Maxwell Chace

A couple months ago I posted a thread about my grinding synchros and such in my '95, which I addressed with some Redline MT90. Not a perfect fix, but it behaves much better. However I have a further inquiry.

Often times when downshifting, or just upshifting in general, my gearbox will not allow me to shift into a certain gear. It acts as if the slot for the stick to fit into that gear doesn't exist, and no matter how much force is used, it is impossible to put the stick into that gear. Most often, this is 2nd Gear, where I am just blocked from entering the gear. However, if I put the stick in first, and while still holding the clutch, shift into second. It usually will then go in. This is very confusing to me and was wondering if anyone knew what the deal was with gears being locked out and randomly unable to be shifted into. Clutch, slave cylinder? Thanks in advance for responses.

PatHenry

Worn synchros or worn shift collars in the transmission or possibly damage to the gear teeth. Difficulty shifting into 2nd is common with the AX15.

On a side note - when I was shopping for my 00 TJ the sales guy at the stealership claimed that they went to the NV3550 because people kept burning out 2nd gear. I think it was a cost or weight issue.. the AX15 was used for almost a decade across multiple vehicles and IMO is a MUCH more durable tranny than the NV3550. My dad put 400k on one that ran perfect when the Jeep was towed away. I blew an internal bearing on the NV3550 after 302k and numerous prior issues.

A problem with your clutch or slave cylinder would present itself as a problem in all gears equally and likely all the time. You probably would not be able to get the Jeep moving in the first place.

Do NOT force the tranny into gear. If you are having difficulty getting the Jeep into gear, you need to try to better align the engine speed with the gear. (In other words, more/less gas after you push the clutch in to compensate for the high internal parts wear.)

4.3L XJ

Before you get into the tranny, check that clutch. If it doesn't release properly, it can give you the same symptoms. To check it, at a dead stop try to shift into reverse. If it grinds the gears or won't let you shift, it is the clutch not releasing all the way that does it.