what could have caused this

[matt]

It's a driving technique issue. Specificially lack of heel-toe downshifts

[1990m3]

that happened to the pressure plate on my e30 m3 when the pressure plate was about three months old. Not due to bad heel-toe on my car though, it happened on an upshift under normal driving condition on the street.

Sachs warrantied the part which was cool, but the labor still sucked. Sorry to see that happen to you...

BTW - when it was broken I couldn't shift between gears and I couldn't accelerate at all. Fortunately my bell housing had no signs of damage and was not scarred on the inside like yours is.

that sucks

[Rev Engineer]

Was that with the s14 motor? What clutch setup are you using on your e30s50?