Hi All,

I noticed a leak coming from my speedometer housing (transmission side) and from my research there is a bullet shaped housing that holds the speedo gear. I understand that there are two seals (one O-Ring outside, and one inside to seal the plastic gear).

Two questions:

1. Is it a slam dunk as to which seals to buy for the TH-350 in my car or do I have to haul the bullet out first? I notice there are different types?
2. I can't seem to find the O Ring for the outside of the housing. Anyone have a link (rockauto would be great) or other? I hear it may be the same O Ring as the 700R4 but not sure.

 

Take the speedo housing with you to your nearest transmission shop. Chances are they will have a bunch of them. Transmission gasket kits include the speedo seals, if the transmission they are building is out of a 4wd truck those seals aren’t needed. The inner seal (the one that seals between the speedo gear and housing) is the same on all the GM Rwd transmissions. The seal between the trans case and speedo housing is dependent on what size housing you have. There is a small metal clip that holds the inner seal in place. On problem speedo housings it sometimes help to put two seals inside. I’ll never understand how a rubber seal can cut a groove in a metal part.

 

awesome, thanks for the feedback man, i'll do just that there are a couple near my place

 

My local O'Reilly's had the seal for less than $1. The part number I got directly off the seal was 1240382. I have an oring hoard from working on aircraft for decades.
Maybe your local auto parts will have that and the o-ring.
Rockauto would have been much more with shipping- and they had a 5 seal minimum (stupid).

 

5 seals! that'll last me 200 years since this one was original! i'm planning on hauling the bullet out and bringing it with me. I'm pretty excited to not have to use oven cleaner on my garage floor to clean up transmission fluid