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clutch heat fade??

S

stroked88

NAXJA Forum User
Location
Carlsbad NM
has anyone else had a similar problem? ive searched, but to no avail. I have an 88 that i have swapped in an ax15 from wrangler with internal slave. my exact problem is that after i have been driving in town for a while, when i stop with the transmission in neutral, and push the clutch in, i cannot get the transmission into gear. there is no grinding, but it feels like theres something there just stopping the shifter. If i turn the jeep off and put it in gear, it goes fine. I can start it in gear, or stop in gear with the clutch in and it doesnt try to jerk or lurch. this is whats got me confused. it shifts fine once im going, and if i put it in gear rolling it will go fine. but if im at a dead stop, it wont? when cold everything works well. all the hydraulic parts are for the 1988 and new. new centerforce clutch and pressure plate, rebuilt the ax15, and resurfaced the flywheel. did have a diff clutch in after rebuild and it worked fine but was replaced because it got noisy.
 
from what I've read, the resurfaced flywheel is the most likely culprit. The clutch slave doesn't have enough range of travel to compensate for the decreased thickness of the flywheel and causes the problems you describe.

My 2.5l/AX5 is showing the same symptoms without the resurfacing, but at 254,000 miles on the original clutch, I'm guessing it's just worn slam out in my case.
 
i would think it would do it all the time though?? also i did shim the slave outwards a little bit using some carrier bearing shims i had. probably about .010" it is still retained with the pin and one way slip on washer, but i had anticipated the slave problem.
 
I've convinced myself that it's just a case of "as things warm up, they expand at different rates" and there's not enough tolerance built into the system to accommodate the change.

I'll be interested to hear what solves the problem if you find the answer, but the usual "fix" for this ends up being 'replace everything from the flywheel to the clutch slave and the problem is gone.' It's enough of a PITA to change part by part to find out what was bad-- and I have to admit I'll be going that route when I do it too. I don't think 250,000+ miles is worth troubleshooting item by item on.
 
well i mean so far i HAVE replaced everything. in fact, this is the 2nd new clutch and pressure plate set. the last one was a RAM set up but i sent it back because the friction material had seperated from the hub and wouldnt let it disengage at all since it moved enough to stay in contact all the time. I have a theory that this is possibly an air pocket in the system somewhere, and when its cold, its small enough volume the clutch works ok. but as it warms, it expands and is too much for the master cylinder to compensatet for?? idk if that makes sense or not, ive tried gravity bleeding, traditional pump pump pump bleed, and opening the bleeder push pedal down close bleeder. but my friend let the resevoir run out so we had to bleed some more so there could still be air in the system.
 
can't refute the theory-- I'll definitely be checking for the solution! Please post up what you find and maybe I'll be able to stretch a few thousand miles out of mine if it's something other than too much clearance.

with two clutch sets doing the same thing, you're down to flywheel or the hydraulic system, I guess.
 
will do. could be the cheap-o autozone master cyl too:shocked:
 
stroked88 said:
well i mean so far i HAVE replaced everything. in fact, this is the 2nd new clutch and pressure plate set. the last one was a RAM set up but i sent it back because the friction material had seperated from the hub and wouldnt let it disengage at all since it moved enough to stay in contact all the time. I have a theory that this is possibly an air pocket in the system somewhere, and when its cold, its small enough volume the clutch works ok. but as it warms, it expands and is too much for the master cylinder to compensatet for?? idk if that makes sense or not, ive tried gravity bleeding, traditional pump pump pump bleed, and opening the bleeder push pedal down close bleeder. but my friend let the resevoir run out so we had to bleed some more so there could still be air in the system.
Click to expand...
Hold the slave piston in it's rest position with a clamp and then bleed it.
 
Which Centerforce? IIRC, mine was the Centerforce DF.

This is from a post of mine three years ago:

'I ignored the advice of a few here and went with the Centerforce, and had problems with the weights. When warm, they would not return from the 'deployed' position. It made it difficult to shift, almost impossible to engage first from a dead stop.
Always worked good starting out in the morning, only to piss me off down the road.'
 
Last edited:
its the centerforce2. thank you for that post! did you just remove the weights? or use a different pressure plate?
 
I installed the basic Luk clutch kit and it works great. I found out that Luk makes the OEM stuff and the disk that Centerforce sells too.
 
yeah, i noticed that it was a Luk also. i used a 7/8ths hole saw to drill an inspection hole in the bottom of the bellhousing today, and sprayed the fingers with brake cleaner while it was idling, and the lubricated the weights and fingers with dry moly spray lubricant. we'll see what happens
 
let me know what you find, mine's doing the same thing. i thought about bleeding it. i'd really like to convert it to cable, why the hell they'd bother with hydraulic is beyond me, it's always been a nightmare.
 
Vanimal said:
let me know what you find, mine's doing the same thing. i thought about bleeding it. i'd really like to convert it to cable, why the hell they'd bother with hydraulic is beyond me, it's always been a nightmare.
Click to expand...

? He cleaned and lubed the pressure plate, not the slave cylinder. The hydraulic slaves work fine.
 
what difference would haveing an external slave make? the hydraulic system is working fine, its the weights sticking on the centerforce pressure plate. ive always had good luck with the internal slaves. so what if you have to drop the trans to replace them? thats not very often, and you would still have to drop the trans to replace the throwout on an external?
 
ohh, and lubricating it helped, but still no dice. gonna see if i can have someone help me and push the clutch while i spray it so that maybe it will get the dry moly under the weights. :fingers crossed:
 
lubricating didnt work. swapped in another pressure plate i had. this one is a RAM. its made for a 350 chevy, but is dimensionally the same as a cherokee pressure plate. went for a drive, and it STILL does it. so its not the weights on the pressure plate sticking. its still heat related though.
 
Seems like I had the same problem with an 86. Had to bleed the clutch with the slave clamped in the "at rest" position.
 
how would i go about doing that with an internal slave?
 
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