Premature clutch wear. 1st vs. 2nd gen?

Aaron Turner synfinatic at
Mon Aug 12 09:15:03 PDT 2013

So I've been trying to diagnose why my clutch slips under hard
acceleration.  It doesn't slip a lot, just what feels like one revolution
or so. Happens probably 2-4 times a lap at THill depending on how hard I'm
on it.

So long story short, I have a nearly brand new (2 race weekends and about 5
track days) 1st gen Barnett clutch pack installed in a 2nd gen motor.
 (long story)   Although to be honest, the clutch has been slipping for at
least half that time (I've had bigger problems to worry about).  I tried
adding more play in the clutch cable last race round, but that didn't help.

The clutch seat & seat spring washers from the 2nd gen clutch are NOT
installed.  4 of the 6 clutch springs were Barnett, the other 2 stock.

I measured the plates.  The thicker #2 friction plate is on the high side
of being within spec.  Of the remaining 6 frictions, 4 are in spec (barely)
and 2 are just out of spec.  All +/- .02mm of spec.

Steels look good, no bluing/etc.  Pack was installed correctly per 1st gen

So, seems like I probably need a new set of frictions (I couldn't find any
spec for total clutch pack height, does anyone have any numbers?).  What I
don't understand is why the clutch wear was so aggressive.  The motor isn't
making crazy horsepower (less then 80HP) and historically my clutches have
no problem lasting more then a full race season.

I know the 1st & 2nd gen SV are *almost* the same... stator, gear position
sensor and oil cooler being the obvious differences on the bottom end, but
maybe there is something different with the clutch basket/etc that would
cause this premature wear?

Right now, the only idea I have is that the clutch cable was too tight and
that caused the premature wear.  And by the time I loosened it up it was
too late.  But honestly, I never felt any difference after adjusting the
clutch cable.

Suggestions or ideas?


Aaron Turner         Twitter: @synfinatic - Pcap editing and replay tools for
Unix & Windows
Those who would give up essential Liberty, to purchase a little temporary
Safety, deserve neither Liberty nor Safety.
    -- Benjamin Franklin

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