THM400 3 speed tranny reverse jerk
 

Hi Guys, not sure if im at the correct forum, but the vehicle i have is a rolls royce silver shadow which uses the 3speed THM400 from GM, which was widely used in cadillacs in the 70s. I am unable to find a solution in the rolls royce forums hence im here =/

The tranny shifts up and down just fine, and engages into Drive smoothly.
However, everytime i shift into reverse, there is a heavy jerk throughout the whole vehicle. My mountings are good hence we can rule that out. The engine RPM is around 700, so its quite alright. Engaging forward gears all are ok. Can i confirm that the tranny is blown? Or are there any other possible sources of adjustment?

Appreciate any advice! Thanks!

Reverse uses the Direct clutch, (also used for 3rd gear) and the low-reverse band. The band is not used for low gear in the "D" position, only when low gear is manually selected.

If manual low is similarly harsh, I'd suspect a broken ac***ulator spring for the reverse band. Been a long time since I've been inside a 400.


EDIT: Oh, for fukk sakes, this site has software that won't allow me to spell a transmission part because the letters C U M are used.