1956 Jetaway will not engage

[Lexi]

Bob thanks     If you are stuck in the midst of a trany project and think a few snap shots from this manual will help, let me know. Don't want to copy the whole thing as is large, but can post some specific pics to "Lend a Helping Hand", as Lynyrd Skynyrd used to say.    Clay/Lexi

[Bronze]

Update: Cleaned out the valve body and accumulator/servo. Valve body was dirty but no stuck valves and no completely congested channels, But still a layer of gunk in all channels. Servo piston had a really thick layer of hardened gunk on top(10mm half inch like), enough to stop it from moving all the way up i would say. When i put it all back and tried to put the car in gear at first it behaved as before moving weakly backwards no matter what i did. Put the rear up on jack stands and tried again and suddenly it was like something came loose! Wheels started spinning forward in Dr and backwards in reverse. It was also shifting, not sure if it was through all gears but I had shifts. And when i moved the shifter to Lo it definitely downshifted. Revs went up and speedo started falling. I would say that now it kind of works in regards to shifting. Remaining problem is that when i took it down from the stands it was still slipping badly. I can move forward and backwards on a flat concrete floor but it takes something like 1500-2000 rpms to make it happen. I know the sensible thing to do long ago would be to get the tranny out for a complete overhaul but since i like to tinker this way i thought I'd ask if there would be anything else i could check in regard to the weak pull i get from it. Does it all point to worn out clutch disks or could it be a fluid pressure thing?

BR
/Martin

[Roger Zimmermann]

If you have the possibility to measure the oil pressure, do it.
You probably don't know if or when the transmission was overhauled; rubber seals are getting hard with time. Some early '56 transmissions have steel seals at some pistons; they will never leak, but the are still rubber seals which should be replaced. There are also hard parts which can go bad...

[Bronze]

Yessir! will do. Can you tell me where i find the attachment point for the gauge?

I also learned there is an externally accessible pressure regulator, will take that out and clean it. Is it correct that i could start the engine and rear wheels on jacks with a pan underneath to fluch the regulator?

[Bronze]

flush not fluch....

[Roger Zimmermann]

This the small bolt located at the under side from the rear oil pump. See the attached picture. I cannot mark it with an arrow, I'm not at home.
This is not a picture from a '56 transmission because the output shaft is shorter than 1956, but the location of the bold is the same.

[Bronze]

Got it! Thanks Roger. Meanwhile i can report that the idea of starting the engine with the pressure regulator valve out was not a good one. Well it flushed allright, but the cleanup afterwards was no fun....On the other hand the car pulls much stronger now. Need to service brakes and check oil pressure, them it is test drive time!

[Bronze]

Alright, with fixed brakes i took her for a test drive. My oil pressure gauge did not have the right thread to connect so that is not done yet, but maybe it is not needed.
This is how she behaves now.
When i put her in gear the transmission pulls weakly or slips badly. Even if i rev hard the car only creeps forward ( or backward) but if i persist until i reach like 30 km/hour all of a sudden i get a distinct shift and she starts moving forward strongly. I am guessing that the front pump is not giving pressure but when i reach enough speed for the rear pump to kick in i get pressure and it all starts to work. Does that sound right? I had the opportunity to reverse in a downhill slope but i don't get that feeling that the car gets stronger with higher speed when i am reversing even if i did reach the same speed. Roger pointed out that the servo and the band is just working in reverse and Lo. Does that mean when the shift selector is in Lo or should the band operate in low gears even if the selector is in Dr?
Will i seriously (further) damage the transmission having it slip that badly while getting up to the speed when it engages fully?
If Chuck is still reading this thread: Since you enjoyed my description of the rear on jacks with neighbors watching.... Now picture this...2500 rpms, barely getting out of the driveway...creeping along the block roaring engine getting passed by kids on tricycles until all of a sudden Jetaway engages with a necksnapping lurch forward. Refusing to let go of the gas pedal and slow down I'm taking next corner at 40 mph, not slowing down, passing those damn kids with an evil smile. 30 seconds later comes back in reverse...creeping at 3000 rpms...
What is the verdict? Front pump? Servo/accumulator? Should i just stop and tear down the trans? ( Yeah i should have done that long ago i know. but this is more entertaining )
And by the way thanks all for all help so far!

[Roger Zimmermann]

Well, I see the situation well! There are two one-way clutch in the transmission; maybe one is not holding.
According to the description, it seems that the first gear is absent; when the car is suddenly moving, the second (or third) in on. As I'm not at home, I cannot search why the first gear in not functional. For the reverse, the power flow is similar to first gear.
Anyway, I have only one the answer for that issue: overhaul the transmission before more damage is done. Less entertaining for the kids, but safer!

[Bronze]

Thanks so much for that answer Roger.
And thanks for being so supportive along the way.
From understanding next to nothing about an automatic transmission, I have now with your (and others) help overhauled both the servo and valve body, got the car from not moving at all to get in and out of the garage. And i have learned a lot along the way. So even if the end result is the same it has not been a waste of time. And of course the entertainment factor

[fishnjim]

There's always a reason why they sit, so best to find out before resurrection.  Not counting any damage done during the long sleep.
After 3 pages, I rest my case on not doing trans work.  I had mine done after a part failure and now it's leaking copious amounts, so what have I gained?   It's a major pain to yank one out, without a lift, and the modern shops will laugh if you role up in one leaving a trial of drops/tears pleading for help.   
The sludge issue is common and everyone should take heed when dealing with these dyno-soars.  There's more in it, if it has a fluid cooler.  So a clean trans is a happy trans.   I recall reading an article about GM.  They installed essentially "clean room" conditions in the trans building and failures were almost eliminated.
I guess some trans expert will capture all this info and publish some sort of a guide or process for revival.  A mobile service might be nice...

[Roger Zimmermann]

A mobile service might be nice...

In my opinion, not for those transmissions. When I'm getting one for overhauling, I never order a kit in advance because, if hard parts are needed (like bushings, thrust washers, etc.), I will have to pay again for shipping and maybe customs, making the repair more expensive.
I'm removing all parts, looking at them carefully, and only then I'm ordering what's needed. Sure, if I would overhaul 5 or 10 Hydramatic transmissions each year, I would buy more parts to have all at disposal.
Then, parts are heavy. When I'm "playing" one afternoon with one of those, I'm waiting the day after to continue...
In each transmission I'm doing, I'm investing about 30 to 40 hours with removing parts, cleaning, checking them, assembly, sometimes disassembly again, till the beast is ready. OK, I'm not the quickest, but I'm not doing that for a living.