Slipping reverse on a 1959 Hydramatic

[Roger Zimmermann]

Recently, I ovehauled a 1959 Hydramatic transmission. I had to replace the front oil pump, the pressure regulator and the reverse piston among the regular clutches and seals.
Now the transmission is slipping in reverse, forward is OK. There are several causes according to the shop manual:
- reverse piston apply restricted or leaking
- low oil pressure
- manual linkage incorrectly adjusted
- front sprag clutch slipping
- front sprag clutch broken

The transmission had to be overhauled because antifreeze went in the transmission oil. Before this event, it worked fine.

In my opinion, a reverse piston seal was improperly installed (nobody is perfect), creating a loss of pressure for the reverse. Pressure tests have not yet be done, they could help to find the problem.

It's the 4th Hydramatic I overhauled; the 3 other ones are working as intended.

Has someone maybe a different opinion or had a similar experience about the slipping reverse?

Thank you for your answers!

Roger

[Roger Zimmermann]

No second opinion for that case? Where are all the experts for automatic transmission?

[The Tassie Devil(le)]

Hang in there Roger,

I have sent out a feeler and the person should be taking a look as soon as they wake up, and get to a computer.

Bruce.

[quadfins]

I don't know if this is a second opinion, and I doubt it can be considered a diagnosis, but here goes...

I was having intermittent reverse slippage on my '61. Sometimes it would engage, sometimes not. It was especially doubtful after driving for a while - whether it was built up heat or pressure, I don't know. After parking for a few minutes, I could restart and usually get enough reverse to get out of a parking space or manuever back into the garage.

Finally, I had enough, and then I was referred to a local "Good 'Ole Boy, who knows Hydra-Matics...

From my description, he diagnosed it as a broken return spring on the revrse unit. He took the rear unit off, and sure enough, the wave spring had broken into several pieces. They were circulating around within the reverse piston workings. Sometimes they would get wedged in, and reverse would not work. It was apparent that they had been scraping the aluminum piston for some time.

Spencer told me that this was fairly common, from his experience. He replaced the damaged parts, and I have had reliable reverse for the first time ever.

In your situation, however, since your reverse was working up until the rencent rebuilt, I think that it would be a strange coincidence if the return spring just happened to fail now. I wonder if there is some other cause - maybe the coolant contaminated the reverse cone or something. I am a Hydra-doofus, so I can't really diagnose what it might be. But if you are in Tidewater Virginia, Spencer is THE MAN for Hydramatics.

Jim Eccleston
1961 Coupe de Ville

[Roger Zimmermann]

Thank your for the replies. The wave spring was replaced by a new one as the original one was broken. The rear piston was replaced by a used one as the friction cone was no more bonded to the aluminum part.
Seals lips are easy to be wrongly installed; I suppose this is the case. I have the feeling that the transmission has to be removed from the car to get to that piston...
There is all the time something to do!

By the way, I'm located in Switzerland; I will do without your Mr. Spencer.

Roger

[quadfins]

He was able to do the repairs by removing only the rear unit. The main part of the transmission stayed in the car.

I suppose, though, that you have much more experience than me with these things, so you know best what can be done.

Jim

[Ed Mobley]

Recently, I ovehauled a 1959 Hydramatic transmission. I had to replace the front oil pump, the pressure regulator and the reverse piston among the regular clutches and seals.
Now the transmission is slipping in reverse, forward is OK. There are several causes according to the shop manual:
- reverse piston apply restricted or leaking
- low oil pressure
- manual linkage incorrectly adjusted
- front sprag clutch slipping
- front sprag clutch broken

The transmission had to be overhauled because antifreeze went in the transmission oil. Before this event, it worked fine.

In my opinion, a reverse piston seal was improperly installed (nobody is perfect), creating a loss of pressure for the reverse. Pressure tests have not yet be done, they could help to find the problem.

It's the 4th Hydramatic I overhauled; the 3 other ones are working as intended.

Has someone maybe a different opinion or had a similar experience about the slipping reverse?

Thank you for your answers!

Roger

Roger,

I had a similar issue when I rebuilt my tranny, but it impacted my ability to get into 4th gear.  You can read about it at:  www.photopaige.com/edscars

Long story short, I had an undersized oil ring on the front coupling unit.

In your case, I'll bet the seal was installed backwards.   According to the manual, you can pull out the reverse piston with the tranny on the car.  Unless I had a hoist where I could stand underneath the car, I'd remove the entire tranny. 

After my tranny rebuild experience, I've learned to test all the sub-components with compressed air before assembly.

Regards,

Ed