350 (Super) Turbo-Hydramatic Failure and Rebuild
 

Brief history, I had a low reverse roller clutch assembly literally explode and destroy the case. I continued to manually shift the truck until I could gather the tools, literature, and parts necessary to properly rebuild and upgrade a 350 Turbo. Thanks to Clinebarger and his willingness to share his knowledge he walked me through a rebuild on another 350THM that was swapped out for the tranny that blew. That transmission is still pulling strong as the rebuild went off without a hitch and I must say I gained a lot of confidence in my wrenching skills as well as much respect for Clinebarger for walking me through my first transmission rebuild. Now the case on the original 350THM eaten up pretty well when that low reverse clutch fragmented. No big deal because I went ahead and installed one of these, http://www.ebay.com/itm/TH350-TH350C...d%3D8075007548 with the wide Borg and Warner roller clutch, hardened sprag race, duel fed the directs, along with a couple other upgrades that escape my memory at the moment. I was installing the pump when I realized the pump screw bosses were warn out to the point that one had split (cracked) rendering the case useless, (scrap!)
I was given a "Unicase" and simply transferred the internals to the Unicase and installed the tranny into my mildly built big block truck which brings us up to current and the reason I started this thread.
The "Super Turbo" only had 1st and 2nd and no 3rd gear at all! :eek: So out comes the tranny to troubleshoot my rebuild and find out where I went wrong. It was immediately evident once I pulled the pan that the 1-2 valve assembly retaining pin had dropped out due to an apparent sticking valve assembly. :dohh: Heres the pic, https://scontent-dft4-2.xx.fbcdn.net...24&oe=598E9C5F Question; Would the 1-2 valve affect the 2-3 shift? I ask this because although soft, It did shift from 1st to 2nd just no 3rd? Another factor that may or may not have come into play is the governor. I modified the weights and springs in the governor to increase the shift rpm at WOT. I'm wondering if that may have something to do with no 3rd gear situation? I'm in the process of dismantling rechecking my rebuild and specs, I will keep you updated, heres the trick governor modeled after the BBC Super Sport and Corvette governors of the era. https://scontent-dft4-2.xx.fbcdn.net...08&oe=598892E9 Although the worn appearance this governor's lands checked good at .800"...Thanks, ~Ghostrider~

Re: 350 (Super) Turbo-Hydramatic Failure and Rebuild
 

The bushing coming out will cause a massive line pressure leak & cause soft shifts.

Re: 350 (Super) Turbo-Hydramatic Failure and Rebuild
 

I would suggest to take the rest of the TH 350 a part since you have it out and inspect it. Most likely your direct clutches could be burnt a bit....

make sure you replace the bushing in the direct drum with a wider one, that area of this trans seems to be a high troubled area... this trans likes its bushings replaced, always replace the bushings in this transmission.