When I was on the highway, my transmission started getting rather difficult to shift in my 4.0L, 5 speed (AX-15) Wrangler. By the end of the trip (approx 50mi), I could not shift at all unless I turned the engine off first (thus limiting me to 1st, 2nd, or rev). I limped it back home to find out from some very knowledgeable friends that it was the synchronizers in the transmission. These line up the engine & trans, thus allowing smooth shifting. These copper synchros wear/break excessively due to larger tires (I have 33"s with 4.88 gears), especially at higher speeds (whoops!). There are some aftermarket shift kits that have TITANIUM synchros. With these, the once vulnerable AX-15 trans is now quite bullet proof, although I wouldn't suggest trying!
When I was on the highway, my transmission started getting rather difficult to shift in my 4.0L, 5 speed (AX-15) Wrangler. By the end of the trip (approx 50mi), I could not shift at all unless I turned the engine off first (thus limiting me to 1st, 2nd, or rev). I limped it back home to find out from some very knowledgeable friends that it was the synchronizers in the transmission. These line up the engine & trans, thus allowing smooth shifting. These copper synchros wear/break excessively due to larger tires (I have 33"s with 4.88 gears), especially at higher speeds (whoops!). There are some aftermarket shift kits that have TITANIUM synchros. With these, the once vulnerable AX-15 trans is now quite bullet proof, although I wouldn't suggest trying!
- Jon C., Indian Head, MD, US