Technical 55 olds transmission slip

I have an all orginal 55 olds super 88 rocket. I just replaced all external seals and gaskets on the transmission. Prior to the reseal the transmission worked fine. After the reseal and replacemdnt of fluid now the transmission slips when changing gears. It has a 3 speed hydramatic transmission. I used dextron 3 fluid to refil the transmission. My question is did I use the wrong fluid or should I add an aditive to rejunivate the seals to accomidate the thinner fluid. Any suggestions would be appreciated.

 

I would drain it down and get some type F fluid It is known to make shifts more aggressive ( which most people do not want )

 

55 Olds trans would be a Dual Range Hydramatic, which is a 4 speed.
When is it exactly slipping? One shift, all shifts?? You need to be more specific.
We use Dexron lll in all our vintage transmission rebuilds without issues. I wouldn't think that's the cause.
Bill

 

It is slipping at each gear change. 1st to second is the worst. Drives fine after it finds the gear. It is a three speed transmission.

 

• It should be a Hydramatic (4sp) that has no park position with a quadrant of N-D4-D3-L-R and a 12 bolt pan
  
• A Jetaway (4sp) is distinguished from a Hydra-matic (Standard and Dual Range) as it has a park position and either 15 bolt pan (1956-59) or 14 bolt pan (1960-64). https://www.charlietranny.com/GMearly.htm

 

I do not think that this is correct. Was the Hydramatic not introduced as a 4-speed?

 

I am including a picture of the gear indicator on the dash. The only things I done were change both pan gaskets and the shifter shaft seals. Refilled the transmission with dextron three and it started slipping when changing gears.

 

Every hydro from 1940 - 1955 is a 4 speed. Your '55 if started in Dr will shift 3 times. If started in Super, it will shift twice. If started in Lo, it starts in 2nd & won't shift. However, if started in Lo or Super & throttle held to floor, it will force shift to a higher gear.
The factory shop manual, which you can access at Old Car Manual Project, has a trouble shooting chart listing dozens of possible causes for your slippage.

 

Thanks for the suggestion of Old Car Manual Project. I will look that up. It has been suggested to use type F ATF because it is thicker, would it be worth trying that first? Since this started with an 8 quart fluid change it sounds like the fluid could be an issue. What are the thoughts on using an additive to help rejuvenate the internal seals? If so what additive is recommended?

 

If it started slipping with fresh fluid you will need to tear it down and inspect the internals, they are likely worn out. The old fluid had all of the clutch friction material floating around in it and was able to transfer the torque through the clutches adequately enough to drive the car. I mean you could try the type F but it's very improbable to fix a slip in every gear.

 

Are you sure you really filled the transmission, as in all the way to the Max. marker with the engine running, the rear end jacked up and shifting through the gears? All the automatics I had within my frineds and family that acted up after a fluid change and didn´t before were not filled correctly. I ´d try to drive it a couple of miles until everything is warm an filled , let the car idle and recheck the fluid level.
You also said you changed the shifter shaft seals, so I suppose you had to remove the shift linkage. Are you sure it was put back together so it doesn´t bind or not travel all the way?
Sorry , I can´t think of anything else that could be wrong at the moment... bad thing is, I tend to forget my own screwups so I keep doing them again and again

 

I would first suspect the throttle pressure linkage for proper adjustment.
Even though the throttle lever and shaft is splined, it is possible to put it back on in a different position than it was originally.
With the throttle rod removed from the trans, there should be free movement of the trans lever and spring tension in one direction.
Bill

 

You said you changed the linkage seals.
A flat rubber seal on the manual linkage and a small cork seal on the throttle shaft?
There should have been a tiny pin and flat washer in the throttle shaft, that you would have to remove to change the seal. Are they still there?
That tiny pin keeps the trans internal throttle shaft lever properly located on the throttle pressure valve.
Bill

 

Yes I replaced the flat seal and the o ring on the throttle shaft all washers and pins properly installed. No leaks . All linkages are properly alligned and connected and are working properly.

 

Thanks everyone for the insights and suggestions about my transmission issues. This is the first older automatic transmission I have worked on so any ideas or suggestions are welcome. Not wanting to pull the transmission and rebuild it if I can help it.

 

Those units weigh a ton, I'd try the type F fluid before doing anything else.

 

As for my previous post, I don't know what I was thinking when I posted it. Must have had a brain fart. Not correct. One thing I found out is fluid level not high enough to completely fill the torus ring. Are you using the proper procedure for checking the fluid level? Didn't these use Type A fluid? Type F was typically used in Ford transmissions.
Old men and memory are not on the same page sometimes.

 

I have experienced that same phenomenon when changing the fluid in older cars. Pocket Nick seems to have a point. Sometimes what seems like a good idea opens the proverbial can of worms. If you are sure that the throttle pressure linkage is properly adjusted and that the gear selector is putting the transmission solidly in each gear detent, then I would first verify that the fluid level is correct. Then maybe hook up a gauge and check the line pressure like the troubleshooting procedure says. If the pressure is too low nothing will work right. The old repair manuals show band adjustments at very frequent intervals compared to modern transmissions but if it was working fine before it’s hard to imagine that a fluid change would require a band adjustment. But, you never know.
As to using the Type F fluid, my long time transmission guy recommended it to tighten up the shifts in GM transmissions and I’ve used it for years with no ill effects. He also recommended Lucas transmission additive for transmissions that have sat unused for long periods as a first step to see if they will return to normal service. It has worked for me. He was using it long before they became a well known supplier. It might be worth a try before tearing it down for a rebuild if everything else has been done.

 

I have verified that all linkages are working properly. I have been reading about the Lucas Oil Transmission Fix product and think it might be worth a try. Should I replace the atf fluid to type F before I put in the additive or try the additive with the Dextron 3?

 

Dexron

 

I just talked to Lucas Oil tech support and they recommend using the Transmission Fix or Conditioner for this problem, but do not use their product with type F or CVT oils. I will try this and post an update.

 

If it is slipping, Type F fluid won't help. You need to fix the problem. While I have worked on a lot of automatic transmissions, I've not worked on the one you have. I just checked all my manuals and I don't have any on the early Hydramatic. I would suggest going online and seeing if you can pickup a 1955 Oldsmobile workshop manual. That would have everything you wanted to know about your transmission.

 

Just a 'dab' of topic but......will using Type F (or just a qt or two) HARM a 700 R/200R/4L-60 type GM transmission?
Is type F a good substitute for B & M Trick Shift?
Thanx,
6sally6

 

I would only use type F in transmissions without electric controls, modern fluids are like modern oil they are slicker.

 

Back in the 70's when I taught automatic transmission rebuild, we replaced a lot of type A with type F to give more positive shifts. On today's transmissions I would not use anything but the manufacturer's recommended fluid.

 

I did a little research for you this afternoon. Could not find your problem in any troubleshooting info I have but try this : To follow the proper fluid level check after a fluid change on your transmission run the engine at high idle for 1 1/2 minutes then run at slow idle with the transmission in neutral and check the level. The reasoning is to make sure the converter is totally full before checking. Fluid capacity after a change should require 8 to 10 quarts. Also, the throttle linkage on these is a critical adjustment. It determines the shift point and kickdown. The shift rod adjustment is pretty straight forward. The easiest way to check this by putting the shift lever in gear and with the linkage disconnected at the trans and check to make sure the trans lever is in the detent and not between or up the ramp to an adjoining one. Adjust as needed so the rod will connect to the lever without interference. Do this in each gear to make sure they all fall into their proper detent. Some cars require the engine to be raised in order to remove the pan. That can upset the linkage settings. Good luck to you. I had a couple of '55 Olds and I loved them.

 

Well I am glad to report the transmission slip is fixed. Turns out that the kick down leaver does more than just put the transmission into passing gear. It also controls shift points. I had removed the original carburator and installed an Elderbrock which required a complete redesign of the linkage. My new linkage only moved the kick down lever whenI approached full throttle. Passing gear worked perfectly with the new setup. I was talking to David at Autotran.us about my shifting problem and he said the he thought the kick down linkage also control shift points so with that in mind I analized the original carb and linkage and modified my linkage to reproduce the same movement relationship between the throttle snd kick down. Test drive after modification produced amazing results. No slippage or banging into gears. She drives like she's a teenager again. Thanks to everyone thst made suggestions and comments. If you ever need transmission parts for these older cars David at Autotran.us may be able to help you. He is a great source fo parts an knowledge.

 

Glad to hear you got the linkage correct. I had done a swap years ago and modified the linkage lever ratio to match up to the throttle lever of the hydramatic. Worked great.

 

It might have been nice to mention that in your first post. Instead you said ". The only things I done were change both pan gaskets and the shifter shaft seals. Refilled the transmission with dextron three and it started slipping when changing gears." Glad you got it figured out though.