Greetings:

I have posted this frustrating question in the past (as have others) but have never seen anyone post a solution if it wasn't caused by a bad tranny mount, dirty fluid or mis-adjusted linkage. I thought I'd give it another shot in case anyone has anything to share.

I have a '91 740 B230F with the AW70L transmission. When it gets hot (like after at least a 20-minute highway run or if it has been driven for several hours) the transmission will slip and shudder when in reverse. It is especially noticable if I have to back uphill. It will do this regardless of whether it is summer or winter. Reverse is fine when the transmission is cooler - like just driving on short trips.

The transmission mount was replaced and the linkage is adjusted properly. The driveshaft support and bearing are new. The motor mounts have been replaced and are OK. The cooler lines are clear and the radiator is new. Cooler line flushes have had no affect. The control cable is adjusted properly. The transmission was also rebuilt about 40,000 miles ago when the previous owner had the car.

I am stumped - has anyone had this problem and solved it there where it wasn't any of the causes that I mentioned above?

Thanks in advance,

Andrew S.