well this is the situation, my 435 pops out of third when i gear down from 4th and let the engine slow the jeep down. if i hold the shifter in third gear it will not happen but i can feel the shifter start to wonder towards neutral. any ideas on the problem? i have done a few searches and i can't find anyone with this problem in a 435, only a 420 and a few with a 465.

oh ya i just replaced the countershaft bearings, input and output bearing, 2th/3rd syncro assembly and 4th gear syncro.

ps the tranny was popping out of third before i replaced everything as well and the shifter is not hitting anything.

Mine does that to and my tranny is freshly rebuilt. I think it falls out around the point where you should be down shifting again.

I bet your shifting fork is worn ormissing the little teflon pads and not completely engaging the gears..

a NP435 that will slowly walk out of gear when under a load for several reasons. In my case it is caused by a worn low gear cluster. But the problem has many possible causes. Worn thrust washers or bearings are common causes, as well as shift fork pads being worn

Originally posted by bronco78
a NP435 that will slowly walk out of gear when under a load for several reasons. In my case it is caused by a worn low gear cluster. But the problem has many possible causes. Worn thrust washers or bearings are common causes, as well as shift fork pads being worn

What he said. You have something worn, 9 times out of ten. It will be the parts that cost the most, the gears.

Originally posted by redwilly
Mine does that to and my tranny is freshly rebuilt. I think it falls out around the point where you should be down shifting again.

I would suggest you find a new rebuilder, and if you did the job your self.. I'd fire yourself and still get a different mech.