We haven't overpowered our '06 Corvette's factory clutch quite yet-but when you're testing, tuning, and otherwise driving the hell out of your C6 project car, the best approach to remedying a near-inevitable case of the slips is a proactive one. Our power output thus far has been increased by a 3-inch CORSA exhaust, VaraRam induction items, and a set of long-tube ARH headers, to the tune of about 33 rear-wheel horsepower overall. But with much more to come, it's only a matter of time before the factory LS2 clutch becomes a liability.
A call to late-model GM clutch specialist Spec yielded one of the company's Super Twin units. The main idea behind two clutch discs is that they yield increased frictional surface area, which improves holding ability. While the torque rating of any of the models in the Spec Super Twin line is greater than our LS2 will likely ever make, it's nice to know that the extra capacity is there. Moreover, the additional surface area of twin-disc clutch systems simultaneously allows the use of a far less aggressive friction compound than is needed for an equivalently rated single-disc unit (not to mention a lighter pedal effort requirement), which is a boon for driveability. Spec sells the only twin on the market that features all-billet construction, allowing for lighter weight and a 0.001 machine tolerance. There's also a sprung hub for smooth engagement and 1050 high-carbon steel friction surfaces for tremendous wear life and warp resistance.
While pricier than the GM LS7 clutch (a common upgrade that can handle more horsepower than a stock LS2 clutch), the Super Twin gives us an actual advantage over the Z06 clutch system. Plus, it's fully rebuildable, with kits ranging from $199.00 to $599.00 on our particular unit. This shouldn't be an immediate worry by any stretch, though, as Spec says that its first prototype (a "trim 3," versus our trim 1 unit) is still working great, despite close to 300 10-second strip passes and nearly 30,000 street miles. They're still not sure how long these suckers can last! As we're a bit short on time and space this issue, we'll give you the lowdown on how this clutch drives (and races!) in our next C6 project installment.
As clutch replacement requires removal of almost the entire drivetrain, we figured there was no better time to strengthen our transaxle. See the sidebar for details on our DTE Differential Strut. G