I have a 79 20R w/4 speed tranny. It pops out of reverse, I bought it this way. Does anyone know how to fix this or does it require a rebuild?

 

mine would pop out of first gear...i took a look under one day while i was changing the oil...turns out the reason why is becausesome of the T-case bolts were loose...and some of the tranny bolts were loose...so i took a socket set and tightened every bolt i could find everywhere on the truck..turns out alot of them were loose...so check all that...it sure helped mine

 

theres a shifter bushing that wears out that will cause it to pop out of gear I bought one from wab fab it helped mine but I think my syncro is going out on my first gear I have just got used to holding the shifter when in first gear.

the bushing is a lot cheaper to start with compared to rebuilding the tranny.

 

Can you hold it in reverse or does it push your hand out.

 

Thanks all. Yes I can hold it reverse. It doesn't feel like the gears are meshing completly. Like there riding on the edge of each other.

 

Make sure the shifter is not binding on the shift boots.

 

IIRC, if you can hold it in reverse, the shift bushing is at fault. At least do that before rebuilding, as others have mentioned.

 

Thanks will try the bushing and also the seat on the shifter lever. There are aftermarket heavy duty ones here.
http://www.marlincrawler.com/htm/transmission/1a.htm

 

Yep, marlin is the way to go. I installed their shifter seat and bushing when I put in my clutch. One of the best mods you can do for the price.