I have a 90 yj, 5 speed. My synchronizers in the transmission blew. I had another trannny out of a 90 put in. It runs great during slower speeds and city driving, like 45 mph or less. However, twice when I was on the highway for about a half an hour or so the tranny stopped working. Both times I was getting off an exit ramp and as I pulled it out of 5th to go to 4th there was nothing there, In fact, I had no gears at all, just neutral. The clutch was in the entire way and I tried with all my force, but it still would not go into any gear. The next morning however, with a little force, the stick moved into gear and worked smoothly after that. I took the jeep back to the mechanic that put the tranny in and he said it was caused by air in the hydraulic clutch line. He explained that as the clutch is pressed in the fluid moves the clutch plates apart to allow the stick to move into gear, but the air pocket must have worked to the front and the clutch did not work because air doesn't open the plates like the fluid should. Anyway, this was after the first time it happened. The mechanic re-bled the lines 3 times he said, however it happened again the other night. I am now unsure of what the problem is, could there still be some air in the lines? A pin hole in a line? Or is there something else causing the transmission to temporarily fail? Has this happened to anyone else? Someone please help me! It only has 88,000 miles on the motor and I have invested almost $3,000 into a 5'' lift, 33'' tires, bumpers etc... However, if this problem is not resolved I will be forced to trade the jeep in for something else. After spending $700 for the tranny I cannot keep putting money into a vehicle that is not reliable. If anyone has knowledge about this please help me! Thanks, Dan

You mechanic is right....kinda. Your problem is in the Slave cylnder(hydrolic clutch). If you have re-bled 3 times then chances are you need to replace the slave cylnder. At this time its also a good idea (at least this is what we recomend at my shop) to replace the clutch and maybe have the fly wheel resurfaced. Anyways, the slave cylinder will cost you about $175 and about 5 hours worth of work to intall it.

Next time you replace a transmission, you should go ahead and reaplce the clutch and everything else...it will save you more hassles in the long run. Also, slave cylinders going out are a really common problem on all 1990- up Jeep transmissions (AX15,AX5). However once fixed, they are a good trans for a Jeep.