Clutch Failure Analysis - Need your Help! (pics inside)

[allcoupedup]

A LUK clutch RepSet pressure plate and clutch were installed about 500 miles ago and pulled today. I pulled it because there was extreme judder when disengaging the clutch - had this symptom since mile 1. I believe the flywheel is original and it was resurfaced in a flywheel machine before the install. Everything was clean as a whistle before installation.

Flywheel obviously got hot and has heat cracks - but only on the inner half of the disc/flywheel contact surface.

Clutch disc shows wear on the inner half of the contact surface:

Here's the interesting part.... the pressure plate and flywheel exhibit matched heat spots. I marked the flywheel/pressureplate relationship and have marked the matching heat spots in the picure below:

Any ideas? I can't see anything obvious on the disc or the pressure plate and need some facts before I try to get a replacement set from LUK. Could the flywheel have been cut wrong? Could I have broken something during the installation?



thanks in advance
Brian

 

[wishuwerehere82]

It looks like there may have been insuffient holding force on the disk, allowing it to spin the clutch plate. Or the linkage did not have enough free play in it to completely disengage.

However much they cut the flywheel it wouldn't make any difference in the gap between the flywheel and pressure plate. I would prefer a spring type pressure plate over the finger type for positive engagement.
Think about a 12" inch clutch if you're going to be cranking on it.

 

[Hib Halverson]

Looking at the images, I'd say either

1) The clutch had a lot more than 500 miles
2) It was subjected to very severe duty in those 500 miles
3) it was slipping for much of those 500 miles.
4) The flywheel was not machined.

In any event, you need to start over. The PP and the disc are probably junk. I'd take the flywheel to a good machine shop and see if it can be machined again.

 

[allcoupedup]

Hib,
The clutch had 500 relatively easy miles on it and it isn't behind a beast -- just a 327. No slipping either - just severe juddering as it the clutch disengaged. Flywheel was machined on a flywheel grinder and was shiny clean with circular grinder marks. I probably should have yanked it after I drove around the block a few times but....... .... I didn't.

thanks,
Brian

 

[wishuwerehere82]

I don't know Hib,
That flywheel looks pretty well cracked to remachine.
I would suspect that it was cracked initially before the rebuild and got worse.

 

[JonM]

This is a guess...but seeing as it only had 500 miles and everything was new or machined...I am wondering if the clutch plate may have been put in backwards.

 

[jerrybramlett]

The six special bolts that hold the pressure plate to the flywheel are shouldered. It is possible for them to bottom before the pressure plate is fully tightened down if the flywheel has been surfaced too much. You can test for this problem by installing the clutch on the flywheel outside of the car.

One of the main causes of clutch chatter is a worn pilot bushing. Did you replace the pilot bushing when you installed the new clutch? What does it look like now?

Another common cause for clutch chatter is misalignment of the transmission with the crankshaft. Did you use a stock GM bellhousing or a Lakewood, Zoom, etc. aftermarket scattershield?

 

[allcoupedup]

JonM -
Can't happen - if the clutch disc is flipped the springs hit the flywheel bolts... it isn't even close.


Jerry,
The bolts I used on the pressure plate were just standard bolts - I'm confident the plate was all the way down... just checked a pic from the assembly and it was...


I have a brand new pressure plate and clutch sitting here and looks like I will need a new flywheel. Definately don't want this to happen again!

 

[Rowdy1]

But Why?

I'd need concrete proof of why it looks like that before I put it all back together again. I changed out my clutch and pressure plate last year when I blew the T10 and ONLY becuase the new trans had a different spline. I had over 7,000 miles on the clutch and pp, and believe me, more hole shots and gear slamming than you can imagine and it was like new. I have the old assembly in the box and I'd put it in if I had to simply because of it's condition, it looks NOTHING like what you show. I'm really tied up or I'd take a few pics. and show you what I'm talking about. That's a misalignment or an adjustment problem, I can't tell you what my driveline has seen but for 500 miles not raced, even if it was raced, that's NOT what it should look like. I'm guessing constant contact between the plate and clutch, you should have had trouble shifting and getting it in gear because the clutch wasn't disengaging. I want to know what you find, let us know.

 

[Ken]

See why there are steel bellhousings (scattershields)? How'd you like to spin the flywheel to seven grand Lou? :L

 

[IH2LOSE]

Sorry for your troubles,your photos are excellent.


So some quick questions

Did you ever start the car in gear? Did the starter drag and act lazy as if the car was still in gear? How did the car shift,was it trouble some or no problem, This might tell us if the clutch was not fully disengaging.(disengaging= seperating the clutch from the flywheel and pressure plate)

How was the performance of the car,did you notice it was off,If you nailed it in top gear would she take off or did it seam as if the clutch was slipping?

Did you compare the old throw out bearings,were they the same hieght/If your replacement throw out bearing was taller then the proper one it would never allow the pressure plate to fully mate up to the clutch and would cause the problem you have because the clutch would always be slipping.

In looking at your fly wheel from your photos,

When mine was resurfaced I had very clear cross hatching from when the plate was refinished I dont see that in your photos was your fly wheel resurfaced? Do you know if it was check for squareness with a straight edge,

were you able to adjust the clutch when it was installed new to the proper specs ?

Are you sure that when you installed the clutch that the throw out bearing was captive in the clutch fork ? How was the ball and the clutch fork? You know a little bit of slop here and there with a bent,wrong lenght or worn out clutch fork,incorrect ball stud,worn clutch linkage,worn ball studs and missing plastic retainers for the Z bar could all add up to not allow the clutch to also not disengage,What is the over all condition of what I listed above.

Sorry for all the questions,but to have a clutch look like that after only 500 miles is criminal and we have to diagnoise the entire set up not just the clutch plate thinking it may be defective.


Good luck

 

[Rowdy1]

I Do

See why there are steel bellhousings (scattershields)? How'd you like to spin the flywheel to seven grand Lou? :L

I "usually" shift at 7,000, and I DO have a Lakewood scattershield. I've seen parts stuck in the ground, asphalt from coming apart, luckily they went down and not through the floor board:eek

 

[jerrybramlett]

The bolts I used on the pressure plate were just standard bolts

The high strength pressure plate bolts are shouldered for a reason. The shouldered portion fits the hole in the pressure plate more snugly than a fully threaded bolt. This makes the pressure plate center itself when you bolt it down. If you use fully threaded bolts, the pressure plate can be installed very slightly off-center and therefore out of balance.

I'm not questioning the safety of using an aftermarket scattershield. I'm only pointing out that they are notorious for being out of spec for transmission alignment with the crank.

What did the pilot bushing in the crankshaft look like when you removed the clutch?

Your photos make me think your clutch was slipping too much of the time (not fully engaging). How much free play did you use at the top of the pedal travel?

 

[allcoupedup]

Sorry for your troubles,your photos are excellent.


So some quick questions

Did you ever start the car in gear? Did the starter drag and act lazy as if the car was still in gear? How did the car shift,was it trouble some or no problem, This might tell us if the clutch was not fully disengaging.(disengaging= seperating the clutch from the flywheel and pressure plate)


How was the performance of the car,did you notice it was off,If you nailed it in top gear would she take off or did it seam as if the clutch was slipping?

Did you compare the old throw out bearings,were they the same hieght/If your replacement throw out bearing was taller then the proper one it would never allow the pressure plate to fully mate up to the clutch and would cause the problem you have because the clutch would always be slipping.

In looking at your fly wheel from your photos,

When mine was resurfaced I had very clear cross hatching from when the plate was refinished I dont see that in your photos was your fly wheel resurfaced? Do you know if it was check for squareness with a straight edge,

were you able to adjust the clutch when it was installed new to the proper specs ?

Are you sure that when you installed the clutch that the throw out bearing was captive in the clutch fork ? How was the ball and the clutch fork? You know a little bit of slop here and there with a bent,wrong lenght or worn out clutch fork,incorrect ball stud,worn clutch linkage,worn ball studs and missing plastic retainers for the Z bar could all add up to not allow the clutch to also not disengage,What is the over all condition of what I listed above.

Sorry for all the questions,but to have a clutch look like that after only 500 miles is criminal and we have to diagnoise the entire set up not just the clutch plate thinking it may be defective.


Good luck

There was plently of play and there was no dragging or slipping. I could have the car in gear and hammer it at 3000 RPM and the clutch grip was solid. TO bearing was seated in the folk correctly - I check even peeked into the bellhousing to make sure. TO bearing is correct and the stud is correct - I'm using a stock 403 bellhousing. I don't think it was dragging at all because I should shift easily. Haven't checked the flywheel or pressure plate but I bet one of them was machined incorrectly and only the inner area of the clutch disk was gripping and it generated so much heat upon disengagement that it burned up the flywheel.

Yeah.... I'm not too happy. I shoulda pulled it apart as soon as I realized there was a problem. The car shook so badly as I let out the clutch that I was worried about breaking my crank.

Brian

 

[IH2LOSE]

I still think you have a releasing problem,I have never seen it as badly as yours being scourched more towards the inner then the outer but if you think about the way the springs are in the pressur plate the outer would want to pull away first. Scary thing not positively knowing what went wrong, then having to put the whole thing back together,

When I am diagnoising a problem I always start at square one and make it perfect,then move on to the next componet in the system,Again this might not be a major problem but a bunch of little one all together can give you the results you have now,

Please keep us updated on what you find

AGAIN SORRY FOR YOUR TROUBLES

 

[allcoupedup]

Thanks! I am definately scared to put it back together again and have it happen again. Can't even imagine how some guys feel when they paint their car only so see solvent pop all over.... ad

Brian

 

[studiog]

allcoupedup, Could you smell that clutch burning up when you were driving? Seems like it would have been an aweful smell to be that bad in just 500 miles. Hope you get it resolved.

 

[I_R_DA_ONE]

It almost looks like the bolts on the flywheel were not torqued to the right specs or the bolts maybe to long and bottomed out..... This is a serious situation....because my 66 blew the flywheel at about 6500 rpm and it cleaned off the back of the motor and tore up the firewall.... Dew check the throw out bearing as some one mentioned also.... It is always a good policy to change it when changing the clutch...not expensive to do....

Mike

 

[allcoupedup]

Hey guys - the flywheel bolts are the correct part # from GM + the crank flange holes are through- holes so they couldn't have bottomed out. Flywheel was cast in late 1964 and worked just fine with my old clutch. No clutch burning smell..... I give up! TO bearing was new and the correct length.

Brian

 

[tigernut]

Brian,

Have you called the LUK clutch company? I assume they must have some type of tech support number.

I'd be interested in what they say (not that they will admit a problem with their clutch, even if that ends up being the case).

I'm looking into buying a LUK repset as well in the next few weeks.

Doug