Dana 18 slips into neutral

When going downhill my Dana 18 will slip into neutral on a long downgrade. Only in high range and coasting with the weight of the vehicle pushing. Never pops out under load in forward or reverse. I just rebuilt it, all bearings and gears were really nice. I didn't really look too closely at the detent notches on the shift rails though. Would shimming the detent spring help, as it really shifts very lightly? Other than this, the t case is really quiet and works well. Any ideas?

 

I put in a different detent spring and shimmed it about 1/8". It seems to shift firmly now. I'll post how well it works when I drive it tomorrow.

 

I have the same problem with mine after rebuilding it. I was thinking about shimming the spring. Just wondering if this would work. Keep us informed.

 

The detent springs can relax their tension over time. Try shimming them first as that's easy. If that doesn't work then something like worn gears, too much transmission endplay, etc. is most likely the cause.

 

Funny my Dana 20 would sometimes do that when just driving. Never could figure out what it was; fixed it self I think. I will look into it when I tear it down.

 

The shimming worked. Just tried it, worked perfect.