Stock Clutch Failure at High RPM?

#1

I had what I think is a strange catastrophic clutch failure this weekend while racing my E30 at Laguna Seca. (Unfortunately this particular race wasn’t SpecE30, but we’re working on that out here in the West!) Before everyone says "Operator Error" in unison, let me explain. Clutch was very new – less than 2K miles (engine break-in) and 2 race weekends. Failure happened on the straight between T4 and T5. Go to upshift from 3 to 4 (using the clutch, not a speed shift) and while taking it out of 3rd I hear something I don’t like, then (still with the clutch in) can’t get it into any gear. Definitely wasn’t a "money" shift as I didn’t even get it in gear. I slowed up as I tried to get it into any gear but couldn’t. Parked on the outside of T5 right by the safety station and was pushed by the safety crew back behind the fence.

Back in the paddock I noticed an RPM related vibration and the sound of some crunchy bits from what I think is the bell housing. Tranny seems fine and it goes into all gears no problem with the motor off. (Also had the owner of a local transmission shop who races a 240Z check it out briefly.) Seems like the clutch won’t disengage and something physically broke/came apart in the clutch. I hadn’t heard of this but some quick googling comes up with this quote from a page on the Ireland Engineering site for an E30 racing clutch: "If you often rev your engine above 6500rpm the stock discs will come apart." I’m currently running a Conforti chip with the limiter at 7 grand so that would definitely put me in that category. (I know that isn’t SpecE30 legal…)

Anybody heard of such spontaneous clutch combustion? (I also know SpecE30 wouldn’t fall into this category with the stock limiter set slower than 6500, but I thought I’d ask.) Also, any recommendations for a beefier racing clutch? Obviously I’ve got to keep the stock flywheel so we’re only talking clutch, pressure plate, etc.

Thanks in advance,
-Joe

#2

First I’ve heard of that happening! I also use the Conforti chip when racing KP or in GTS, though I still normally shift in the 6500 range instead of winding it to the limiter. I replaced my stock clutch last summer with a Clutchmaster stage 1 from Bimmerworld as a preventative measure, since I had no idea how old the clutch was. (I must admit I nearly cried as they put the stock flywheel back in the car…) Feels much different than the stock clutch, neither better or worse, just different.

What club was at Laguna Seca this weekend?

#3

I think I’ve had the same problem and it turned out to be the springs on the pressure plate being broken. I suspect I overreved it on downshifting one too many times, when there is no overrev protection.
cheers,
bruce

#4

What exactly broke in the clutch? That is somewhat important. I find it unlikely a disc itself would fail more likely the bands or pressure plate somehow. I have a chip for my 318 that revs to 7200 RPM and I’ve never had an issue. It’s also a 215 mm unit so rotational speeds are a bit greater.

We highly recomend the clutch masters stage one organic unit for cars like these if you are rough on the stock one. It should be super durable in cars like these and is very easy to drive. Option of sprung and unsprung hub too. Upgraded pressure plate bands and springs and what not.

UPDATE/EDIT

Don’t be scared when you look at the pricing on our site on the CM kits btw. The pricing is about to be updated…going lower surprizingly.

Post edited by: robweenerpi, at: 2006/05/09 16:09