[2000jack]

I have a Th400 that I had the shifter shaft seal changed last fall and it still leaks. Someone told me that it is possible the shaft could need replacing as it might to worn. Is the shaft replacement difficult and do you know where on the web I would find the procedure on replacing it. ?

 

[jakeshoe]

In the picture you can see the shaft, the "rooster comb" and the park linkage on the RH side of the case.

You have to remove the pump to replace the manual shaft unless you cut the nail that retains it and use a hitch pin to retain it. You loosen the nut that holds the rooster comb to the shaft, remove the nail, slide the shaft out. Replace the seal, install a new shaft (lubed and deburred), and then reattach everything. Pretty simple overall.

 

[2000jack]

Wow

I spent an hour trying to find this on the internet. Thanks a lot, Do you know where I could buy the shaft? I got a new seal from Auto zone.I tried looking in Auto Zone for the shaft on the internet, but I was overwhelmed by the parts list. I had gone to the Chevy dealership to get a new seal thinking perhaps the one I had originally gotten wasn't of the best quality. They had a picture of the transmission on the computer, but I do not remember if there was a part number. Anyway the parts guy spoke ("Oh yeah, this old stuff... haven't seen one of those in years... I don't know the books [diagrams] weren't that good then...no....Good luck!") like I was trying to find a top bow or something for a 1927 Chevy roadster. Must of been a part number because he did not have the seal anyway. Thanks again, Jack

 

[k-star]

leak

In Jakeshoe's post pay close attention to the part where he tells you to de-burr the shifter shaft. Look at the picture and notice the nut that holds the rooster comb on to the shaft. There is a rectangle flat on that shaft that fits into the comb. 99.9% of the time there will be a bad burr on the shaft right where the comb sits against it....After removing the pin i will remove the nut and only pull the shaft out enough to get the burr off then remove it the rest of the way... That burr will mark the case and also damage the new seal if it's not removed.

They also make a tool that removes the seal and installes the new one with-out removing the shaft... I have the tool but i have never needed to use it... So i cannot say for sure if there are any issues with it...


Keith

 

[jakeshoe]

Here's a pic of the seal tool:

I use it often.

I doubt GM services the TH400 stuff much anymore. If you know what interchanges from a 4L80E, you can get some parts for the TH400 at the dealer, but internal parts, good luck.

 

[jakeshoe]

Actually,
You seem to be in luck...

GM P/N 8679990 SHOULD be the shaft for a TH400. It's about $40 list price, quite a bit less shop price.

Double check the application when you go to the dealership, but I'm almost positive that's it.