YJ: AX-15 shifting issue after rebuild - What did I screw up? - Great Lakes 4x4. The largest offroad forum in the Midwest

manicjester3 · April 16th, 2012, 10:28 AM

When I bought my YJ, the transmission (transmission 1) was completely toasted, all synchros were bad, so I swapped in another AX-15 (transmission 2) that I had from a previous project. The input bearing on transmission 2 went bad, but was still mildly derivable for short distances, so I bought a rebuild kit and rebuilt transmission 1. This was my first manual transmission rebuild, but I have disassembled a few before and I understand how everything works and goes together. Everything went fine when I rebuilt transmission 1, but when I shift into first gear from a stop, it grinds like crazy. If I put it in first, keep some force on it and slowly let the clutch out, it eventually catches the gear and will go just fine. Also, if I downshift into first while moving, it will be just fine and not grind at all. To me, it seems like the 1-2 shift collar is not fully engaging the dog teeth on the first cluster gear. It goes in and out of all the other gears and downshifts into first gear like it was bran new though. It is not a clutch issue or a synchronizer because if I do not press the clutch, it will not go into gear or grind or anything, so the synchro is doing its job.

Someone who knows more about manual transmission troubleshooting/rebuilding: did I possibly do something wrong during assembly, is my first cluster gear bad, or is there something else I may be overlooking?

I have a feeling it is my first cluster gear that is bad, but I do not want to pay another $200+ for the gear, thrust washer and bearing. I gave the second transmission to a friend of mine who wants to rebuild it for a project of his, so I probably won't be able to use the gear out of that transmission. Any help will be very appreciated. Thanks, Alex

April 16th, 2012, 10:28 AM	#1
manicjester3 Senior Member Join Date: 08-15-08 Location: Brighton, MI Posts: 260 iTrader: (7)	AX-15 shifting issue after rebuild - What did I screw up? When I bought my YJ, the transmission (transmission 1) was completely toasted, all synchros were bad, so I swapped in another AX-15 (transmission 2) that I had from a previous project. The input bearing on transmission 2 went bad, but was still mildly derivable for short distances, so I bought a rebuild kit and rebuilt transmission 1. This was my first manual transmission rebuild, but I have disassembled a few before and I understand how everything works and goes together. Everything went fine when I rebuilt transmission 1, but when I shift into first gear from a stop, it grinds like crazy. If I put it in first, keep some force on it and slowly let the clutch out, it eventually catches the gear and will go just fine. Also, if I downshift into first while moving, it will be just fine and not grind at all. To me, it seems like the 1-2 shift collar is not fully engaging the dog teeth on the first cluster gear. It goes in and out of all the other gears and downshifts into first gear like it was bran new though. It is not a clutch issue or a synchronizer because if I do not press the clutch, it will not go into gear or grind or anything, so the synchro is doing its job. Someone who knows more about manual transmission troubleshooting/rebuilding: did I possibly do something wrong during assembly, is my first cluster gear bad, or is there something else I may be overlooking? I have a feeling it is my first cluster gear that is bad, but I do not want to pay another $200+ for the gear, thrust washer and bearing. I gave the second transmission to a friend of mine who wants to rebuild it for a project of his, so I probably won't be able to use the gear out of that transmission. Any help will be very appreciated. Thanks, Alex __________________ Jeeps don't break things, their schedule for upgrading weak parts just gets a new time scale on occasion.