1955 Transmission Question

[Jeff Rosansky CLC #28373]

Yes, another Hydromatic question. Looking for advice on the best course of action. First of all, a little backstory. Car sitting about 20 years brought back to life this year. I had several people tell me on posts and pm's to change the fluid, not change the fluid, change just the case and not the taurus, drive it and it will tell me when it is time to change, etc. Bottom line is that I did not change it-- I know this is controversial. I have no experience with transmissions in general but especially these early ones. It up shifts and downshifts well and I have not made any adjustments at all to anything. It does however leak quite badly out the front so at some point I will need to pull it but I was waiting until winter as I am sick of the summer heat. When we top it off we are using Dexmerc as it says it is compatability with Dexteron III. We have about 1300 miles on her now and have put a fair amount of new fluid in it. The drips in the pan are more red now than in the past but still darker than new.
It is just starting to shudder when coming to a stop and downshifting into 1st. The 1-2 shift is also a bit harsher. Not bad but a little harsher than 2-3 (which has always been good but I read this is the harshest of all the shifts.
All gears feel solid.  No slipping and all the shifts are good and solid with no delays.
Is the Dexmerc the wrong fluid and starting to show? I am wondering if the new fluid is washing things off in there and the filter is starting to plug up. I think she is telling me it is time for a fluid change. Should I change just the main body and not the taurus? Is Dexmerc the wrong stuff? Again, all operating normally and if the 1st drives were like this then I probably wouldn't do anything. However we are starting to notice a change, albeit slight and want to get ahrad of it before we hurt anything. More prominent when cold than hot.
Appreciate any tips and advice. 
Jeff

[walt chomosh #23510]

Jeff,
  My 1955CDV had sat for 18yrs when I found it.I changed the trans fluid and added "transX",then, ran it for a season or less before doing it again,adding "transX" the second time. Since then,almost 20yrs later, I've changed the fluid a couple of times or so and add the product that is supposed to be a "whale oil" replacement. I've wanted to take the trans to Irby Westmoreland in Forth Worth for a "kit". (I tow a 1955 Airstream Travel Trailer) Problem is, as a retired mechanic I have a problem with trying to fix something that isn't broke! (I've tried many,many times to fix something that's not broke and simply can't do it!).....walt....tulsa,ok

[Bob Kielar]

Hello Jeff,
                 When I had the engine and transmission out of my 55 some five years ago (man time flies) I changed the fluid in both the taurus and the transmission. I used Dexmerc and it shifts fine after tweaking the t.v. rod. and idle. I don’t believe there is a filter in the trans like a more modern car has. If you need a taurus gasket or other transmission parts Fatsco is the place to go to.

Keep Cruzin,

Bob Kielar

[Jeff Rosansky CLC #28373]

Thanks guys. It looks like there is some sort of screen. I just presumed it was a filter. If it runs and shifts as it does now I will be happy I just don't want to do any damage to anything. As I want to pull it later this year/beginning of next I didn't know if I should change the fluid or not because I will have to change it again when I drop it. I just didn't know how these fail and want to be as sure as I can that this isn't the start of something.
Jeff

[Bizzteacher]

Wanted to take a shot to see if anyone in this thread is familiar or could give advice on this...

I have a 55 Series 62 that I am restoring and the transmission was rebuilt by a transmission shop that obviously did not know what they were doing. Long story short, the car barely creeps in first gear and will go in reverse but nothing else.
Ive since had the governor replaced and the bands adjusted but still no luck.

I was told by someone that it sounds like a "check ball"?? but have no idea what that is (If it even is something)?.

Any ideas or suggestions; or anyone with a working transmission (55 only).

Thanks,

Hugh
480 241-5849

[walt chomosh #23510]

Hugh,
  There is a you tube vid by a technical school transmission instructor that's really good. He does a teardown and reassembly of a hydro. Possibly his vid could help you.....walt...tulsa,ok 

[savemy67]

Hello Jeff (if you are still following your original post) and Hugh,

The video to which Walt refers is by Professor John Kelly of Weber State University, Utah (see link below).  He has a curriculum vitae that includes so many automotive certifications that it is as big as a tablecloth.

His videos on the Hydra-Matic are very instructive (watch all five).  As I recall, he uses a 1952 Hydra-Matic in his videos.  The '52 is essentially the same as the '55.

One of the concerns when using a modern fluid - even though backwardly compatible - is the interaction of the fresh fluid with the composition paper friction plates that may be decades old.  There is a possibility that performance may not be as when both fluid and plates were original.  Another issue is that rubber seals deteriorate.  This can result in pressure loss leading to symptoms like shudder.

If Jeff's transmission has never been rebuilt, the symptoms may indicate a need to do so, at which time new plates and new fluid should perform satisfactorily.  The attached photo shows the "filter" from a '47 Hydra-Matic.  I believe the '55 is similar.  It is a fine mesh screen made of brass/copper.  If serviced, it should be cleaned thoroughly with a solvent like Brake Clean, and a soft brush.  Do not use a steel brush as the screen is relatively delicate.

Jeff, have you done any more with the transmission?  How bad was/is the leak?  If the leak is bad, the symptoms may be due to fluid loss.  Be sure to check the fluid level - on level ground - per the shop manual procedure.

If you are slowly increasing the proportion of newer fluid, and the symptoms persist, a complete change may have a different effect - one that will tell you whether or not it is time for a rebuild.

The torus gets its name from the Latin word for the shape (like a doughnut) of the "cushion" used at the bottom of classical Greek columns.

https://www.youtube.com/watch?v=ygkRuwCpKxU&t=640s

Respectfully submitted,

Christopher Winter

[Jeff Rosansky CLC #28373]

Hello Jeff (if you are still following your original post.

Hello,
Yep,.I'm still here.
We've actually done nothing. It still drips but we just keep the fluid topped off. Slight shutter when shifting  down to 1st when hot.
Thanks