Clutch upgrade - What disc?
Prior to the dual mass flywheel, Porsche ran a solid flywheel and a spring center friction disc like everyone else in the world (more or less). Yes there was chatter from the springs. Porsche tried to eliminate this with a rubber center disc in 1978-1979 but they proved unreliable (they had tendency to blow apart under high stress). The reason Porsche developed a dual mass flywheel was two fold: 1.) it eliminated the need for spring center friction plates there by eliminating the noise issue, 2.) the dual mass (i.e. heavier flywheel) was a lot more forgiving moving off from a dead stop as it held more kinetic energy at idle. The down side was a heavier clutch assembly mass takes longer to build revs and the dual mass flywheel cannot be resurfaced. For the street you need one system or the other to allow enough slack in the drive train to move from a dead stop. Solid center friction plates and light weight solid flywheels are for track use only were hopefully you're rarely at a dead stop. The issues with converting a dual mass flywheel to a solid flywheel (with a spring center friction plate) comes down to your tolerance for increase noise, clutch take up feel (it’s more of an on or off feel), and ECU issues. The ECU is programmed to think it has a heavy flywheel bolted to the drive shaft, hence is will cut off fuel as you come to a stop (allowing the heavier flywheel to keep the engine spinning) prior to transitioning to an idle circuit fuel flow. This was esp. a problem on the 993 models that were converted to light weight solid flywheels and the engine would die from a lack a fuel as you came to a stop. With the more advanced ECU programming, I think this problem is now resolved (although you might need an ECU flash to make everything work right). The best way to understand what this is going to feel and sound like is to drive a 1989 or earlier 911. Even with the stock solid center flywheel and spring plate friction disc, the clutch assembly is both louder and less forgiving from a dead stop.
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Sep 2, 2015 09:03 AM
