ZF-6 problem

Stroked550 · Sep 20, 2011

Not sure the best way to describe this but here it goes (assuming gears are labeled 1-6). 4th gear engagement is a bit off, like its not going in all the way, 5th is way off, and its impossible to get it in without grinding. Happened suddenly, truck popped out of 5th while under very light throttle and has been like this since. Any ideas?

Petro · Sep 20, 2011

synchronizer's ( spelling might be a little off ) maybe?

Betarocker · Sep 22, 2011

How old is the truck? My guess is the synchros.

Charles · Sep 22, 2011

I've had two of them do this after sustained heavy towing where they overheated. In my experience the ZF6 just can't take the heat.

Stroked550 · Sep 22, 2011

That is likely the problem then, truck regularly grosses 40k with the trailer on.

Charles · Sep 22, 2011

My 550 lost 4th gear recently. When I replace the trans I will be adding an automatic trans cooler up front. The one before this one did exactly as you describe above. Started popping out of 5th then 4th.

Jake · Sep 22, 2011

Neighbor s truck did this with third and the trans is trashed and he is having hell getting a quality reman

Petro · Sep 22, 2011

Charles said:
My 550 lost 4th gear recently. When I replace the trans I will be adding an automatic trans cooler up front. The one before this one did exactly as you describe above. Started popping out of 5th then 4th.

Make sure you make a thread on this, I would like to do the same thing and would like to see how you do it.