The engagement point had slowly changed, which was partially due to wear on the drive lugs that mount to the flywheel and partly due to the worn disc.

The front disc wearing more is an inherent problem with a twin disc, and it is compounded by carbon's increasing coefficient of friction when it heats up. So the front disc sees more pressure sooner, so it heats up first and holds most of the load when you don't do the "warmup procedure". If this was used only at the racetrack and only driven after the "Warmup procedure" then you most likely wouldn't see as bad of a wear difference between the two discs.

At least that was the impression I got from the Exedy tech guy.

Fitz

Any updates wrt to longevity, track performance etc?

I know that they recommend switching the disc back and forth on drift/track cars every few events.

I know that Calvin Wan (you can see the pics I posted) used his set-up for a few seasons (heavily abused) and in the condition in the pics it started slipping in 3rd but he was making a little over 400whp on a decent single turbo.

I think this is a good investment for a weekend warrior. You can probably swap the disc every 10k miles to make it last.

EDIT!!!!!

I know that they recommend switching the disc back and forth on drift/track cars every few events.

I know that Calvin Wan (you can see the pics I posted) used his set-up for a few seasons (heavily abused) and in the condition in the pics it started slipping in 3rd but he was making over 400whp on a decent single turbo.

I think this is a good investment for a weekend warrior. You can probably swap the disc every 10k miles to make it last.

Im going to measure mine to see where they are at. Like I said, the disc started slipping in 3rd in their current condition. Who knows how much the worn and un-even surface of the pressure plate and intermidiate plate have to do with this.

I am going to have the cnc shop machine it smoth and throw it in with the worn disc and just see what this clutch can do with this much abuse on the disc.

So basically it has exceeded all specs for minimal wear, lets see if itll hold 300whp on twins....when I get my car running...lol

Would be interested to know what those disks are at compared to min spec.

Interesting that that setup is so resilient.

Wondering if the main damage to the plate is from the recent slippage?

Yes please could you take a quick measurement of the disks?

Would be interesting to see where they really start to give out.

The Exedy catalog is notoriously complicated and ambiguous IMO..... evidently there is a Comp-D twin disc which is similar to what I'm currently running (cerametallic six puck discs) but is about 5 pounds lighter (25 vs 30). I don't want the carbon discs due to this whole 'swap out every few track days' things as well as some info I've heard that the carbon unit doesnt really hold past about 450 rwhp in a rotary.

Luckily I was able to source a new Comp-D from a buddy and it's being shipped to my place soon :)

I forgot to do it today, Ill hit it up tomorrow morning, I'll weigh the unit I have also.

Goodfella, so you got a Comp-D twin disc? Is the price simular to the exedy twin carbon disc?

^I guess we will find out:).


Why is it only recommended for the clutch with the carbon discs to be swapped every few track days? The carbon and the ceramalitic clutches (not discs) are the same mechanical design (the way the pressure plates work), from what I can tell.

^ NVM, Re-read the thread and the question was answered:blush:.

I'm going with ZM022SDL which is what Exedy recommended for my use. They will chatter a little but weight is less than 6lb compare to ZM022SD. ZM022SDL is currently not available and need to be ordered from Japan. I was told Exedy USA has 4 Carbon twin disc clutches available. But those should be used in track purpose car vs. street. I was told carbon twin disc are 2-3lbs lighter than ZM022SDL or almost 9lbs lighter than ZM022SD.

going to weigh and measure my kit now, ill have some info in a bit

For some reason I dont know how to carry my pics over.

Here is what I found out.

My clutch part number ZM022SBMC1

The single sided top clutch plate is 5.00 mm thick. It showed wear anywhere from 0.15mm to 0.20mm
The dual sided clutch plate is 5.35MM thick (0.35MM thicker then the single sided plate) and had the same wear on both sides from 0.15mm to 0.20mm.
The flywheel was scared but mostly flush and not worn down.

Disc #1 was 2.66mm average with a varience of +/- 0.10mm at random checks around the disc
Disc #2 was 2.50mm avearge with a varience of +/- 0.10mm at random checks around the disc

I weighed it at fed-ex on their postage scale, mine comes in at 21.76 including all the bolts, yes with the flywheel bolts too.

Here is what I noticed.

Every single surface the the disc touched it looked as though they were worn at a slight angle. The burn marks were bad but the plate did not have alot of material missing.

I believe the presure plate has come lose or was not torqued all the way or under/over torqued on some bolts more then others. Thread lock was not used.

This would explain the angle of wear on the metal and the radom reading on the carbon disc.

The disc were traying to grab at an angle of 0.10mm to 0.20mm due to uneven torque.

Thats my guess, so as beat up as these things were and given that the presure plate was not evenly torqued and as a matter of fact losing presure due to the disc getting thinner I'd say slipping at top of 3rd on a 400whp drift car during an event is not to shabby.

Im just going to have the cnc shop resurface it all and throw it in and see what it can do in its current condition.

What do I have to lose, I got htis used unit for free and everyone can benefit to see just how far down it can go and still work.

Ben

I think based on what I just found out, I would just keep tabs on the torque.

Calvins disc were at 2.66 and 2.50 which is far below 3.3 "the cut off from exedy" and really below your 3.0.

It sucks that you had such a big difference between your 2 disc.

Ben

Thank you!

And thanks for experimenting with the disk also, will be interesting to see just how far it could go.

I am wondering if the combination of a worn disk and a resurface will be too much for it however?

Is there a chance the pedestals could be shortened to accommodate the change in thickness?

And assuming new disks put back in spacers to bring it back out to original specs?

OMG!

I didnt even think of that, I guess that would be critical.

As far as the resurface goes, the plates are bearly cut into, they are just super burnt...lol I can probably get away with just sanding for some of them.

They pedestals can be unbolted, I'll just have the cnc shop make some shorter ones...lol.

As it sits right now I still have a gap even with everything worn down as much as it is. I'll try to torque it to spec and see whats left.

If both disc are 4.2 new, thats 8.4mm

Im around 5.20 combined. Then the wear on the plates combined is like .40 or so.

So Im like 3mm down from new.

Ill re-surafce everything and make new pedestals 3mm or so shorter then they are now.

This way when I rebuild the kit I have the original stuff.

The only sucky part about this whole thing is my car wont be running until the end of the year.... :(:(

Who here among us hasn't played that game before?

I am just interested incase I ever have to deal with the issue, my guess is I will not have to, but who knows its one of those things I thought about when purchasing, and has piqued my interest that it may get answered.

Please take the time to update when appropriate!

I think everyone will benifit and pull these back out the closet if it does pull some decent numbers.

Maybe there will be a need for a "2nd life pedestal kit" hahahahhaha



In a previous statement:
If both disc are 4.2 new, thats 8.4mm

Im around 5.20 combined. Then the wear on the plates combined is like .40 or so.

So Im like 3mm down from new.

I added the wrong way..lol

8.4 disc thickness
5.2 combined
loss of 3.2mm
loss on all the plates is around 0.40

Total loss is 3.6mm so thats closer to 4 then 3...sheesh.

Looks like after smoothing everything out I should take the pedestals down to 3.8 to 4 mm to get the same pressure as new without bottoming out like it would now. Taking into consideration the loss if any of the splines on the PP.

What do you guys think?

Here is a related question..

Anyone runnign the carbon variants of this clutch or others, what is your throwout bearing life expectancy?

Just checking mine, and compared to a old one using a stock clutch with many miles on it, the new one with very little mileage on it feels crunchy and binding when rotated.

What can you say about the throw out bearing?
Very interested to here what others have to say on this topic!

Wow, tons of stuff since I last checked in!

Ben, lots of good info there man, thanks! The concept behind taking the drive lugs down 3.8-4mm sounds workable in theory, I would just worry about the resiliency of the carbon discs being that thin, as well as the replacement costs of the drive lugs when you have to finally get new carbon discs. The good news is that (I'm guessing here) if/when the disc(s) decided to break apart that they would shred up and disintegrate without too much damage to the rest of the clutch components.

Also, thanks for the wear info on the discs that you have. I think the even wear of those is due to the constant heat that clutch experienced in a full-blown race car versus what my clutch sees with a mix of track and street use. I'm fairly confident my uneven wear was due to the street miles on my setup. Like Herblenny said, I think this is why Exedy recommends against using them in street cars.

Good info, thanks guys!

Im going to make new cncd pedastals so all I have to do is swap the old ones back in when I get new disc. :nod:

Anymore updates,thoughts 2yrs later?

I've got the cerametallic twin disc. It's by far the nicest clutch I've ever felt. I have a few experienced buddies who've driven the car as well, and they've said the same. It's like the perfect amount of give with all the hold I'll ever need.

I still am using my car to build vmount kits on and as soon as im done im going to throw it all together and make the new pedestals for the clutch. I do not have much experience with this clutch so ill have Clavin test drive it for me and get his thoughts.

OP sold his car a few months ago.

I've been thinking of buying one of these but with a 10k mile life span and $1000 for replacement disk doesn't seem reasonable.