Need advice from trans guy who really knows his stuff. Here's the background: 88gta, 5.7L w/vortec supercharger, b&m shift kit in 700r4 trans; LOST 3rd & 4th gear(3rd acts like nuetral).
Before commiting to pulling the trans & rebuild, my son & I decided to drop the valve body & check out anything that might relate to the B&M shift kit. (Yes, we'll replace with Transgo). We found the 3/4 accumulator piston lands (surfaces adjacent to piston seal) to be heavily scored & gouged. The piston bore (in the case) is also scuffed & scratched, but not as bad as the piston. The seal ring in the piston appears OK. The questions are:
1) Can the piston & bore condition cause enough seal leakage to cause loosing 3/4 gear? Presumably, insufficent pressure to apply the 3/4 clutch?
2) Reguardless, can the bore in the trans case be repaired & how? sleeve kit? hone & oversize piston?

We really need the above questions answered to decide how to procede.
Thanks, FJK

 

To make this short the transgo 2&3 reprogramming kit has you put a plug in the 3-4 accumulator feed hole. I would assume with this modification you could leave the piston out. I wouldn't but my point is that it's not used with the hole plugged so it's condition wouldn't matter.

 

As stated, you plug the feed hole to the accumulator (4th gear only) & reinstall the spring & piston with the seal. It basically does nothing after that. If the bore is tore up it will allow oil to leak away from the 3-4 clutch apply piston, there in turn helping to burn the clutches. It will help burn the 2-4 band also. By blocking the accumulator it will firm up 4th gear and help the 2-4 band to live longer, and at the same time you will not have to replace the case.