A couple of people have asked my why I upgraded the Penske dampers with ones from TracTive. It’s pretty simple, they improve braking, acceleration and cornering while also providing a comfortable ride on the street. That’s pretty much the Holy Grail for a street/track SL-C. Here’s what Johannes van Overbeek said about TracTive.
Having spent over 20 years in professional sports car racing and having the good fortune to work with some of the best teams and winning races like the 24 hours of Daytona, 12 hours of Sebring (2x) and the Petit Le Mans (2x) I have driven on nearly every damper you could name.
As I learned about TracTive it was clear they have a completely different technology than anybody else in the market. Driving it for the first time was a revelation. You really could, finally, have the best of both worlds. A car that was compliant on the road and an animal on the track.
If there is such a thing as horsepower for the corners, this is it.
I finally have the vast majority of the CNC parts for the rear suspension upgrade. The only stock part is the lower control arm, everything else has been completely replaced. Improvements include semi-active dampers, shim-adjustable camber, improved bell crank ratio, lowered roll center, improved anti-dive, improved rotor cooling, no binding of the push rod and upper control arm, and the ability to easily switch the bell crank ratio between Street and Track mode which changes both the ride height and wheel rate. All of he parts are machined from 7075 which is closer in strength to mild steel than 6065.
Right rear upright viewed from the engine compartment side. The top piece is the upright bracket which allows shims to be slid between it and the upright to facilitate easy/predictable camber adjustment. The extension on the top right is for the toe link. This is cleaner that the stock approach and provides more room for big brakes. The bracket on the left is for motor-on-caliper parking brakes.
The seam at the top with the horizontal bolts is where the camber shims are inserted. There are none shown.
Right rear upright viewed from the tire side. The four tapped holes on the outer edge are for a carbon fiber brake duct cover.