The front unit coupling is stuck; no more!

[CadillacFanBob]

Roger your persistence paid off, I did like your process of welding 3 steel corners to attach puller

Bob

[Lexi]

This afternoon, I welded 3 steel corners to the driving torus and used a good puller. After a while, by hammering the torus, the assembly came out. ...will do pictures soon!

Well done Roger! Looking forward to seeing the pictures. A welder is a very useful tool to have. Please keep us posted on this. Clay/Lexi

[Roger Zimmermann]

Here re some pictures from that transmission. First, the front sprag inner race with remains from the driven torus



Another view



How the driven torus shaft is looking like



A still intact driven torus shaft



My method to extract the driving torus



Don't remember if I ever used that puller, but yesterday it was useful



Some tangs broke very early, this is the reason why the later parts books have only the shaft with splines

[TJ Hopland]

Any theories on what happened?  Was it hammering in and out and broke the washer and that is what was holding it in?  What sets the end play in that assembly?   It kinda seems like it had to be loose and didn't leave much engagement surface.

[Roger Zimmermann]

It's hard to tell what broke the washer. Probably if the washer was no more perfectly aligned, the hammer blows did no good for it. In fact, I don't know exactly why the assembly could not be removed easily. As you can see on one picture, the shaft was seized, probably into the front race; this was no help...
The play for the front unit is done with selective washers. As I will have to use another front unit coupling, I will have to check the end play with the special tool I have.
The first design with the lugs was not very good and was replace with a new design having splines; this new design is bullet proof, but was probably more expensive to manufacture. 

[Lexi]

Well done Roger. Clay/Lexi

[CadillacFanBob]

Great update with photos, Thank you Roger

Bob

[Dave CLC#16900]

Does anyone have a recommendation for a Hydramatic rebuilder near California?  My '56 Eldorado makes terrible noises in reverse and no reverse when hot.  Much appreciated.

[Roger Zimmermann]

Most probably the rubber seals at the reverse piston are old and cracked. Hard to tell why the noise, but it seems that a rebuild is mandatory.

[Dave CLC#16900]

Thanks for the quick response Roger.  Isn't there a piston that is supposed to lock one part of transmission for reverse to work?  It does sound kind of like a sprag that isn't quite locking.

[Roger Zimmermann]

The piston (20.1727 on the attached drawing) is pushing against a double cone (20.1721) which itself is pushing against a stationery cone (20.1730). Indeed, both sprags should be on; if one is not locking, you will have the knocks. If you are looking which sprag is working and when, you will see that the front sprag is on in first and third gear and the rear sprag is on in first and second gear. If one is not working as intended, you should also have a strange behavior of the transmission.
Diagnostic over Internet is hazardous!

[Dave CLC#16900]

Hi Roger,

I drove the car a bit 30 years ago when I first bought it.  Seemed pretty ok at all speeds but it was (and is) the only car I have driven with an early Hydramatic.  Reverse worked pretty good cold.  Hot it made quite a racket and minimal movement.  Have driven it in the last 2 years but just on and off a trailer and uphill into a garage.

Planning on a full rebuild.  Previous owner bought it in 1970 and had the trans rebuilt in 1978.  He said it never was right after that and parked it in 1981 when reverse started to fail.  I bought it in 1990 when I had hair...  Now it is a retirement project.

[Roger Zimmermann]

Those transmissions are working very well if all is OK. I suspect that there is an internal leak at the reverse unit. I had this case at an Oldsmobile (principally the same transmission) which could reverse when cold but not when warm. The transmission was once overhauled, but the seals from the piston' reverse unit had not been replaced and were hard like glass. However, as far as I can remember, the owner did not say that it was noisy. Another possibility for the noise: the piston is not pushing hard enough (reverse is using full oil pressure) and the double cone is grasping, letting go, grasping, and so on. The cone from the piston or the one into the case may be worn and the piston has not enough travel to do its job. The reason will be revealed when the transmission is open.
I still have hair, but they are white!

[Dave CLC#16900]

One last question Roger.  Hope to visit the car (it is out of state) in a couple of months.  It leaked a bit of fluid in 20 years of storage.  Any harm to add some Lucas trans fluid to help the chances of reverse working for some limited driving?  I actually put plates back on it.  Inspiration is important!

[TJ Hopland]

I'm no expert on this era transmission but if the reverse seals are bad so are the rest so none of the clutches are going to be engaging properly and slipping.  Soft parts for these are no problem and not very expensive but if you start to damage hard parts which is easy to do when things start slipping you better have some time to search for the parts and your unlimited credit card ready if you do find them. 

I had one rebuilt about 8 years ago and from the symptom the rebuilder was expecting to find a specific hard part damaged that he said he needed for almost every one he had ever rebuilt in the last 20 or so years.  He said that just before mine he needed one and it was about a 6 month search and $1800 by the time it was shipped.  I don't remember the name of the part but he said it gets hot from the slipping then kinda distorts then cracks.  He said if you kept pushing it he had seen them actually come apart and at that point you might as well be looking for a whole new unit because large chunks of metal floating around don't do the rest of the parts or the case any good.

At the time I had a complete spare transmission that ran when pulled around 1970. Based on his experience he said that chances were real good that one would have good hard parts as long as it wasn't full of water. He actually made me bring that one to his shop before he worked on the car because it didn't want a lift/bay tied up waiting for parts if we needed them. Turned out everything was fine because I don't think it got drove much before we got the car and we could tell something wasn't right so got it into the shop right away. 

Dang those things were heavy.  It was a heck of a job to drag it from my suburban onto his shop cart.   I got it into by burb using a skid steer.  The previous transmission I had that shop do was a C4 and that I could darn near carry under one arm with my other hand free to open doors.

[Roger Zimmermann]

Hope to visit the car (it is out of state) in a couple of months.  It leaked a bit of fluid in 20 years of storage.  Any harm to add some Lucas trans fluid to help the chances of reverse working for some limited driving? 

Usually, all those transmissions are leaking, more or less! Adding Lucas trans fluid will do no harm except to your wallet. If there was an issue 20 years ago, that product will not solve it. Those transmissions are funny: The one I put some pictures in this report was driving well; the sole complain was there is no engine braking in D3...
Another one I overhauled this year had a leaking bowl at the front coupling; welding it was the cure. This transmission had also the neutral drum defective but, as the parts were maintained by the case, there was no drivability issue. But for how long? The front unit coupling did not pass the air pressure test I'm doing on a regular basis but still had 2. and 4th gear.
This week, I took apart a 1960 Hydramatic which had a strange behavior. I found that 3 or 4 discs had no friction material on one side (there are 7 discs for that clutch); the front unit coupling did not pass the test with compressed air because, after removing the cover, I saw that the two thin rubber seals were rather hard and therefore leaking.
All these issues could not be cured with a sneak product!

[TJ Hopland]

Roger, do you know what part my builder would have been talking about?  Also I don't remember if we have been changing the years we are talking about here, mine was a 57. 

[Roger Zimmermann]

Most probably he was speaking about the front unit coupling which had tangs for 1956/57. Since I'm overhauling transmissions (about 30 - 35 to this day) I had "only" two '56 transmissions with the tangs broken like you can see on the pictures. Some '56/57 I refreshed had been retrofitted with the splines system, for what ever reason. Most transmissions I'm getting to overhaul were already opened during their life.

[Dave CLC#16900]

Hi TJ, you bring up some good points.  I do have a spare '56 Eldorado transmission from my parts car with 98k miles but don't know the condition.  My car has 230k miles, but not many since that rebuild in 1978.  Just thinking to drive to the store near the storage site in October.  About 3 miles each way.  I drove it a couple hundred miles 30 years ago.

Still need a good rebuilder in California area.  Car is in Michigan but don't spend enough time there to remove and reinstall a trans.  Car is heading West in a year or two.