Clutch discs - with or without sprung centre?

[billjam]

I am shopping for clutch parts and I'm wondering what determines whether I should use a disc with sprung centre or solid centre. (or should that be center? ).

The application is a daily driver '88 Carrera with a 3.6 conversion. Flywheel is lightweight 1992 RS with a 90-94 964 pressure plate mated to the original '88 G50 box.

I can see that the sprung centre might be kinder to the transmission. Is that the only advantage?
It seems like there is a mix of sprung and unsprung discs used across all models without any apparent logic.
It also seems that discs are pretty much interchangeable from 1987 to well into the nineties - correct?

[Bill Verburg]

Originally Posted by billjam

I am shopping for clutch parts and I'm wondering what determines whether I should use a disc with sprung centre or solid centre. (or should that be center? ).

The application is a daily driver '88 Carrera with a 3.6 conversion. Flywheel is lightweight 1992 RS with a 90-94 964 pressure plate mated to the original '88 G50 box.

I can see that the sprung centre might be kinder to the transmission. Is that the only advantage?
It seems like there is a mix of sprung and unsprung discs used across all models without any apparent logic.
It also seems that discs are pretty much interchangeable from 1987 to well into the nineties - correct?

There are only 2 sorts of street clutches available
1) spring center
2) rubber center

both absorb shock from clutch actuation, the rubber absorbs gear rattle a little better, the rubber is very heavy

the rubber center has been problematic in the past and most have been replaced over the years w/ a spring center, the rubber center was oe for most model 911s from the '70s

I'd use a spring center clutch, that was what was used on the 964RS, the part #s have probably been superceded as the same clutch was used thru late 997 GT3s

[bazar01]

The dual mass flywheel (DMF) uses the unsprung disc. The DMF does the dampening instead of the disc.
Since you have the lightweight FW, i would use the spring centered disc.

[Bill Verburg]

Originally Posted by bazar01

The dual mass flywheel (DMF) uses the unsprung disc. The DMF does the dampening instead of the disc.
Since you have the lightweight FW, i would use the spring centered disc.

forgot about that one
here's a dual mass setup from a '93 964, top left is the dual mass clutch disc, top right is a normal RS type spring center


the dual mass clutch is incompatible w/ the 964 RS flywheel, only the rubber center or spring plate versions are

here's a complete 964RS setup