Project 968 Building a Better Race Car / Part 3
The last items we can address in our suspension system to help reduce roll are the sway bars. The factory ships a 968 with 26.8mm front bar and a 16mm rear bar. The M030 option provides a 30 mm front with a 19mm 3 hole adjustable rear bar. These M030 bars are the bars that we use with some minor mounting alterations. In the front we use some delrin in place of the rubber, again to minimize lost energy in the form of deflection, which has the effect of increasing the roll resistance provided by the same bars. The other thing we do in the front is thread the drop links all the way down and we run a nut all the way to the bottom, in this way we can adjust any preload out of the system.
The rear is pretty much the same with the exception of using our own special mounts to locate the sway bar to the torsion tube (a picture of our prototype is shown below). We also utilize rod end drop links. These mounts and drop links have the affect of increasing the overall stiffness of the bar (as compared to the way it was delivered from the factory) and allow easy adjustment to get rid of preload. There are other, more expensive, supposedly better options out there but I like the performance the modified factory bars offer.
Another upgrade we have found to help the overall performance of the car on track is to upgrade to the factory M030 brake system as allowed by class rules. There are other packages which would offer better stopping power but none would meet class rules so our hands are kind of tied here. Below are some pictures of the installed big calipers and also the factory 968 air ducting which has proven to be up to the task of cooling the brakes (of course we use castrol SRF brake fluid as well, which is good to about 590 deg F dry and 518 deg F wet, so Im sure this helps as well). We use Hawk Blue 9012 pads but are starting to hear really good things about the Ferodo DS3000 and DS3000 plus so I'll be trying those soon.
That's about it for the suspension. To-date the car has progressed well. We have entered it in 3 races (2 PCA and 1 PBOC). The first PCA race was Sebring and we qualified 3rd behind two 911 C2s in class but ahead of all 944 turbos, 944S2s and 968s in class so that wasn't too bad even though it was obvious to me the car was not yet right. We didn't get to finish the race due to a red flag incident and a misunderstanding in the hot pits (long story).
The PBOC race was not very competitive and we easily won our class and beat many other supposedly faster class cars. By the PCA Road Atlanta race the car was much more correct and we qualified second in class (ahead of the 2 C2s that out qualified us in Sebring so that showed some progress) behind another C2 I had not seen before, and again ahead of all the 944 Turbos (7), 944 S2s (4) and 968s (1). We finished second in class (out of 23 F cars) for the race. We actually out qualified and beat in the race all but one of the 944 Turbo Ss as well (another car I had helped setup) so the car is doing well, however there is still more time to find I believe.