clutch removal and replacement

[jonnywong]

Im trying to replace the clutch in my 95 XJ, I do have the haynes manual but im looking for some advice here as well. The first issue i have run into is trying to take off the pressure plate - it will rotate the whole flywheel when trying to loosen those bolts. I understand there is a special tool for holding the flywheel in place, but there are no stores open today and im wondering if there is a way around this. Also anything else i should know about doing the clutch would be helpful. Its for an AX15 tranny. thanks

 

[ChiXJeff]

Try having a buddy hold a socket at the harmonic balancer. Or wedge a long prybar between a couple of bolt heads. You'll have the same issue when you tighten them back up, by the way.

Check the condition of the pilot bearing/bushing. New flywheel?

 

[jonnywong]

well i got the pressure plate off with very few problems with just a ratchet and rubber mallet, although ill probably have more trouble putting it back on - might have to have someone at the harmonic balancer like you said. Looking at my clutch, flywheel and pressure plate im not sure if they are all really in need of replacement. Anyone got a link that shows what these worn components look like? I did a search couldn't find anything... Haynes manual has some pictures but there black and white not very good. might be able to post some pics of it here in a little bit

 

[scottmcneal]

Dude, all the time you spent, an you want to go cheap now? Always replace clutch, pressure plate, throw out bearing.. since your there i would also do the pilot shaft bearing.....Take the fly wheel in to have them check it...

 

[jonnywong]

right, it makes sense to replace everything. Im really trying to find out what is wrong with my XJ - i originally thought it was the tranny but i took it to the shop and they said nothing was wrong with it. Also tore apart the tcase and nothing. So im trying to figure out if my problem was in the clutch, and to be honest im not sure that it is although im not a real expert on these things.

What was happening was i would put in gear and let the clutch out, start to drive a little then all the sudden lots of grinding and no movement. no grinding in nuetral or when clutch was pressed in. This probably could be alot of different things but like i said tranny and tcase are good, not sure about the clutch. I would just like the reassurence of knowing what was wrong with it before i put it all back together.

 

[scottmcneal]

Does this happen when in 4 wheel drive to? Sounds like you lost gears to me..Try putting it in 2nd gear to start off.. I hate sticks...

 

[ChiXJeff]

The surface of the flywheel should be clean, smooth, and without any discoloration or cracks. The FSM claims the flywheel isn't resurfaceable.

Unfortunately, I don't think the shop is right. What you're describing really sounds like internal transmission issues, something like a bent shift fork. A bad clutch generally slips. If it's grinding, it should be really apparent once you get the trans split from the engine.

 

[alex22]

I just did a clutch kit in my jeep. There was nothing wrong with the clutch plate, the throw out bearing or the pressure plate. they all still had plenty of life left, But, the last owner saved himself 30 bucks by not replacing the throwout bearing. The clips that held the fork to the tranny shaft broke and the fork fell off and would grind against the pressure plate (fsm calls it the clutch housing). I had to drive it home with out a working clutch.

My entire clutch kit cost me $208 at my local NAPA. It included the new clutch plate, pressure plate, throw out bearing and pilot bearing. Now is not the time to cheap out on a few parts because it will come back to bite you later. I just used an impact to remove the pressure plate

What symptoms were you having that led you to believe there was an isue with the clutch?

~Alex

 

[jonnywong]

4wheel and 2wheel. like i said i took it to a tranny shop and it was torn down and put back together - nothing wrong there. Even had them look at my tcase and it was good.

Heres what the clutch and flywheel look like

 

[alex22]

were the fingers of the pressure plate touching the clutch disk or did you just wipe it down with a rag?

 

[alex22]

My new clutch disk was .325 thick if that helps.

 

[jonnywong]

didnt wipe anything down with a rag, so its possible they were touching i suppose

 

[scottmcneal]

Have you check your gears, IE rear and front ends? I have never heard of a clutch causing it to grind like your saying

 

[ChiXJeff]

That pressure plate & flywheel both look burned to my eyes. Personally, I'd replace both.

 

[5-90]

I agree with Jeff - looks like the cover and flywheel both have some fairly serious "heat checking" - which is usually caused by "floating" or "riding" the clutch pedal (read: "bad technique.")

If the iron is heat checked, then replace the pilot bushing and TO bearing out of hand - they're going to have been overheated. Also think hard about swapping out the transmission input seal while you've got it apart, since it's in line for a heat-related failure. You'll kick yourself if it it starts leaking in a couple weeks and you didn't do it now...

The critical measurement on the friction plate isn't the overall thickness, it's the thickness above the rivets. Compare that to new, but you'll still have friction left if you end up "clutching on the rivets." And, that's what will wreck parts more than anything.

But, do you see that band of blue on the flywheel? That shows high heat - and resurfacing (whether it can be done or not) isn't going to fix that. Replace it outright, and you'll have done a better job for yourself.

As far as the grinding noise you'd heard, I concur with trying to start moving in second or reverse - and see if that replicates it. Also, since you say the noise only really starts once you've let the clutch all the way out, I'm tempted to say it's in the transmission itself. If the noise is present when taking off in second and reverse as well, you've probably lost the input bearing. If it's just in first, it's in the geartrain somewhere - like the shift forks, first gear synchroniser ring, or something like that.

 

[scottmcneal]

start to drive a little then all the sudden lots of grinding and no movement. no grinding in nuetral


This is what i don't get.. I never heard a bad clutch causing this.. GRINDING that is..I know jeeps are strange, but hey that can't be that much..

 

[alex22]

But, do you see that band of blue on the flywheel? That shows high heat - and resurfacing (whether it can be done or not) isn't going to fix that. Replace it outright, and you'll have done a better job for yourself.

So are you saying that the flywheel cannot be ground/cut and then re used because of the changes that have occurred in the structure of the metal? Or is it because the clutch is not adjustable on our vehicles? If it is the latter, I saw shims in the Goodson catalog (.015 iirc)

The main reason I ask is because I work in an automotive machine shop and have resurfaced LOTS of flywheels and just ground them until they were clean and recut the step to the spec distance, if there was one. This is the first I have heard about replacing the flywheel because of bluing caused by heat.

~Alex

 

[wycowboy]

The surfaces of the clutch disc look pretty good to me, a little worn but not too bad, but the flywheel and pressure plate are both burned pretty bad. This tell me that someone in the past went cheap and just replaced the disc. Replace everything while you have torn down. The throwout bearing could be the cause of the grinding if its bad enough, you'll have a new one in the clutch kit. Check the clutch fork also, if the throwout bearing seized it ruined the fork and that will be obvious. Thats the only place I can see maybe causing a grind in your clutch system, otherwise it has to be in the transmission.

Chris

 

[5-90]

So are you saying that the flywheel cannot be ground/cut and then re used because of the changes that have occurred in the structure of the metal? Or is it because the clutch is not adjustable on our vehicles? If it is the latter, I saw shims in the Goodson catalog (.015 iirc)

The main reason I ask is because I work in an automotive machine shop and have resurfaced LOTS of flywheels and just ground them until they were clean and recut the step to the spec distance, if there was one. This is the first I have heard about replacing the flywheel because of bluing caused by heat.

~Alex

Correct. Once the metal starts to change colour, the problem is in the microstructure and not the surface finish. You get hard spots (which I referred to as "heat checking") and microcracks in the surface - which will expand. When? Depends on when they want to - either when you're trying to grind the thing, or in use later. No way to predict.

(NB: Heat checking is why race sanctioning bodies specify the use of special bellhousings - commonly known as "scattershields" - or the use of a "shatter blanket" around the bellhousing on manuals. At high crankshaft speeds, a flywheel can literally explode - and it's not pretty.)

If it weren't discoloured, I'd say to go ahead and grind - and let us all know how you do it successfully, so we know as well (save us all a few bucks.)

Is it possible to correct the discolouration? Maybe, at best. It would require a heat-treatment oven and some time to experiment - neither of which I have at the moment (or I'd say send the thing to me after you replace it, and I'll see if I can't figure something out.) However, if you can't correct all of the discolouration (which means that you've sorted the microstructure change problem,) the best thing to do is melt it down and start it over as another part - the melting and recasting damned sure will fix the problem.

 

[lawsoncl]

Have you drained the oil out of the tranny and checked it for debris or metal shavings?