Need some help/suggestions; YJ won't go in gear

[DsmRacing]

Background: 95 YJ with 2.5L Manual AX5 Transmission, 231 Transfer Case

Swapped in a 98 AX5 Transmission and a brand new clutch. Torqued everything to factory specs, maybe a little over for good measure. Filled with fluids:
Np 231 ATF 4 Auto Trans fluid 1.75 qts or so
AX5 10W30 Mobile oil, approx 3.5 qts, but a lot did leak out on a level surface.

Buttoned it all back up, ran amazing for the test run, all gear shifted, smooth, able to downshift for a change. Ok, great, time to cleanup and head out. Got in again and noticed the smooth shifting was becoming rough. Took for a quick spin, brought it back and parked it. Came back and now I can't even get it into gear.

Here is what I have done so far:
pumped the crap out of the pedal; no change
swapped 98 slave cylinder in, no change
pumped clutch again, and even flushed the lines with new dot 3 fluid
tried pushing on the fork by hand, couldn't budge it ( good right)
checked transmission fluid, right at the top

The Jeep will not go into gear now when running. Off you can get into gear, kinda rough sounding.

Any suggestions? My buddy believes that somehow I have air in my lines, but the master and slave cylinder are unbleedable like traditional setups. There is pressure on the pedal with some play. I really don't want to pull the transmission again.

Thanks for any help and suggestions,

Chad

 

[RockChucker]

i am actually having this problem in my TJ as well, i have a 97 with an AX-15 out of a 98. i have had this problem for quite some time, but it has recently gotten worse. much worse actually. it will shift fine or go into gear fine as long as i'm moving, but as soon as i stop, it will not go into gear without turning the Jeep off.

Here is what I have done and learned/guessed about with my own observations and talking to people that know a lot more than me.

When it first started happening, I took it to J&G transmissions in murray. They jumped in the jeep and with in about 5 seconds said it was the slave or master cylinder. They told me since it is a sealed unit, i have to get a new one. so i did, hoping it would make things better. it didn't. as soon as the Jeep was up to operating temp, same thing. impossible to get into gear from a stop.

my next thought was, well maybe the synchros are going out, but the flaw in this reasoning is that it shifts fine when the vehicle isn't at operating temperature. i had recently picked up a new to me trans of ksl. i cracked the case, and everything checked out, the synchros and bearings were all good. i put it back together, and put it in the jeep. same thing. it shifted smoother, but still no going into gear from a stop.

i was talking to ben at teraflex plus about this, and we talked about the oil in the trans and everything, and then he had a thought. maybe it is the pilot bearing. it is creating enough friction on the input shaft b/c it is either too tight or not lubed enough, causing the input shaft to keep spinning, thus making it really hard to put into gear. this is where i'm at. i haven't had time or motivation to drop my trans again. but this makes sense in my mind.

when the jeep gets up to temp, the metals expand, and the pilot bearing expands, tightening its 'grip' on the input shaft. is it right? no idea, but that is where i'm at. my next step is to call the guys down at the six states clutch division and see if something like this is possible. i have had this problem, like i said, for quite some time, long before i did this clutch. it has just been worse. and both the clutches and pilot bearings i have gotten have been from them. we shall see. i'll post back after i talk to them.

also, where is your friction point on your clutch? is it right off the floor? if it is, that means you probably have a problem in your slave or master, or even your throw out bearing isn't moving enough. mine is a ways off the floor, yet another reason i have come to the conclusions i have...
good luck. hopefully this helps in some small way.

 

[I Lean]

I don't think it'd be the pilot bearing. It doesn't typically touch the input shaft, rather it slides on a "sleeve" outside the shaft. The sleeve is one piece with the input bearing retainer, the input shaft pokes through it. (on most trans' anyway....someone else will have to confirm/deny the AX15 is the same)

 

[DsmRacing]

The clutch engages right off the floor. I guess I'll look into a new master/slave. I did not replac the pilot bearing when indid the clutch. Could not get it out and the tool was too big. I hope that's not it. It did look ok though.

Thanks for some ideas.

 

[RockChucker]

carl-

when i did mine, i put in the pilot bearing, it rides right on the input shaft of the trans. there is a machined tip on the input shaft it rides on. the bearing has an outer cage, and needle bearings that ride on the shaft.

what do you suppose it could be?

edit: are you thinking of the throw out bearing? that doesn't touch the shaft, it does slide on a 'sleeve.' i'm talking the pilot bearing in the back of the crank.

 

[chans]

Rockchucker, did you try thicker gear lube? If it is only doing it when it is warm then the syncros might be getting worn and are spinning too fast. When its cold think of it like when you try to squirt the gear lube out of the bottle in winter time. It is super thick and when you drain the diff after driving around it is like water. So when it heats up and thinner the syncros have less drag. Try straight 90 wt. As to the original post, if it worked fine and all the sudden got bad and doesn't work at all it sounds like something worked loose or came off.

 

[I Lean]

carl-

when i did mine, i put in the pilot bearing, it rides right on the input shaft of the trans. there is a machined tip on the input shaft it rides on. the bearing has an outer cage, and needle bearings that ride on the shaft.

what do you suppose it could be?

edit: are you thinking of the throw out bearing? that doesn't touch the shaft, it does slide on a 'sleeve.' i'm talking the pilot bearing in the back of the crank.

Yep, throwout bearing was what I had in my brain, pilot bearing is what I typed.

Oops.

 

[DsmRacing]

Here's one more details. New master and slave Cylinder. Guess what, no fix!! Some I'm almost ready to pull the transmission. I'll let u know what I find!

Thanks again guys'

Chad

 

[RockChucker]

chans-

i actually had a 75 weight gear oil in it, and thought that was part of my problem. i looked up the spec on what oil it called for and it is 10w30 motor oil. that is what those japanese made trannies call for. so i changed, but still the same issues.

however, i stopped by the six states clutch shop today and talked to troy, and he even tried my jeep out. he is sure it is the pilot bearing. he was telling me that ever since manufacturers started moving towards needle bearings for a pilot, they have had nothing but problems. and he recommends brass. they didn't have one in stock but will make me one on monday. brass won't gall, and it is naturally lubricating, so that is why they work. and that is what they were for 60 years before they moved to a bearing. at least according to troy. anywho, that is where i'm at. i'll keep you posted.

dsm-
i'm kinda wondering if it could be your throwout or the pivot arm the throw out is on. i'm assuming you do have an external slave since you said it is a 98. maybe your throw out isn't able to travel enough? or maybe something did just work its way loose in the tranny.

when the clutch is in, do you have any noises? or is it quiet? noises could indicate a broken 'finger' on the pressure plate...i don't know what else to tell you man. hopefully you get it worked out.

 

[DsmRacing]

Final end to the Saga:

2 problems- pressure plate was not flush against the flywheel. I did not use any type of threadlock or double check my work, since it was close to 2 am when I finished this.

2nd issue: Decided I wanted a new clutch since there was a little damage from the throw out bearing. I have a lifetime warranty, might as well. Well, when i took the clutch back, we discovered that it was the wrong clutch!

Double checked my work, torqued everything correclty, correct clutch installed and now it shifts great!

useful info for someone:
to remove the pilot bearing, you need a blind hole puller set for the AX5 Transmission, $150 to rent, then return. For fluid, from the dealership, they use 10W30.... I used Mobile 1 10W30 non-synthetic.

Thanks guys' for all the suggestions.