no reverse turbo 400

[Jay Wicks]

fresh turbo 400 with hipsters brake, all forward gears ok, but no reverse. Reverse band is anchored ok, servo inspected, seals checked, check ball in place. Trans was air tested at main line pressure port with selector valve in reverse. hipster and trans guys are baffled. Any ideas what to look at next???

 

[jakeshoe]

Too short servo pin.

 

[EightSecV6]

fresh turbo 400 with hipsters brake, all forward gears ok, but no reverse. Reverse band is anchored ok, servo inspected, seals checked, check ball in place. Trans was air tested at main line pressure port with selector valve in reverse. hipster and trans guys are baffled. Any ideas what to look at next???

Did you try putting it in reverse and pressing the transbrake button?

 

[Jay Wicks]

Yep, tried putting it in reverse, reverse with brake engaged, and neutral with brake engaged, sorta tugs at the car like it wants to back up but won't, no reverse. Also, I believe due to this problem, the trans brake does not hold at all in 1st gear. Clunks in nice from neutral to first, all forward gears are solid and shift firm. I'll check the length on the servo pin. Did GM make more than one length??

 

[jakeshoe]

Yep,
You have a too short pin..
7 different lengths from GM.
Buy the longest one and grind it to fit.