ring to skip out as the number roll is rotated as it adds your mileage.

Edit: if anyone has been following along with this,  you may notice I've made a couple of changes to my explanation of how this works. I wad studying it some last night and realized I had misinformed you all about the purpose of that spring ring and the groove in the shaft. So you might want to reread my posts. I do apologize for my errors,  and hopefully I have gotten it corrected.

[TJ Hopland]

Lots of good info coming out here.   Will have to remember this if I ever need to get into one of these.    Wonder what happened to David?  Maybe he is busy test driving the car to see how it behaves?   Didn't catch where he lives so maybe its nice cruising weather?    My area we have got a few teases of nice weather but then it turns back to normal.

[billmorrow]

FWIW i would never trust an odometer reading on any car over 25 or 30 and for sure not on ei ther my '59 or '70..
better to look at wear on the gas and brake pedals.. wear on the driver seat outboard edges.. worn out driver door latch.. wear on the carpet under the gas pedal..

[Cadman-iac]

In this picture you can see that the spring ring is installed on two of the number rolls/wheels. The spring is easier to see on the white one, and you can see how it goes under a couple of tabs that stick out on the outer diameter of the roll.
If you're going to take one of these apart, try not to remove the spring ring unless it's not sitting in the roll correctly.  It's really easy for one of these to go flying if you're not careful. I learned that the hard way.
The second picture is the other side of the number roll showing the spring ring hooked under the tabs.
Also, if you do have one out, notice the direction it fits on the roll. Towards the top left of the roll in the picture you can see a taper that helps keep the spring in place.

[79 Eldorado]

I'm guessing that you had to take your trip meter apart at least some to get that new drive gear onto it. If you did, you may have removed the segment alignment piece and had one of the small gears skip a tooth. This is usually what causes the number misalignment.

Rick,
Thanks for the detailed information! As I recall I had to only pick-up on one end of the trip OD barrel to get the shaft with the replacement gear in. I'm certain I never removed anything from it and I never separated the layers. When I zero it everything lines up perfectly. The only time anything is off at all is when the next number is transitioning. I haven't driven since I put it away last fall but it seems like it was only the "ones" segment. As long as it's working I don't focus too much on it.

What I have done in the past for this is to try to separate the offending number rolls and attempt to get the small gear into another position.  Sometimes it works, but more often than not, it doesn't,  and I have to disassemble the whole thing and start over.

Since I never separated anything and I believe I just rocked/ pivoted one end up slightly to insert the shaft with the new gear I wonder if what I'm seeing is normal. Based on your last sentence it seems like, if I mess with it, the probability is I may make things worse before I make things better. I think you convinced me to leave well enough alone... too many other bigger fish to fry

Thanks again and great that this is documented as it may help people in the future.

Scott

[Cadman-iac]

In this shot it shows how the small gear and the spring fit onto the alignment segment. The tab sticking out in the 2 o'clock position lines up with the number 5 on the roll when you are assembling this. The gear will be facing away from you.
Also,  remember I mentioned that the gear has a side with 2 different height of teeth on it. This uneven side faces to the right.

[Cadman-iac]

Scott,
I know what you are referring to,  I've seen it before myself. I think that's just caused by the wear in the pieces of the assembly. I'm not sure if there is anything you can do to stop this issue short of completely going through it, and finding parts is impossible.
  If you try to lubricate it that might only make it worse, and maybe cause other issues as well. And I don't know if there's even anything you can lubricate it with.

So should I continue with this,  or has everyone been thoroughly bored with it now?

Rick

EDIT:
This can be a very tedious task, and you may have to do it several times before you can get it right. It took me a while and I have lots of pieces that I have been collecting for years to even have enough to try some of this.

One thing I played around with was adding that 100K digit to a couple of my own trucks. So now instead of just rolling over at 99,999.9. , they continue on like the trucks from the late 90's and on. It took a bit of work, but it works great, and to me it's worth the effort. I even added the electronic cruise control that picks up the spinning of the speedometer head, so I've eliminated the transducer and split speedometer cable setup. That works great too. I made a template for the back of the speedometer so I could accurately drill the holes necessary to install the pickup sensor for the cruise. I'll post a couple pictures of it just for reference. The cruise control modification can be made without too many problems.  The only thing you need to figure out is where you are going to put the switch that normally goes on the turn signal lever. Everything else can be hidden so only you know that the car has a later model cruise control on it.

  I would try adding the extra digit on my 56 but I just don't have enough of the parts to do it,  and it's very time consuming. But it would be a great thing to have. Then there wouldn't be any question as to how many times it's rolled over.

[79 Eldorado]

I updated my thread (link below), on the '79 Eldorado, to include a link which people can follow to this thread since it has so much helpful related information.

Rick,
I missed a key post on the first page showing those smaller gears between the segments. Seeing that photo helped a lot.

http://forums.cadillaclasalleclub.org/index.php?topic=152268.msg409432;topicseen#msg409432

Thanks again,
Scott

[Cadman-iac]

Glad to be able to help Scott. If you have any questions, please let me know and I'll try to answer as best I can.
Thanks for listening/reading, and good luck with your trip meter. And thank you too for the link. I didn't realize that this information was that hard to find.

Rick

If anyone is interested in this, please let me know and I'll continue with it tonight. My thanks to all.

[79 Eldorado]

Scott,
I know what you are referring to,  I've seen it before myself. I think that's just caused by the wear in the pieces of the assembly. I'm not sure if there is anything you can do to stop this issue short of completely going through it, and finding parts is impossible.

It would need to be modeled from measurements but if the gear between the segments is what is worn a 3D printed part would probably work.

  So should I continue with this,  or has everyone been thoroughly bored with it now?

Rick

I think this site should have a technical section with a "sticky" for informative threads which go through the time and detail of explaining things like this... so I don't know about others but I'm not bored. Between different cars, tractors, appliances etc I cannot explain how good it feels when you find good and complete information on whatever you are working on.

... One thing I played around with was adding that 100K digit to a couple of my own trucks. So now instead of just rolling over at 99,999.9. , they continue on like the trucks from the late 90's and on. It took a bit of work, but it works great, and to me it's worth the effort.

You may not believe this but adding the 100K digit was exactly what I was thinking of when you first started explaining how the parts were working. During an inspection I've had people read the OD wrong and mostly because everything has the 100K segment now. So if anyone ever does Carfax the readings will look really strange and it's not because there was anything nefarious going on it's simply someone read the odometer wrong. So as an example 04096 becomes 40,960 so the following year it looks like you drove +60-70K miles!

I even added the electronic cruise control that picks up the spinning of the speedometer head, so I've eliminated the transducer and split speedometer cable setup. That works great too. I made a template for the back of the speedometer so I could accurately drill the holes necessary to install the pickup sensor for the cruise. I'll post a couple pictures of it just for reference. The cruise control modification can be made without too many problems.  The only thing you need to figure out is where you are going to put the switch that normally goes on the turn signal lever. Everything else can be hidden so only you know that the car has a later model cruise control on it.

Very cool!

Scott

[Cadman-iac]

Yeah, i thought it would be nice to have the extra digit on all cars. It would hopefully eliminate a lot of doubt about how many miles a vehicle actually has. The one big problem with doing this to these older Cadillacs is that the speedometer face is usually polished or chrome if i remember right.
On my trucks all i had to do was cut the "window" open so you could see the new number. The speedometer face is black and only made of thin metal,  and the lens is open and doesn't hide anything on the left or right sides of the odometer. 
On the Cadillacs,  the odometer window is a little bit harder to open up and make it look nice. If you screw it up, then you need a new face piece,  and they ain't easy to come by.  I do actually have 3 speedometers, 2 for a 56, and 1 for a 55. But I'd have to be really sure about it working before I would even consider cutting out a face plate.
The other thing is that if memory serves, the shaft on my truck odometer was long enough to accommodate the extra digit.  I don't know if there's room for an extra one on the Cadillac odometer shaft.
As novel as that would be,  it  just takes too much time and effort to accomplish, and i have so many other things that need to be done that I can't justify the time to do it, if you know what I mean. I'm going to be 61 next month,  and who knows how long I will be able to keep doing this stuff, and I would really like to get to drive my car before I die.

[79 Eldorado]

Rick,
You hit every nail right on the head. Parts are just not easy to find if you accidentally slip and mess something up..plus the original finish. One of my first cars was a 9 year old 1979 Toronado. I liked it a lot because I could always find junkyard parts at the time. I used it for everything even Auto-x racing (not an ideal car for that). When things started breaking as the car got older I decided I needed to reserve it for a nice normal driving car because parts were becoming increasingly hard to find. There is an axle support bearing on that car which is the same as the one on the Eldorado. That's a 5-10 dollar part but a necessary part. It's also a part which was impossible to find even in ~2003 when mine went bad. It was a GM only bearing but it was identical to a standard bearing except the ID was something like 8-10 thousandths of an inch larger than standard. At the time I was very lucky to be in contact with a die shop that had a center grinder for hardened materials.

Like you alluded to there needs to be time to drive these cars and working on them constantly takes away a lot of time. I would even say to anyone who is new to the hobby find one special car that you really like and don't buy several (one plus a daily driver). It just spreads a person, who isn't Jay Leno, too thin. Everything needs maintenance regardless of how often it's driven. Now if I could only follow my own advice I get too attached to them though so it won't likely happen any time soon.

Scott

[Cadman-iac]

Ok, just a brief bit about these pictures.  The first two are an example of what the anti-tamper part of the regular odometer looks like. You can see it has a half round arm on it on the outer diameter, and it has a small tooth that engages the first number roll. This is on the right side of the odometer, and turned in one direction it turns the numbers over on the odometer, adding mileage, but turned the other direction, and that arm will deflect and it will skip over the teeth on the number roll, preventing the mileage from being rolled back by trying to drive it in reverse.
If you have an odometer that doesn't work at all,  this arm is probably broken or bent to the point that it won't engage with the number roll.

The third and fourth pictures are a couple of different designs of the anti-tamper gear that GM also used. Im not sure now what years they are out of, as I have only kept the small gears and pieces of the speedometers I've parted out. I keep this stuff in case I ever need it for a repair, or as I did in my trucks,  I modified them and added another number to the odometer.

[Cadman-iac]

These two pictures are of the drive gear that engages the first number roll. The one on the left is a later style like what would be in a 70' or 80's Cadillac. The one on the right is an early style, this particular one is from one of my trucks,  but I believe that Cadillac used one similar to this in the 60's, but I'm not positive of that.

[Cadman-iac]

more to follow tomorrow.

[79 Eldorado]

The outer ring anti tamper part looks like a nice design. They gave it a very long arm so that the total fixed displacement, required when the tooth jumps, can occur over a long distance to hopefully last many cycles.

Scott