Another post from the "N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i Forum".
Quote:
Originally Posted by XPO186
Justin,
Certainly sign me up for the 7.5kg version as a package deal with your forthcoming twin/multi disc clutch 
Hey Phil,
the 10 kg "Single Mass Steel" flywheel that is
currently in my car and our forthcoming 7.5 kg "Track" version, will be different in design to the flywheel used in the multi-plate setup we are now doing for my vehicle.
It will obviously be a single mass flywheel and will also be made from chromoly steel that has been nitrided, however it will be machined to allow the multi-plate basket to bolt up to it.
If you Google "multi-plate" clutches and find an exploded view of one, you will see what I'm talking about.
We will be designing our own single face clutch kit to be used in conjuction with our 10 kg & 7.5 kg flywheels.
Many of you guys will simply not require the clamping force of a multi-plate, in particular if you
do not plan to go 1/4 mile racing, running 275 "Hoosier" drag radials.
Cheers.