powerglide rolling forward when applying transbrake
 

I just went to the track this past weekend, the transmission had no passes on it at all and when i applied the transbrake it rolled forward. The band adjustment is fine and the line pressure is good. Does anyone have any idea what could be causing it. I know i can run the line lock with the transbrake but i would like to stay away from doing that. thanks alot, nate

Several things can cause it, you say the band is correct where is it set ?

What is your line pressure? Should be around 200 psi. Band servo should be a dual ring for best operation. Pressure leak somewhere will cause it, solenoid valve not aligned properly. What type VB, pro tree, standard or double dump?

The band adjustment is 3 1/2 turns out. pressure is around 220, i have a tci dual ring servo, with a tci pro tree brake. Thanks for the replies, nate

3 1/2 is a tad tight for me but not your issue. Drop the pan and make sure the solenoid pushes the valve in all the way.

What he said

If it rolls forward with the brake set, the reverse clutch isn't applying. If it rolls back, it's a band issue. Could be as simple as a brake solenoid failure or wrong plunger, or could be a cut seal on the reverse piston. Does it go into reverse? If reverse works, most likely a bad or wrong solenoid.....

I dropped the pan and the solenoid does push the valve in all the way. Also the car does go into reverse. Would the roll stop from tci be an option that could fix it? thanks for all the advice so far. Nate

Does the transbrake set after rolling forward a little, or does it not set at all?

Just as Johnracer said, What is your reverse clutch pack clearance? What RPM do you stage at? Your band adjustment is fine, Reverse is not applying fast enough.