I have an 02 supercrew fx4. I have not had any problems with the transmission but 2 days ago after driving about 30 miles it would shift into reverse but wouldn't go any were like it was setting there slipping. It would drive forward just fine. I have not drove the truck in a few days went out there everything worked just fine reverse worked great. Drove about 10 miles stopped tried reverse nothing. I am wondering what may be causing this? What would fix it or does the tranny need to be rebuilt or a new one?

Thanks

 

A rebuild would fix it. I suspect the reverse clutch seal has failed. When the fluid is cold it is thicker and the seal can hold it. When the fluid thins as it gets warmer the seal leaks the pressure that should be applying the clutch.