Quick TH400 Question..
 

I have located my tranny leak/leaks. Drivers side, either the front corner of pan or the the seal on the shift linkage. Really glad it wasn't the front seal. Wiped down the transmission and removed the inspection cover.
Been looking through my manuals and no reference if there is a "seal" or an "O" ring. on the shaft for the shifter.

Is it a seal or a O ring?

I plan on replacing the pan gasket and this seal or O ring.
thanks
Mark

It's a seal the size of a dime. Replacing the shift-shaft-seal is a very common repair.

Thanks SanDiego Paul...any ideas where to find one? Tried Advance and Auto Zone with no luck...will keep looking.

I had to visit my local tranny shop (a mom and pop one, not a chain).
They are usually included in the rebuild kit but the shop had some laying around.
Good luck!

If you drop the pan, you can remove shaft and replace the seal. Make sure you install it the right way.

The best deal is to get two seals and drive the first one in a little deeper and then put another right in on top of it. The bore is deep enough to hold both. It will help if the shaft is a little worn and will get seal on a new spot of shift shaft.

JIM

You need to look and make sure it uses a seal. Some of the early T-400 trans use a o-ring that fits into a groove that is cut in the shift shaft. Others use a seal that is pressed into the case into a recess around the shift shaft.
You can change the seal type without removing the shift shaft, If you can not dig it out with a pick, they make a tool that screws into the seal and pulls it out.
I just finished a rebuild on a 73 T-400 from a corvette that I am working on and it used the O-ring, not the seal. i rebuilt the T-400 in a 70 442 cutlass a while back and it used the seal, I am not sure what determines if it has one or the other except that I have seen them both ways over the years.
I have also rebuilt some T-350 trans and have seen them both ways .
The seal type is serviced at most local auto parts places if the counter man is smart enough to look it up.

Mark G

Thanks to everyone for their help!!! I did find the shaft seals online at Advance and Autozone....but not available in their stores.
I also have another issue with this tranny. The kickdown is not working....and I now am wondering if I should replace the solenoid while I have the pan off. But I am not sure where the problem is though.
Mark

I'd forgotten about the o ring type. I used to do a bunch of trans and they were fairly uncommon..at least to me.

Also correct on not having to pull shaft to change seal. I was just asleep on that one!

But putting two of them in there doesn't hurt a bit!


You can test solenoid by applying 12 volts to it to hear if clicks. Still no guarantee, but at least you'll know if it tries to work. I never saw many of them go bad...usually wire off or misadjusted switch.


JIM