Tuesday, February 26, 2013

2/23 ESP Camaro Suspension Testing Recap

My 2013 Solo season officially got under way this past weekend with a test and tune day at Mineral Wells Airport hosted by Jeremy Foley. During the weeks prior to testing, I got the Camaro out of mothballs and prepped it for action. To start with, I replaced the Sparco driver seat with a lightweight Kirkey unit. Overall, it saved 7lbs - not much, but everything adds up. I also added a harness lap belt and submarine strap to help hold my hips in place when left-foot braking. I am going to be experimenting more with left-foot braking in the Camaro this year. I have experience with this technique from karting and the Bondurant Formula Mazdas, and I think it can be an advantage in autocross due to the quick, busy courses that require many more direction changes than a road course over a given distance. The instant pitch control should allow better and quicker control of the car's attitude during autocross runs...that's the theory anyway, we'll see if it works. 

New Driver seat for the Camaro (another seat cover is in the mail)
I also test fit different rate rear springs and rear coil spring perches. I made the move from pigtail-style springs in the rear to standard 5" coil springs which gives me tons of flexibility on rate and the new rear coil perch gives me better control of my rear ride height. With all this change, testing was needed though....

Hypercoil 5" springs for the rear

Packed up ready to roll late last Thursday Night
Overall, my goal of the test was to improve the Camaro's balance on the Goodyear Eagle RS tires. Last year, I suffered from too much understeer (especially at Solo Nats) and did not do enough to overcome it. This is not going to happen again. My feeling was that the rear was over-driving the front and given that I have more adjustment in the rear suspension, I started there. My secondary goal of the test was to leave with a neutral balance and have all of my rear suspension adjustments in the middle to give me max setup flexibility at races.

It was a nice day at Mineral Wells...except for the temperature which started in the 30s

Test parts laid out and ready to go
In the end, my number of iterations were limited by the severe tire wear normally seen at the Mineral Wells site. I ran through two spring iterations and on the stiffest rear spring I brought, the car came to life. It was very neutral steady state and a touch loose in the slaloms (my preference). After the rear spring got me the balance I wanted, I dropped the roll center height (adjustable on my FAYS2 Watts Link) from the top to the middle out of seven adjustments. That brought the balance back towards light understeer, but still much improved from when I started. So now I have a close to neutral car with most suspension adjustments in the middle. I took lap times and data from all of my runs, but this was primarily a subjective read (luckily the stopwatch and data agreed with my preferences). We used a 200' circle for steady state balance and a short 25s looped course with basic autocross elements. My next item to test will be a bar-sweep of the StranoParts adjustable rear ARB which should give me further fine-tuning of the ESP Camaro's balance and front spring rates (small changes here, but mainly for pitch control).

I am running two local events for practice/testing next week with my dad. The first National SCCA Solo event is around the corner, and hopefully there is more speed to be unlocked from the ESP Camaro.

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