89 GW slips in Rev on hills and is weird

[Johnny]

PO of my 89 GW had a rebuilt trans about 15k ago. Now reverse is intermittent. Backing up and out of my steep driveway requires me to shift back to drive a few times to get it to go. When it won't go back and up the drive it will go forward if I'm not on the brakes. Funny thing is that when it won't go the motor doesn't race like its in neutral. It seems to be torquing on something but the car won't go back. I was told I may need pinion bearings soon in the rear and that had been making a bit of a whine. Anybody have an idea? Trans or rear axle or what? Help! And thanks.

[Bob Barry]

It could be as simple as a loose rear band in your tranny. If that drum is spinning, the engine will still be spinning stuff, but just not making it go backwards. In fact, I think it might try to make the truck go forward.

I don't think worn pinion bearings would do this, unless they were binding the teet of the pinion and ring-gear together, but to do that the pinion would be so bad that it would be undriveable.

[Johnny]

If it is a loose rear band on the trans does the trans have to be removed or can it be done in place.

[Bob Barry]

It can be done in-place; you do have to drop the transmission pan, at which point you may as well replace the filter and the fluid that comes out.