Any 700R4 experts out there?

Tiny
ORIENTED331
  • MEMBER
  • 1970 GMC
Just rebuilt this 91 trans. When engine is started P, R & N work fine but nothing in D. If I put it in 3 it goes into forward and seems to work ok (wheels off the ground) but then it won't release the forward clutch until I shut the engine off. I replaced the entire valve body with a known good one and the same thing happens. Any ideas on what I screwed up?

Thanks!
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Tuesday, January 17th, 2006 AT 6:02 PM

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Tiny
MROVERDRIVE
  • MEMBER
:D Hi, i'm keith and I 've been rebuiding trannys for 29 years and probably done a couple thousand 700's. The way this tranny works is when you put it in OD the forward clutch comes on and the input sprag is holding. IN 3 the overrunig clutch comes on along with forward clutch. You did'nt say if it shifted thru the gears or not. The fact that it won't release the forward clutch unless you shut the engine off, did you change any hard parts in the input drum? There is a checball in the steel piston the alluminum forward piston sits in that should exhaust forward clutch oilout, somewhere there is ahole that, s letting oil in but not out. Is this unit an auxilary valve body trans? Wrong vb gaskets, or, did you put a check ball in the bathtub in the valvebody. Thats the forward clutch feed hole. Early 700, s used aball there but the axuilary units don, t. I, ve found that when a trans does something that odd or something that you don, t normally see, it, s either you put something in the wrong place or forgot somthing or you left something out. You, ve created a problem that, s not in any book. Your problem is never in the book. If I had a little more info about what you did to it would help. Putting a kit in is one thing, knowing if a piece is good or bad or knowing if it, s usable or not isthe hard part. When I rebuid a700 I replace allthe bushings, sprags, shift kits, band, . There, s alot more than just buying a kit with clutchs. Email me if you need some more info, thanks mroverdrive
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Sunday, January 22nd, 2006 AT 10:29 PM

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