,
Dunlop Direzza ZII Tires with a 245/40/17 specification were chosen to round out our non staggered wheel/tire package. The latest iteration of Dunlops feature a new tread pattern and a UTQG rating of 200 which is well within class requirements. When auto crossing at the highest level you quickly become a tire weenie, and often times different brand tires are chosen based on lot surface and ambient temps. Every year the manufacturers release the latest and greatest and they are snatched up by the dozens in an attempt to find out which is the fastest. Margin of difference between the slower and faster tires, forget it… It can likely be chocked up to farting during the run, yet everyone finds what works for their setup and in our case the Dunlop’s were on the list.
In addition to the wheels and tires a quality suspension is a must have to be competitive within a class, and for that we turned to Odi Bakchis at Feals. When Odi is not drifting, he is running Feals and producing coilovers for not only many different platforms, but also for specific forms of motorsport. We contacted Odi because we wanted something we thought would work well without breaking the bank. Our phone call was answered quickly and by a box with the Feal 441 coilovers. The dampers are assembled and valved by Feals and they use Swift Springs of the appropriate rate, in our case 7K in front and 6K in the rear.
 |
Feal’s also provides shortened sway bar end links with their kit. This is important since once the car is lowered, the non-adjustable OEM sway bar end links become a binding point, decreasing the bars' effectiveness. The shortened Feals units allow the bars to work properly without binding.
The final modification we made before the first event was the rear sway bar and for that we sourced one from a 2013 WRX. The WRX rear bar is larger than the BRZ unit (16mm versus 14mm)and it swapped right in using the OEM BRZ end links.
 |
 |
All of these modifications were in place within 30 days of taking delivery of the BRZ in a heated effort to start dialing in the car for the 2013 SCCA Solo Nationals. With the above laundry list installed in the car, Bart and I hit our first 2 local autocross events to gain seat time and experience in what works on this chassis. The car felt very good right away with excellent lateral grip and predictable breakaway. While Bart remarked about liking the car’s neutrality (read: loose), I thought it had a tendency to oversteer on corner exit a little too much. It was completely drivable and still very quick; however it did not inspire confidence during higher speed cornering. It did however make the car very good in the tighter/slower stuff. It was a trade off and one we both thought could be improved upon.
The links below show our overall results from our first two events in the car with the documented modifications. Finishing top 20 overall is a large accomplishment in the talent rich Milwaukee autocross region as not only is MKE home to many national champions, we also get many of the Chicago region drivers coming to our events to duke it out. Looking at the results it was safe to say the car was shaping up nicely.
Wisconsin Autocrossers Inc. Autocross Results Event #6
Wisconsin Autocrossers Inc. Autocross Results Event #7
We first turned to shock adjustment which helped slightly but we still had a large amount of body roll that seemed to drive the car to rotate or push depending on speed and steering input. We also tried a ride height adjustment by raising the car slightly but that did not offer the desired result; it was worse everywhere and as such it was lowered to the previous setting. One thing about co-building a car was that after getting some seat time in the car, differences of opinion relative to how to improve handling started to appear. Different driving styles can potentially call for different changes and so Bart and I began discussing (pissing and moaning at each other) how to approach the next set of modifications. My idea was to leave the coilovers and spring rates alone as the car felt really good for how soft it was, making it forgiving on different surfaces, and to use larger roll bars to control body motion and for that you can guess who we called…
“Hello Whiteline, our BRZ needs your help”
click….. errrrrrrrrrrrrrrrrrrrrrrrrr
