manual transmission ax15 shifting issue

[vwtipeii]

Hi gang,

My lil YJ is finally running strong but like always there are a few bugs I am still working out. The most annoying one is with the clutch and transmission. i had a new slave cylinder put on a few months ago. Now when the Jeep get's hot the clutch still has pedal but the transmission doesn't really want to shift into gear. it gets so bad that i have to shut the Jeep off and put the Jeep in gear. I just had Danny (freeway dan) bleed the clutch. It only does this when the Jeep gets warm. We even found some old exhaust wrap and wrapped the hydraulic line running to the clutch fluid reservoir.

Another possible contributing factor that I am working on is that the Jeep has a very high idle now with the new ECU. I am still trying to get that sorted out. With a very high idle everything is spinning very fast and the clutch has to work even harder so thit may be another contributing factor.

Have any of you ever had an issue like this with a manual Jeep?

Thanks,
B

[6spdYJ]

Brett,

How does the pedal feel? if it has very little resistance & the clutch grabs right off the floor, it could have an air bubble in the master cylinder. If the master is not bench-bled they can take a long time to work out. The other thing the masters like to do is leak fluid past the rear seal and down the firewall either in the engine compartment or under the dash. If fluid is leaking out, air is getting in. Look for traces of leakage under the master cylinder.
The other consideration is the condition of the synchros in the transmission. In my AX-15, the synchros were fine but one of the synchro keys had broken in half and the synchro ring was hit and miss to work properly.
Seeing that your exhaust isn't really near the hydraulic line, I kinda doubt the fluid is boiling - especially since the line is plastic. It would likely melt through if that was the case.
Another thing to check would be the push rod from the slave to the throwout arm. I have seen one of the plastic tips come loose and fall off while it was reassembled. This would limit disengagement. It's unlikely, but possible.

[jonah]

Does it act/feel normal when cold?

Does the clutch engage at the same point hot and cold?

My sm465 is the opposite, shifts terrible until it gets good and hot, then it just shifts slow. Is it just hard getting it into gear while sitting still or is it tough to shift through the gears? If it will run through the gears then you can assume the synchros are good on those gears, the first gear synchro could be bad but I would guess it is the clutch dragging. The high idle rpm could be magnifying the problem, how many rpm at idle? The motor hasn't come out of the jeep lately has it?

[vwtipeii]

lol... motor was out and rebuild last summer. i have only had it out twice since then. clutch engages at the same point more or less.... it just doesn't like to shift once it gets hot. Very annoying. First thigns first we are trying to bring down the idle.. the tac is off (of course) so I don't really know how high the idle is but it sounds like it is near 1500 or maybe more. IT shows 2200 on the tac.. but again that is not accurate.

[aw12345]

Does it act/feel normal when cold?

Does the clutch engage at the same point hot and cold?

My sm465 is the opposite, shifts terrible until it gets good and hot, then it just shifts slow. Is it just hard getting it into gear while sitting still or is it tough to shift through the gears? If it will run through the gears then you can assume the synchros are good on those gears, the first gear synchro could be bad but I would guess it is the clutch dragging. The high idle rpm could be magnifying the problem, how many rpm at idle? The motor hasn't come out of the jeep lately has it?

SM465 has no synchros on first and reverse hard shifting when cold means trans oil ius to thick when cold.
On Skeeters jalopy bring idle down to 600-800 rpm if it doesn't shift any better after pumping clutch pedal 10 times in a row then air in system is not an issue.. If there is lil to no freeplay on pedal then excessive wear of clutch pedal linkage and what not is not an issue either.
Look at a tight pilot bearing bushing, oil on the clutch or something in that direction, this crap started after the engine got rebuilt so if lowering the idle to a reasonable level doesn't work, start looking at how the clutch and related parts got installed

[jonah]

Yeah, on the 465 I switched to a little thinner oil and it helped cold shifting a bit. But no speed shifting on that gear box.

Ax15 has a synchro on first right? High idle and a tight pilot bushing could do it.

Bring it out to CB this weekend and we can look at it.

What tuning software are you using? Can you data log while you drive?

[6spdYJ]

Good points guys. The AX-15 is fully synchro'd. The pilot is a bearing in OEM form. When was the last fluid change? Also, does the shifter handle toss around while driving at highway speeds? If the pilot is worn it can allow the clutch disc to clamp ever so slightly off canter and cause all sorts of vibrations - and sometimes not.