Got the car registered on Friday, wasn't able to take it for a real test drive until yesterday and ran into a little transmission problem. The first shift, i'm thinking its 2nd to 3rd, is fine, very firm no slipping, however i can take it right up to 55-60 with no more shifts, it doesn't even try. When i first drove the car a month or two ago before it was all the way put together the 2-3 shift was hesitant and i had to kind of wind it out and let off the throttle, then it would shift. i adjusted the rod between the carb and trans to what the manual stated and that shift became much better. Reading the manual last night, it looks like the valve body might have some crud in it. anyone ever remove one of these for cleaning? Anything else i should look into? i know the proper thing to do is a rebuild considering the seals are most likely dried up but if i could get through this summer with a "band aid" that would be fantastic. I did some google searches, there is an old timer trick where you add lacquer thinner to the oil and it help break up any varnish and apparently helps "condition" the seals. Not so sure about that one. I don't really think its Band related since they both should be released for fourth gear.

Out of the four transmissions i have, the one that had the cleanest oil is the one i chose to take a chance on, i did the Fatsco external seal kit, changed the fluid with Dexron 3, the fluid level is perfect and still looks brand new, which i guess it should considering there's only about 20 miles on it.

 

I don't know if I would try this. ATF already has a ton of detergents in it. Instead of using lacquer thinner it would probably be better to use an ATF additive. If it gives you peace of mind.

If you suspect crud in the valve body you can always drain the transmission, disassemble and clean the valve body & then reassemble everything with fresh ATF.

 

I have no knowledge of the history of your car (from this thread, at least).

(1) How long did this car sit without the transmission being placed into gear while under load e.g. driven for an extended (>100 miles) period of time?
(2) Was there transmission fluid in the transmission during the entire period the transmission was not being used?
(3) Depending on the condition of the transmission you currently installed & whether that transmission has or has not been used under load for a long, long time - a 20 mile drive down the road is unlikely sufficient mileage for a run-through (you're basically breaking in this transmission after sitting how long?)
(4) The fact you have clean fluid is an excellent sign. It should look brand new after only 20 miles; but,

I'd run the transmission through its paces for several more extended highway runs - five or six 20 mile runs cycling the fluid so it heats up during driving and completely cools down before its next drive. Review the shifting at that time. Then, as Jesse suggested, consider cleaning the valve body. Just my 0.02

 

The transmission in question came from one of my parts cars, the last tag was from 1980, so its been sitting unused for 43 years, it was however full of fluid in both the torus and the transmission itself. The transmission that was originally in the car (the one i am currently driving) the fluid was almost sludge like, as a matter of fact, a lot of it is gunked up on the fins of the torus, that car sat in a barn from 1965 until 1992, then sat in a garage until 2019 when i acquired it. The other 2 transmissions that were part of the deal had fluid but were real nasty, no burnt smell but just really dirty.

What you suggested makes sense, some heat cycles may do it some good, maybe in the meantime i can remove the valve body out of one of the other transmissions, clean it and do a swap after some careful cleaning.

Since this is the first time driving the car, what is a safe speed to take it in what i guess would be "S" on the gear indicator? I took it up to 55 and didn't seem like the engine was spinning too fast but at the same time, the engine has only had a 20 minute cam break in and the 20 mile test run.

Thanks for the input fellas, very much appreciated. I'm hoping by mid week i can play around with it a bit more.

 

You might consider putting the rear on some jack stands and doing it in your garage.

 

Seals/Valves with likely voids of condensation/air/sludge sitting 40+ years beckons to be thoroughly bathed in fresh ATF with half dozen heat/cold cycles then another transmission flush. I’m certain you won’t see fresh clean ATF after several runs and heat/cold cycles. I’d run it at 45 mph extended. You should do this FIRST before you clean the valve body.

 

guess that's a good enough excuse to put some miles on. Once the rain stops I'll get driving, I will check back in later this week with results.

 

Haven't had a lot of time to get out and drive, ive done about 25-30 miles still without 4th gear.

Just an observation, i can start out in "LO" and it will stay there, i haven't pushed it to a forced upshift, but if i move the selector from "LO" to "S", nothing happens, it won't do the next upshift until i move the selector to "DR"
I have the afternoon off today so i'll put some more miles on the trans.

 

You should feel 4 different shifts, one to second is sometimes so smooth and quick it isn't noticed, second to third is usually the hard shift and forth is another smooth shift. Have you tried to adjust the carb to trans rod, sometime a little does a lot... Tedd

 

Did a little more playing around last night, It shifts at about 10mph, i'm thinking now it shifts from 1st gear and then directly to third, it is not a smooth shift at all, it is rather firm but doesn't really feel abnormal, i have played around with the linkage but it doesn't seem to do anything other than hold the shift to about 15mph then a really harsh into third. I have a Hydramatic manual waiting in the mailbox, not sure if it will have any more/less info than what is in the service manual but it was cheap enough so i'll give it a go.

 

I’ve had a good 10 hot/cold cycles and still no 4th gear, doesn’t even act like there is another gear to go. I took a valve body from one of my “spare” transmissions to see if there was any gunk inside of that one and for sure there was some minor sludge build up inside so I guess there is a chance the transmission currently on the car has a completely plugged passageway. The hydramatic manual states that the valve body can be soaked in gasoline (was very specific to not use carburetor cleaner) if a blockage is suspected so I may start there with my spare valve body, there are some great exploded diagrams of plungers/pistons/springs in the manual so I’m pretty confident I can get it back together and just swap it onto the transmission in the car, that’s my weekend goal at least.

 

Sounds like you might want to check the valve body for any debris and consider a rebuild for a long-term solution.

 

Have a look at this thread (below URL link) - some good information. Note the video contained in the thread >>>1955 Oldsmobile Hydra-Matic Rebuild in case you get that deep.
https://classicoldsmobile.com/forums...not-up-108615/

 

I did a complete disassembly of the spare valve body last night and there was quite a "sludge" build up inside, i cleaned all the parts up blew them dry and reassembled following the AMI Hydramatic manual i bought on Ebay, what i did notice upon reassembly is that the actuator plunger for where the carburetor linkage attached now has full contact for the whole stroke where it didn't before, so this may be what is happening with the valve body on the car now, may be acting like the throttle is wide open when it isn't. i really hope to get this done this weekend, if it doesn't change anything then i guess its time for a full rebuild. I did watch the youtube videos of disassembly and reassembly of the entire transmission, it looks pretty straight forward but its still something i don't think id like to attempt, some things are better left to the professionals.

 

 

The problem you are going to have is finding somebody who knows how to work on an old hydramatic. They are so old that there are few people left who worked on them in the day. When I had my 54, I had the transmission rebuilt in 2017 by a guy who was 78 at the time. He did an outstanding job but passed away a couple years ago. Fatsco might be able to give you a lead on a rebuilder. Good luck.

 

Cleaned out the valve body, long story short, still no fourth gear but the one shift it does do is silky smooth now but when it downshifts it is much more rough, also, when applying the throttle heavy above 30mph the transmission slips pretty bad so I guess now the bands are releasing but the clutches aren’t activating. The trouble shooting part of the manual doesn’t mention 1st, 3rd and reverse work but no 2 and 4 shift is due to a large internal leak, I didn’t see anything out of the ordinary but I may pull the pan this week and make sure the pick up at the filter is still together, I may even take a chance on one of the other transmissions since at the moment I have more time than money and other vehicles that need attention also. Thanks for the help everybody and if anything changes I’ll add to the chat.

 

Rear band is broken, hard to tell from this picture but my hands were too greasy to get a good picture, just to the right of that pipe at the top right, you can see some of the friction material, in the manual that’s where the band looks to be crimped. Guess no amount of driving would have helped this situation!! Thanks for all the help everybody, I really appreciate it.

 

Well, I’m happy to say that after taking a huge chance swapping transmissions that it actually worked out, the transmission that was attached to a 1954 engine I got as part of the deal when I bought my 98 works like a charm, what a pleasure to drive now, 3 distinct shifts, no slippage, it does leak out of the side cover but that’s my fault for trying to re-use an old gasket, new one will be here Saturday, going to put a few more miles on it, drain it to replace the side cover gasket and add some fresh fluid and hopefully that will be the end of the transmission chapter. In my previous post I incorrectly stated that the band was broken, that one was in fact fine, it wraps around the clutch drum differently than the rear clutch drum/band. I’m still going to disassemble to find out what the issue is with that one but for now it’s way more fun to actually drive the car.

 

Congrats. Persistence paid off for you. Be aware there is a slight difference in the 54 and 55 transmissions. The difference is in the tailshaft seal. They made a change in the 55 which was not an inprovement. You are much better off with the 54 transmission.

 

Not something I want to do again real soon, that’s for sure, the transmission removal, fantastic, very easy with minimal parts to be removed (when compared to a modern car) installing it was a whole different story, trying to get the input shaft, torus and transmission alignment pins all lined up, I used my lawnmower lift, the type that lifts up the front to get to the blades, oil changes etc, worked perfectly, raised it up and stayed perfectly level so if your ever in a pinch, go with the lawnmower lift!! I attached a picture of what the original transmission looked like inside when I removed the pan, it was untouched since at least 1965.