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Evaluating wear of a puck clutch setup


ETR
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I love me some sprung puck clutch disks...contamination resistant and they tend not to hot spot your flywheel or PP quite like an organic disk does.  But... every time I've had the transmission off I've inspected the clutch and the disk measures nearly the same as a spare (new) disk on hand.  I know the flywheel and PP are taking the wear, though that's a bit harder to monitor.  

 

It's noisy in the paddock and when pulling in the trailer, otherwise works great.  We have about 8-10 race weekends on the current one.  I'll probably be changing the transmission out this winter, and with a new clutch in hand it's hard to decide what to do if it looks the same as the last time I saw it.  I do prefer changing clutches in my garage rather than a paddock, but I'd hold off if it's not time.

 

So, when did you know it was time to replace if the disk shows negligible wear?  What failure mode have you guys experienced with puck-style clutches?  

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I've replaced puck style clutch discs for hub spline wear more often than clutch material wear.

Lots of torque reversals because of shifting and on/off throttle; not much clutch slippage.

 

The application is usually more aggressive with puck style as well (no Marcel), putting more shock loading on the hub splines. 

Edited by mender
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I don’t use the sprung disc, had one break a couple springs and get jammed between disc and flywheel. But I use the solid hub disc. Only had to change one when puck fractured. Couldn’t tell driving but found crumbs in bellhousing when I swapped transmissions. Many racing miles on the sintered puck clutch 

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Also had the spring hub come an apart and lodge in between the clutch and pressure plate. Wanna say it was after 200+ hours of use so we chalked it up to letting it go too long. We still plan to continue using a spring hub, puck style. 
 

We will however start logging actual hours of use and target a replacement around 175 hours. 

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Contact the manufacturer.  They should be able to provide service limits on the pad thickness.  In the past, I was able to get this data from both Exedy and Spec. If it's well within limits, and the hard surfaces are good, send it. 

Edited by kcbhiw
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How we determined wear.

#1 does it work? If yes keep running it, if no replace.

#2 is the trans/engine out of the car? If yes Replace for $100, If no refer to question 1. 

 

For $100 we swap it while its apart since changing it at the track is no fun. If it was significantly more expensive i might leave it in. Track time is more expensive than saving a few hundred dollars on not swapping a clutch disk while its apart I figure.

Our last clutch disk was in the car for 3 years and approx. 200hrs and looked good like nearly no wear when we swapped it out. Now its our spare. 

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The secret is to always bring a spare. If you have one, you won't need it; if you don't, you will. 

 

20 minutes after I left my shop for the 27 hour drive to Laguna, I realized that I had left my clutch spares by the door so I would see them and bring them. Not a problem, I thought, the disc had about 30 hours on it and the wear was negligible. Add a renter who was new to the car. A missed shift, a slide backwards into the gravel, attempts to get unstuck and - yup, he burned up the clutch disc. And yes, I had also left my fold-up engine crane at home, too.

 

So after a bit of research re: Fiero V6 clutch discs and a quick trip to the local parts store, a borrowed engine crane and a few bruises from holding the transaxle in midair while my co-mechanic slipped the 4 cylinder Jeep clutch disc in place, the Fiero was ready for Day Three. Always a challenge swapping clutch discs on a Fiero, even more fun in a parking lot. ;)

 

Day One? Two hours in, one of my guys leaned on the fuel rail while checking the oil. Yup, he cracked it: gasoline fountain. No spare fuel rail, no junkyard that had one for a 2006 Malibu 3500, so silver soldered it and reassembled, ready for Day Two. See above.

 

Day Three: Actually got about three hours of running before the clutch master gave up. No spare. Packed up in time to watch the end of the race.

 

So Day One, needed spare fuel rail; Day Two, needed spare clutch disc; Day Three, needed spare clutch master. Got home, procured the spares. Carried them to every race after that. Never needed them again! :)

 

 

Edited by mender
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