Clutch not fully disengaging.

[Dickinson County Comanche]

This is for my 1994 ZJ 5 speed, but it should apply to any external slave AX-15, I’d think. 
 

New clutch components in November. If it’s within the bellhousing (minus the flywheel) it’s been replaced. New master, slave, line, the works.

 

It has a Power Torque (from O’Reilly’s) slave and master (one from a B-150 Ram Van will work with the original rod and the mounting plate installed.

 

When it’s cold, the clutch seems normal, but when it gets to operating temperature, it doesn’t engage all the way so it drags the clutch when sitting in a gear or going into gear. I’ve tried 3 different clutch systems all to no avail (2nd one did improve a little bit with a slightly longer rod, but nevertheless was still doing the same thing)

 

At my wits end with this thing, to the point I’ve started looking for a decent XJ to replace it. 

[pizzaman09]

What's the condition of the soft lines?  Could they be swollen and not letting you get all the fluid you need to the slave?  Could your master cylinder be bad?  Possibly not returning all of the way?

[Dickinson County Comanche]

3 hours ago, pizzaman09 said:

What's the condition of the soft lines?  Could they be swollen and not letting you get all the fluid you need to the slave?  Could your master cylinder be bad?  Possibly not returning all of the way?

Master is new, the other 2 new ones I’ve put on did the same thing so I’m starting to think it’s not a clutch hydraulics problem. I almost think it might be that the flywheel is worn down. It does have 330k on it 

[pizzaman09]

I wonder if something else it worn out, like the fork.  

 

When you push the clutch in, does it disengage very low near the floor?

[cruiser54]

Another thought, the disc heats up and expands. 

 

I can't tell you how many times we put new clutches in and experienced this issue. 

It's an easy fix. 

 

Drive down the road in 4th gear at 35 MPH or so. Push the clutch in and rev the motor up. Slip the clutch about 10 times until you just start to smell it. Go park the truck and let everything cool down for a few hours. 

[Dickinson County Comanche]

On 6/24/2023 at 6:40 AM, pizzaman09 said:

I wonder if something else it worn out, like the fork.  

 

When you push the clutch in, does it disengage very low near the floor?

I’d hope not, everything within the bellhousing minus the flywheel is brand new, but yes, very low to the floor, and when hot it won’t disengage whatsoever, and will start grabbing enough to roll even with the petal still touching the carpet.

[cruiser54]

Yep. 

[Dickinson County Comanche]

2 hours ago, cruiser54 said:

Yep. 

I went ahead and got a new flywheel just in case, it’s a good thing to have, but I’ll try your tip when I go get it later tonight and we’ll see how it does tomorrow.

[gogmorgo]

You can still buy supposedly correct hydraulics on Rock Auto. Instead of making do with the wrong master cylinder. 

[Dickinson County Comanche]

41 minutes ago, gogmorgo said:

You can still buy supposedly correct hydraulics on Rock Auto. Instead of making do with the wrong master cylinder. 

I’ve bought 2 of them and neither fixed it. The master I have right now is the correct one, (size & stroke) just was designed for a B-150 van and is metal vs the ZJs factory plastic one. It’s using the original ZJ pushrod and adapter plate

[OldSch88L]

Did you bleed the system properly? On my external slave AX5 it took an eternity to get the air out and get a somewhat functional clutch. I'd say between 100 and 200 pumps of the slave at 45 degrees, by hand,the hose end pointing up, while laying under the truck. Extremely boring process. It's now functional, but I think I'll give it a last round for good measure.

 

[cruiser54]

So, was the clutch replaced at the same time as the hydraulics? 

If so, it could be a combination of issues. 

 

[Dickinson County Comanche]

7 hours ago, OldSch88L said:

Did you bleed the system properly? On my external slave AX5 it took an eternity to get the air out and get a somewhat functional clutch. I'd say between 100 and 200 pumps of the slave at 45 degrees, by hand,the hose end pointing up, while laying under the truck. Extremely boring process. It's now functional, but I think I'll give it a last round for good measure.

 

The two first ones were prebled. I know I still have a little bit of air in my line right now cause if I try to pump it the pedal goes soft and won’t disengage when cold, but other than that it works just the same as all the others.

[Dickinson County Comanche]

1 hour ago, cruiser54 said:

So, was the clutch replaced at the same time as the hydraulics? 

If so, it could be a combination of issues. 

 

The Clutch disk, pressure plate, release bearing, clutch fork, pivot ball, clutch master/slave and front bearing plate on the transmission were all replaced at the same time. Only thing not new in that bellhousing is the flywheel and hardware.

[TurboedMJ]

Throwout bearing maybe?

[cruiser54]

Before replacing anything else, try this.

 

Pump the clutch pedal about 50 times and then walk away for a half hour. come back and see how the pedal feels.

 

That said, and based on my experience, along with it getting harder to disengage the clutch with higher temps, perform the "slip, stink, park" method I outlined above. 

[gogmorgo]

For whatever it’s worth, my ZJ’s clutch has always needed the last 1/4” of pedal travel to disengage properly. It got better after bleeding, but it’s still not great and I had to do it again once. I’ve just done it by pulling the slave off and slowly pumping it manually 50 times or so. It doesn’t lose fluid but the level in the reservoir does drop slightly after the bleed so I guess it must be sucking air in somewhere. It’s not a lot and it’s been a couple years between bleeds.

I also once had someone push the pedal in while I watched to see or hear any sort of leak, and the slave bulges alarmingly as it goes through its stroke. I’ve been thinking I should order a replacement at some point but it’s never shipped from the same place as anything else I’ve bought off Rockauto so I haven’t bothered. But if those ones are no good then maybe I shouldn’t?

 

 

[Dickinson County Comanche]

11 hours ago, TurboedMJ said:

Throwout bearing maybe?

Throwout/release were both replaced at the same time.

[Dickinson County Comanche]

2 hours ago, gogmorgo said:

For whatever it’s worth, my ZJ’s clutch has always needed the last 1/4” of pedal travel to disengage properly. It got better after bleeding, but it’s still not great and I had to do it again once. I’ve just done it by pulling the slave off and slowly pumping it manually 50 times or so. It doesn’t lose fluid but the level in the reservoir does drop slightly after the bleed so I guess it must be sucking air in somewhere. It’s not a lot and it’s been a couple years between bleeds.

I also once had someone push the pedal in while I watched to see or hear any sort of leak, and the slave bulges alarmingly as it goes through its stroke. I’ve been thinking I should order a replacement at some point but it’s never shipped from the same place as anything else I’ve bought off Rockauto so I haven’t bothered. But if those ones are no good then maybe I shouldn’t?

 

 

I have no clue if the Rockauto ones are any good or not anymore. Idk what to think about this, but I know it shouldn’t be grabbing while it’s foot on the floor at worst and barely off the floor at best. Something ain’t right.

[Dickinson County Comanche]

I did the slip n sit procedure. I couldn’t smell it at all but I was really giving it my all and since it’s windy I don’t want to run the risk of it being smelly and simply not being able to smell it.

[Dickinson County Comanche]

I ran it until some smoke came out. I’ll let it sit and see but my guess is flywheel than anything. Ik the clutch is a bit swelled cause of heat but I don’t think it’s going to fix it. But we’ll just have to see, only time will tell.

[gogmorgo]

35 minutes ago, Dickinson County Comanche said:

I have no clue if the Rockauto ones are any good or not anymore. Idk what to think about this, but I know it shouldn’t be grabbing while it’s foot on the floor at worst and barely off the floor at best. Something ain’t right.

Until this thread I’d been assuming my PO had roasted the clutch off, he had 33’s on it with the stock 3.55 gears, but now you’ve got me wondering. I think he said he had everything clutch replaced about six years before I bought it. Possible he used some of the same parts you got. I wasn’t convince they looked original but I never check for branding.

[Dickinson County Comanche]

went back out today after letting everything cool off and it’s grabbing right off the floor still. Guess I’ll be pulling the transmission and putting the new flywheel and maybe a shim in as well.

[Dickinson County Comanche]

I pulled the transmission today. Flywheel didn’t seem too worn, clutch disk looked good still. Going to replace the flywheel and pressure plate and hope that fixes it all.

[Dickinson County Comanche]

After replacing everything again (flywheel, clutch disk, clutch cover, throwout bearing), the clutch is significantly easier to push and grabs about halfway or slightly above halfway up, which is much improved over the previous grab right off the floor or not disengaging whatsoever. & as an added bonus, it stays the same way whether it’s cold or warm. 
 

So needless to say I believe I’ve fixed it. Idk exactly what was the culprit, nothing was absolutely glaringly wrong with any of the removed parts, but evidently something was wrong. Oh well, I’m just happy to have a clutch that finally doesn’t kill my leg to push or one that doesn’t make reverse harder to get into than Fort Knox.