TJ clutch question

[DarinM]

Good day.
I have an '04 Rubicon. My clutch quit working a few days ago. No slippage - it just wouldn't let me shift into gear out of neutral while idling and it was grabbing while upshifting and driving. I also had screeching sounds when the clutch was depressed while in gear and stopped. My assumption was that the throwout bearing might be bad - but I understand this to be an uncommon thing to go out on its own.

I'm out of my league to work on this kind of stuff, so I had a mechanic that I believe to be honest take a look at it. He felt the master/slave assembly (one piece unit on these) should be the first thing to replace and did so.

Here's my question - I understand these to be "self-adjusting." After he did the install he said it was working much better than what I had, but was still grabbing a bit. He said it wouldn't go into reverse while idling and was still screeching a bit. He ordered another master/slave assembly in case the one he installed was bad - which is to arrive at his shop tomorrow (Tuesday). This was Saturday. My Jeep is my DD, so I went ahead and picked it up as I don't have a plan B for wheels and it is drivable as is. I drove a bit Sunday and then to work and back today. As of my drive home tonight, my clutch seems to be working perfectly normally (as far as a Jeep clutch can get to normal). I don't know how the "self-adjusting" works and if my clutch is fixed or if it's just waiting for me to get out to BFE when it will quit working again. But it has definitely improved in feel and function each time I've driven since I picked it up.

Any words of wisdom? I thank you in advance.

 

[Hill Bill E.]

Sounds like it had some air in the system, and by using the clutch, it worked it's way out.


And they are two pieces, the Master cylinder (clutch peddle activates this) and the 'Slave cylinder' (this pushes the throw out bearing against the pressure plate)


Some Slaves are 'internal', meaning they are inside the bell housing, and some are 'external' meaning they ar mounted on the outside of the bell housing.


The problem was probably the slave cylinder, when they go bad and leak, the fluid runs out of the master cylinder, nd it feels like the clutch is slowly going out.


If it's working OK now, I would just check the level of fluid in the clutch master (next to the brake master cylinder) and keep an eye on the fluid.

 

[DarinM]

Thanks. On the TJs the part comes as a single sealed unit with master and slave cylinder, and thankfully is external so to replace it you don't have to pull the drivetrain apart. Costs alot less.
Appreciate the input, and what you said is pretty much what I've been thinking (and hoping).
I'll report back in the next couple of days and hopefully will be a happy Jeep guy.

 

[goodtimes]

The clutch master cylinder is what is mounted on your firewall, right next to the brake master cylinder (brake = clear/white reservoir, clutch = all black and smaller than the brake master). The clutch slave cylinder is mounted on the side of the transmission, and is connected to the clutch master cylinder by a hydraulic line. These are separate components -- at least they used to be. I should know -- I moved one of the production lines from the mid-west to the west coast about 8 years ago . . .

*edit -- did the one that was installed come pre-assembled (master + line + slave)? Seems like it would be a tough way to install it . . .

 

[alexfm]

Sounds like it had some air in the system, and by using the clutch, it worked it's way out.


And they are two pieces, the Master cylinder (clutch peddle activates this) and the 'Slave cylinder' (this pushes the throw out bearing against the pressure plate)


Some Slaves are 'internal', meaning they are inside the bell housing, and some are 'external' meaning they ar mounted on the outside of the bell housing.


The problem was probably the slave cylinder, when they go bad and leak, the fluid runs out of the master cylinder, nd it feels like the clutch is slowly going out.


If it's working OK now, I would just check the level of fluid in the clutch master (next to the brake master cylinder) and keep an eye on the fluid.

Thats the same problem I've got with my XJ. My slave cylinder has a leak, and every couple weeks, it feels like the clutch is going out. I just check on the fluid when that starts to happen, and just top it off and keep motoring along.:bike_rider:

 

[DarinM]

The part does come pre-assembled, but I guess you might take it apart to install. Hardly seems like an efficient way to do things, but what do I know?

This morning it worked OK some of the time and didn't work so well at others. Is it possible that the hydraulic system on this new part isn't functioning properly? The clutch itself will either engage/disengage every time or it won't, right? I think that I'm getting inconsistent hydraulic pressure. I don't know what else could cause it to work fine one time and not work at all next.

Again, this is supposed to be self-adjusting - whatever that means. I've pumped the crap out of it. I do not think that has helped, although my left leg is now quite manly and muscled. Matches my right arm... hehehe

Thanks for your comments. Have a nice day.

 

[goodtimes]

It's self adjusting in the same way that your disk brakes are self adjusting.

Obviously, something isn't right -- I'd start with a leak check, followd by bleeding the system.

BTW, google says that you can buy the master and slave cylinders as separate components.

 

[Desert Dan]

If it was screeching with the clutch in it is probably the throwout bearing.
Sometimes a throw out bear can last quite a while even when making noise.
Does the sound go away with the clutch out?

How many miles on the Jeep?
If the hydraulics have been fixed then start saving for a whole new clutch and throwout bearing.

 

[DarinM]

If it was screeching with the clutch in it is probably the throwout bearing.
Sometimes a throw out bear can last quite a while even when making noise.
Does the sound go away with the clutch out?

Yes - I have no weird noises when the clutch is out. Only sometimes screeching when the clutch is in.

How many miles on the Jeep?
If the hydraulics have been fixed then start saving for a whole new clutch and throwout bearing.

I've got about 97,000 miles on it. Since I had this hydraulic assembly installed, it is working much, much better than it was. It was barely drivable prior to having this stuff done. Right now it's about 90% working and that's what is confusing me. I don't know if throwout bearings work OK some times and don't work at others.

Thanks again for y'alls' assistance. @Brian - I noticed the parts are available as separate units. I wonder how you know which one would need replacing?

 

[goodtimes]

@Brian - I noticed the parts are available as separate units. I wonder how you know which one would need replacing?

Both of them are essentially little single acting, spring return, hydraulic cylinders. As such, they only have fluid on one side of the piston. If you are getting fluid to the dry side of the cylinder -- the seals are bad and you need to replace it.

The system basically works like this: pushing the clutch pedal down moves a bunch of levers and rods which in turn moves the master cylinder piston from the dry end of the cylinder, towards the wet end of the cylinder. Assuming your seals are good, this forces fluid out of the cylinder. The line directs this fluid to the wet end of the slave cylinder, where it causes the slave cylinder piston to move from the wet end towards the dry end of the slave cylinder -- pushing on a series of levers and rods which disengages your clutch.

Hydraulic fluid is not compressible. Air is. So, if you have air in the system, it will compress, and your clutch won't work properly (on a related note -- have you ever drive a car that had a 'spongy' feel in the brake pedal? That's caused by air in the system).

Air can either be entrained in the fluid (lots of tiny bubbles mixed throughout the fluid), or it can be collected at one point (one big air bubble). The result will be the same -- and it doesn't matter where the bubble(s) are, the result is all the same. Its best to bleed the whole thing, running enough fresh fluid through the system to replace all of the old fluid. Google will point you to plenty of tutorials on how to bleed the clutch.

 

[goodtimes]

Oh, throw out bearings typically only complain while you have the clutch pedal pushed down -- with the clutch out (either neutral or in gear), the throw out bearing is essentially just sitting there, disconnected from everything.

Pilot bearings on the other hand, typically complain when engaging the clutch (not fully engaged, or fully disengaged). At least that is my experience with GM trucks of yore . . .

 

[DarinM]

Thanks, Brian.
We'll see about getting everything bled and see how that works.
If I can get all this done without spending a ton more money, I'll be out that way in about a month!

 

[goodtimes]

Bleeding the clutch is a pretty simple task. Traditionally it takes 2 people, but with one of the cheap brake bleeding kits out there (less than $10), you should be able to do it yourself, in your driveway, in about 15 minutes.

 

[DarinM]

Follow up -
The pilot bushing was in pieces when they dropped my transmission. The input shaft was gouged badly due to this.
So not only am I getting a new clutch, but I'm also getting some transmission repairs.
Expensive. But I guess I can expect to not experience further problems in this area for the foreseeable future.
I don't think I have abused the Jeep, although it has been driven a bit hard at times. Shortly before this failure, I did play some in some mud on a backroad near Austin. I don't recall doing anything evil to it, but maybe nearing 100k miles, recent addition of bigger tires, 2 adults, 2 kids in the Jeep - maybe all of this contributed to the demise. I don't know. I do know I won't be playing in any mud again.