[bhill86]

Ok quick question. Had a chance to blast the clutch disc today and noticed two things that raised questions.

#1 the metal between the friction material looks like it’s warped. I assume that should be flat?

#2 I also noticed a small chip in the friction material. Never dropped the disc or anything so I’m not sure how it occurred but should I replace the disc due to this?

Thanks.

[Tom Vaught]

Who made the disc?

Tom V.

[b-man]

#1 - it’s supposed to be wavy like that to provide some cushioning, called marcels.

From Google:

Marcels - A clutch disk with marcel construction has the friction material of both sides backed by thin metal plates. Between these two plates are thin bowed pieces of steel (marcels), which act as springs when the disk is sandwiched between the flywheel and pressure plate.

#2 - buy a new disc, cheap insurance against possible failure.

[bhill86]

Tom, it’s a LuK.

B-man, thanks for the answer to #1. I looked an an old 11” I had laying around and noticed it looked similar but less pronounced so I wasn’t sure.

[bhill86]

I ended up picking up a new clutch kit to be safe. As it happens #1 the discoloration in the metal of the old disc someone commented in my other thread about possibly being from heat is also present on the brand new disc so must not have been heat on the old one.

Also, as it happens, the new disc has some similar spots on the edge which leads me to believe the “chip” on my old disc may have been there the entire time. O well, I have an extra disc and pressure plate now I guess.

Question though. I cleaned the new flywheel and new pressure plate but do you guys clean the new disc itself before installing?

[Tom Vaught]

Originally Posted by bhill86

I ended up picking up a new clutch kit to be safe. As it happens #1 the discoloration in the metal of the old disc someone commented in my other thread about possibly being from heat is also present on the brand new disc so must not have been heat on the old one.

Also, as it happens, the new disc has some similar spots on the edge which leads me to believe the “chip” on my old disc may have been there the entire time. O well, I have an extra disc and pressure plate now I guess.

Question though. I cleaned the new flywheel and new pressure plate but do you guys clean the new disc itself before installing?

When the disc is manufactured the bonding material for the disc is the resin that winds up on the surface of the disc (front & back side) after it has been used for a while. The discoloration in the metal of the disc is not the issue.
The issue is if after a period of use the clutch system exhibits chatter down the road. If that is the case then blasting the front and back surfaces of the disc will clean that resin off and the disc will probably never need to be replaced (since it is a LUK) in the next 10+ years.

The disc I blasted (also a LUK) is about 15 years old now.

Tom V.

[bhill86]

Thanks for the response Tom. I know the discoloration isn’t the issue. I just thought it was worth noting. I should probably update my old thread. That’s where a member suggested there may have been excessive heat in the old disc that caused the discoloration, an assessment I agreed with. I guess that’s not the case since the new one also has that.

I’m a little disappointed I didn’t get to test your recommendation on blasting the surface but I was unsure about that chip I found in the old disc and thought it was a better option to replace the disc and PP since it’s not a lot of money. In retrospect, after looking at the new disc, I suspect I would’ve been fine to run the old disc.

Curious to see if I still have chatter. Last year I changed the pilot bushing and throwout bearing. This year I installed a new flywheel (unplanned), new clutch disc and pressure plate. Unrelated I also replaced a worn transmission mount. Everything is back together but I haven’t had time to test drive it yet.

[Tom Vaught]

Everything takes time. People have lives to live too (above and beyond Pontiac vehicles).

If you have chatter, it is telling you the clutch system is not contacting the parts in a proper manner.

LUK makes good stuff. Hard to blame LUK when a few minutes with a Glass Beader machine and some proper abrasive with clean the excess resin off the surface.

Tom V.

[bhill86]

Well I’m happy to report I got some time for a test drive today which also happens to be about the only day in the near future it isn’t supposed to rain here and I’m calling my issue FIXED.

At very low RPM with light clutch engagement there’s a hint of chatter but with any increase in RPM or further engagement of the clutch it’s smooth as silk. Huge improvement over what it was and I’m hoping maybe as the clutch breaks in that small amount of chatter will disappear. If not, I can live with it.

I appreciate everyone’s input in this thread and my previous. I wish I could say for sure what the exact cause was before but at least I know if it happens to return I have the option of blasting this disc or using the other disc I already blasted. Hoping that’s not the case though as I’m pretty sure last time the chatter occurred it was immediate.

Thanks again.

[Tom Vaught]

Glad it is much better. You posted you have a LUK clutch system.
One of the best out there.

Tom V.

[Tom Vaught]

Glad it is much better. You posted you have a LUK clutch system.
One of the best out there.

Tom V.

[bhill86]

I’m happy with it especially considering the cost.