My brothers car makes a LARGE lunging bang when I shift into reverse. Any ideas. I checked the engine mounts and transmision mounts which were all good. Fluid level is good. Nothing out of the norm when shifting into forward. Everything else is fine except shifting into reverse. I'm puzzled?

check the u joints. dr. ed

89 is a front wheel drive if I'm not mistaken. You better look into a set of CV joints.

If it is fine in all other gears and shifts well then it sounds like a sticking accumulator or valve in the transmission. CV joints should clunk both ways. Might want a trans shop to look at it before it does more damage. Might want to avoid A ll A utomatics M ust C ome O ut though....

take it straight to the junkyard

Had a front wheel drive cutlass at one time that did the same thing.
The thunk is from a sticking shift valve inside the transmission. You can get some special lube for those valves, add it to the tranny, drive a bit and it should clear up. If they are really bad, the tranny will have to come apart to fix them.

actually there are three valves in the tranny that can cause this ,you need to drop the front end out to get to the tranny to do this ,which is worth more money and time than the car books out depending on the mileage and shape. but each valve is 100.00 and you need to replace all three,the tranny treatment worked long enough to park the car and sell for 400.00 AS IS!