Okay, this is a post on my brother-in-law's truck so I do not have first hand experience on this problem.

He has a 1991 Dodge Ram 4 X 4 with a 360 engine and OD transmission. He claims that his pickup will not go into reverse. It will not back up at all. BUT, he says that if you put it in 4WD then it will back up but it seems to slip a little. My immediate guess is just that the transmission needs a rebuild, but since he is cheap, he will not agree to that.

He wants me to do the rebuild if it needs to be done. I have never touched a Dodge transmission nor have I touched an overdrive. I have taken apart and rebuilt a GM Powerglide and a GM TH350. I would be willing to maybe take on the task if I could find some good step by step books and some good advice. But, before I go that far, I would like to know if there is maybe a bad sensor that could be causing this or not? I also have read that there is a servo pack inside these transmissions that sometimes get plugged causing shifting issues as well. Could this be the problem?

It seems like no one knows much about transmissions, so I am looking for all the help I can get. Hopefully there are some true "gearheads" in this forum that can help me out some.

Thanks!

 

Wish I could help but unfortunately I haven't touched the tranny in my truck. When it grenaded itself I took it to a shop to get it fixed. Seems like one of those things you just want done right, and in the driveway isn't the place for the job.
Plus I've got a 727, so it's a different tranny anyway.

 

I don't know much about the transmissions from '91... But the front axle is vacuum actuated, which kinda makes me wonder if the transmission has a vacuum actuation that is being affected by a bad line or something. It's the only thing I can think of to check that would cause the 4wd to have any affect on the transmission... It's a start at least.

 

heh. My front axle used to be vacuum. But it wasn't working well so I got rid of it and put in the 4x4posi-lok cable instead. The vacuum lines run to the top of the transfer case and then to a vacuum canister, then to the front axle. Since mine's completely disconnected (plugged everywhere) I doubt that it has any effect on the tranny itself.

How's the fluid look? My gut feeling is that it needs to be serviced at the very least. Drop the tranny pan and take a look. Undoubtedly there's something that needs adjustment or replacement.