Is the hydraulic clutch adjustable?

Hey ... I have a '91 Jeep Cherokee with hydraulic clutch ... slave cylinder is in the middle of the AX15 tranny bell housing with the shaft poking out through the middle of the slave cylinder.

When I push the clutch pedal all the way to the floor, the clutch won't fully disengage.

I've bled the clutch thoroughly ... it's bled ... no air in the system at all. And it's not leaking at all either. Clutch fluid reservoir is completely full after being untouched for more than a year.

Here's some more information:
- When it's cold, it seems to disengage better. After it heats up, it disengages less.
- I'm sure the clutch isn't fully disengaged, because when I put it in gear, the jeep sometimes jumps forward a little (barely noticeable) -- and that's with the clutch pedal on the floor.
- I put in a new clutch and slave cylinder last year when I put in a new motor. The problem started about 4 months after installation.
- At the time of clutch replacement, I took the flywheel in to have it refaced. Is it possible they took too much off the flywheel? Maybe it will be necessary to put shims underneath the base of the slave cylinder?

- Is it possible to adjust the clutch? Perhaps a connecting rod between the pedal and the clutch master cylinder could be lengthened?

Any help would be much appreciated.

Thanks!!

Too much taken off the flywheel - no. When the flywheel gets resurfaced, they do the entire face of the flywheel. The mounting surface for the pressure plate stays the same as the clutch friction surface.

What brand(s) of parts did you use when you replaced the slave and the and the master cylinders? Some are pretty crappy and quit working fairly quickly.

Have you had to add any fluid since you noticed the symptoms?

Did you "bench bleed" both the master and slave cylinders before you installed them? you may have an air bubble at the top of the slave in the tranny that you can't get rid of.

Another rare occurrence is bulging of the plastic fluid line - if yours has it. Some were aluminum, but those plastic lines can get soft with the heat of the exhaust manifold (it's just a few inches from the manifold). If it's bulged, it could be "ballooning" when you push in on the clutch. Be sure to check the entire length of this line.

YELLAHEEP said:

Too much taken off the flywheel - no. When the flywheel gets resurfaced, they do the entire face of the flywheel. The mounting surface for the pressure plate stays the same as the clutch friction surface.

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Hi ... thanks for the response ... I'll check your other suggestions, but I wanted to reply to your flywheel comment.

I was thinking the same thing you were thinking, but after a while, I realized: If you resurface the flywheel, it will move the entire clutch assembly (friction plate and pressure plate) further away from the internal slave cylinder, which sits unmoving in the tranny bell housing. Therefore, the slave cylinder throw-out bearing will have to move further forward to fully depress the springs of the pressure plate and disengage the clutch. Make sense? If you take too much off the flywheel, it can be too far away from the slave cylinder, which will make it impossible to fully depress the pressure plate springs, and disengage the clutch.

After I did the clutch job, I read that you aren't supposed to have the flywheel refaced, because the "tolerances are too close."

I think a solution to this might be to put a shim under the base of the slave cylinder to move it closer to the new face of the flywheel ... thus "compensating" for the increased distance.

Seems to me that if the tollerances are that close, there's a design flaw there. I can't imagine that .030 shaved off would cause the problems you're having. If more than that was removed, then the place that did the resurfacing should be recommending replacement instead of resurfacing.

Your shim idea might work, but it sucks that you gotta drop the trans to do the simple shim.

YELLAHEEP said:

Seems to me that if the tollerances are that close, there's a design flaw there. I can't imagine that .030 shaved off would cause the problems you're having. If more than that was removed, then the place that did the resurfacing should be recommending replacement instead of resurfacing.

Your shim idea might work, but it sucks that you gotta drop the trans to do the simple shim.

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Yella ... I want to thank you for taking the time to respond ... you were the only one ...

I agree ... internal slave cylinder is a really retarded design -- both because of the "tolerances" issue, and for the fact that you have to drop the tranny to do any slave cylinder service. I think jeep has switched away from that ... but I could be wrong.

The flywheel had some pretty deep grooves in it, and I told the machine shop to take as much as they needed to make the surface smooth, which was my mistake. I didn't really think it through how it would affect the relative position with the cylinder. I would guess they took as much as .100 or even more.

I'll try to see if I can add a little length to the connecting rod between clutch pedal and master cylinder. That might do the trick. If not, I'll have to drop the tranny and shim the slave cylinder with some sheet metal.

As for dropping the tranny, I'm going to have to do that sometime anyway, because it makes a deep vibration at high speeds ... I *think* it's the tranny doing that, but again, I'm not sure yet. Need to do some more research on that. I'll try replacing all the CV joints first to see if that corrects the problem. But the tranny has 200K on it, and is probably due for a rebuild.

Rear Dif has broken teeth on the spider gear, so I'll probably get that rebuilt at the same time.

I'm babying this jeep ... fixing it up to keep it forever, so I'm gradually bringing everything into "as new" condition. Making mistakes, though, so it's kind of 2 steps forward, 1 step back.

Thanks again for your help.

From experience, resurfacing the flywheel will cause the pedal to disengage much further down the throw. Yes the tolerances are that tight. That is why DC says to not resurface the flywheel.

Getting a good bleed is the most important thing. You said it worked for a while. That says that the amount you took off was not excessive. That means that you either have a master cylinder getting leaky or you need to bleed the system. My bet is on a MC that is getting leaky. This is a common problem.

The only way I have found to get a good bleed on a clutch is to use an electric vacuum bleeder. The hand held ones don't cut it. If you end up replacing the master cylinder, I recommend going with a Howes racing MC that is slightly larger than the stock bore. That will move your pedal up. Actually I posted how to do it about a year ago. You end up doing some very basic modifications, but you end up with a rebuildable, adjustable, stainless steel bore master cylinder.

Resurfacing the flywheel is a big no no.

However...as it worked for 4 months and seems to work when cold, I suggest you check the master, then slave. One of the 2 could very well be shot. Last time I had a clutch failure it was as you described....worked fine when cold....not at all when hot....it was the master. Easy to check....when hot, open the bleeder, put your finger over it, and have someone press the pedal...if the master worjs ynp whll .ht be aBne to h~dd the F`uid in
Rev

old_man said:

If you end up replacing the master cylinder, I recommend going with a Howes racing MC that is slightly larger than the stock bore. That will move your pedal up. Actually I posted how to do it about a year ago. You end up doing some very basic modifications, but you end up with a rebuildable, adjustable, stainless steel bore master cylinder.

Click to expand...

Hi Old_Man ... thanks for the advice. Can you tell me which adapter you used to attach the oem fluid lines to the Howes MC?

Also ... I just checked the OEM MC's listed on various websites. They all have a bore of 11/16" (0.685") to 17.75 mm (0.70") to 23/32" (0.72").

Are you sure you used the 0.875" MC from Howes? It seems that a 0.75" will also give some extra bore. I'm just trying to make sure I don't over-do it.

Thanks!!

And ... last question .... do you have the Howe Part number?

Thanks!!

Just to add fuel.....

My OEM master from vatozone had a lifetime warrenty....when it failed....I just took it abck and got a new one. The one I replaced lasted 75K or so.

Rev

Look here: http://store.summitracing.com/egnsearch.asp?Ntt=howe&N=700+115+4294852250&Ntk=KeywordSearch

montanaman said:

As for dropping the tranny, I'm going to have to do that sometime anyway, because it makes a deep vibration at high speeds ... I *think* it's the tranny doing that, but again, I'm not sure yet. Need to do some more research on that.

Click to expand...

Hey i just wanted to say that vibration might just be your front driveshaft, my xj starts vibrating about 75 mph but it doesn't when i take out the front driveshaft. it's a 4 speed auto.

also, i have an '88 comanche with the same clutch problem, internal slave that won't work just right. i think this is a pretty common problem. i had the clutch system disconnected for something and havent' ever been able to get all the bubbles out. seems like it's just a bleeding problem, and not failure, but i'm not sure yet.

anywho, just wanted to let you know about the driveshaft thing so you can test if that's vibrating instead of rebuilding your tranny.

You do realize this thread is over a year old?

Rev