Technical Dual range hydramatic rebuild

Just got done doing complete tear down and rebuild on my 54 olds transmission. Sure hope I put all 4,325 pieces back in the right spot and this is my last question.

Someone familiar with these help me out please. I have adjusted both bands internally per owners manual. Front band sits loose on drum and obviously engaged by front servo to tighten band. My question is with the rear band. When I adjust the rear band (tighten) using the gauge to the correct location the band feels really tight and drum will not turn at all.
Once everything pressures up does the servo loosen the band? I would assume both bands should be loose until pressure is applied and not one loose and other tight.

During disassembly it does tell you to loosen rear band adjustment before removing rear servo. So obviously there is some sort of tension on it.



I have heard rumors of a hydramatic group but whenever I click on the link i always get a hamb error.

If anyone has any questions I will gladly help out with what I've learned so far.

 

With no hyd. pressure, ie engine off; the front band and clutch are "off", the rear band is "on" and the rear clutch is "off". This is from my Paul Marsh Hydra-Matic service manual. So you are good to go...

There is a hydramatic group on the hamb, though it doesn't get much usage.

 

Thanks warbird1 !

 

WOW!! That's quite an undertaking.. Good for you...

 

When I was 16, I screwed up the transmission in the family 55 olds 88 with a few neutral drops..laying rubber with those big soft bucron tires. Trans wouldn't upshift anymore.
My dad took the car to work [worked at a Caterpillar shop] and we [yeah, I was included] and we tore it down to bare case....found a broken snap ring and he never found out where it went.
Ended up buying a $25 used trans from the junk yard and it worked perfectly. I didn't drive the car for a few months.

 

You do realize you'll probably be having every Hydra-Matic/Hydro owner wanting you to rebuild theirs now don't you? I think most guys would be willing to try rebuilding one of this if there was't so many "special tools" required as the books seem to specify. Your trans looks like it was't service with any regularity, or sat for quite some time, before you got into it. Good job! I am Butch/56sedandelivery.

 

I just replaced the front seal in mine and I don't want any part of one again.

 

It really doesn't take that many special tools to rebuild one of these. The band adjustment tools, a dial indicator and a couple of large C-clamps are all I've ever used. Biggest PITA are those cast iron seal rings...

 

Yeah I didn't even use c clamps. Just a 4x4 long ways with a 2x4 on top that I stood on to compress the drums. Haha

 

And yeah the trans had 70,000 miles on it. It's a 54. Oldsmobile. Been sitting in storage since 59. Pretty cool the guy was some sort of medical salesman. Drove a car till it broke then just parked em and bought a new one. Still has all the hospital parking tags from 59 all over it.

 

Most bands are pressure applied and spring released. The rear Hydro's band is spring applied and pressure released. One of the best "how it works" movies ever made was the WW2 "Modern Combat Vehicle" made for Ordnance mechanics on the single coupling Hydro, as used in the M-5 medium tank. If you understand how the valve body works, as shown so well in that film, you understand every automatic trans' shifting, even computer controlled. Good action shots, too, of the M-5.

 

Warbird 1 is correct. The rear band is spring applied and hydraulically released. This is why if you turn the driven torus when in any range other than R, the tail shaft will turn.

I have done work in these transmissions, but generally these things are bombproof. You really have to work to break them. I generally seal them up, clean the valve body, and adjust the bands. Other than that, not much else.

 

Nice work, those can be a little intimidating but are really not that bad once you get in there. Re the band adjustment ,as others have said yes the rear band is spring applied and pressure released. That is what allows you to use reverse for parking when the engine is off. The best thing to do is once you get the unit installed, is follow the shop manual instructions re adjusting the bands with the engine running. That is the only way to really get them right. Follow the instructions to the letter. Specifically the order in which things are done. Do it that way and it will be perfect. Good Luck. Randy

 

The rear band is "park" and disengages when there is fluid pressure or once you have fired that bad boy up. At least that is what I have been told.

hey D2, I haven't played with one of these since high school, maybe one day we can converse and you can help me learn or remember, or both. My B&M will love you for it.

 

Park is actually established by a parking pawl mechanism which locks the output shaft to the transmission case. Why the engineers decided to use the spring to activate the rear band is anyone's guess. But it works!

 

It will be very difficult (more like impossible) to adjust both bands while engine is running on 54 up transmissions, as there is no adjusting screw for front band. Preferred method is to drop pan and using proper tools, adjust bands accordingly.

 

This is the Hydro group that @warbird1 was referring to: Hydro Tech (You have to join the group to see all the threads).

And good on you @Itsbiscuit! Quite an undertaking.

 

I think what Pork n Beaner was thinking about, is that some of the Hydros go into park when you shut the engine down, automatically. Others, such as trucks, have to be manually "parked"; accomplished by a parking pawl, or anchor as GM calls it, that engages the notched ring on the output planetary. I am Butch/56sedandelivery.

 

My dads53 Olds 88 was parked in reverse. One time the engine stalled while backing up and the rear wheels just locked up while the car was still moving. With no engine in reverse the trans locked.

 

Use cast iron Power glide seal rings instead the ends lock together they seal better and are easyer to install. Used to be the trick in the day.

 

Thanks, I'll have to look into that for my next Hydro project.

 

So I have another problem. Topped off fluid while idling. I get no response between any gears. Just a slight lurch forward around 1000 Rpms. No change between any gears. Neutral -slight lurch forward. Reverse - slight lurch forward. What the heck!!!?

 

With engine off. Trans fluid Level about 1/2 inch above full mark. Running it takes it down to full mark. So oil pump is working? Took 11.5 qts

 

I don't know anything about these.

I did look in a 57 Chiltons for a diagnosis. Closest problem they showed was "no drive in any gear" Way too many things they said to check, and some were with trans removed.

You asked about pump working. Look at this quote: "The rear band is spring applied and hydraulically released. This is why if you turn the driven torus when in any range other than R, the tail shaft will turn."

From what I guess on that quote, is that the trans output/(and)driveshaft, could not turn, unless there is oil pressure to release rear band spring?? Can the car be pushed while idling in N ? Would that say there is pressure, or does it have more than one pump?

Or wait for D2 or somebody else

 

What I was trying to test, is whatever "takes the trans out of park" when the motor starts up.

From what little I know, put in R then shut off engine, then that is "park".

So, if you can manually move the car with motor running, does that help somebody diagnose it a bit deeper?

 

57 is a slightly different trans. This one doesn't have a park position. If you put it in reverse and roll forward a prawl falls down preventing this from happening. But I can't even get it to do that. IOf course that part worked fine till I put it in the car and added fluid. Regardless of the gear it does the same thing. Wheels of the ground and high rpm tires rotate forward. At idle you can rotate tires in either direction

 

So "parking prawl will not catch if there is oil pressure or if the car is in anything but reverse. "Since I cannot get it to catch even with engine off and with shifter in reverse position with the engine off I'm fairly certain it is stuck in neutral.

 

Check your manual valve for proper adjustment. The parking pawl engages by the manual lever in the R position. Like you said, if in neutral nothing happens, just like the manual valve stuck in N. Pull the side cover and re-attach the outside lever. Then move and see what is happening. That should give you a clear picture of the problem.

 

When I pulled off side cover Piston was stuck preventing parking prawl from coming down. That was one problem. D2 has been helping me troubleshoot this thing. Been through all the easy stuff. Talked to another guy and he said there is a tiny key that must be perfectly in place on the shaft to turn the pump. Not mentioned in any oldsmobile manuals but is in the Pontiac. I can't really remember the key so I hope that is the problem because I am in the process of pulling the trans as we speak. If the keyway is there then anyone want a 54 olds for cheap. Haha