I googled it and found that it is a system that is intended to make the car shift like a lightweight flywheel but have dampening characteristics of a heavy flywheel. Apparently there is a spring or springs which allow the two masses to rotate in relationship to each other somewhat like the disc on a clutch plate but more complicated. I think that running the car hard may wear it out prematurely, among other things.

I think I will recommend to my SIL to find a good used flywheel that is not the lightweight design or the dual mass design and simply install that along with a new clutch assembly.

tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.