Ronnie's Blog about CMP! Here we go!
Round 2 of GLTC is at Carolina Motorsports Park next weekend, so I decided to dive into some suspension geometry.
I ran the first event at COTA without having done any suspension tuning besides a basic string alignment so, as expected, the car was a bit of a handful to drive.
The first improvement I made was installing a honed_developments full roll center correction kit. Correcting your roll center after lowering the car basically reduces the amount a car leans during cornering without the need for stiffer springs or bigger sway bars.
I put the car on scales to set the new ride height which is now 1/4" lower, did a quick garage alignment, and then I started to think about tuning a few things.
I'm not a suspension dynamics expert or an engineer, but a little bit of curiosity and common sense usually ends in a bit of fun and learning something new. So I decided to dive into tuning Bump Steer.
Bump Steer is basically change in your toe as your suspension goes through compression or droop. The goal is to have as little change in toe as possible. I don't have a bump steer gauge so I had to come up with something using basic tools in the garage. I came up with using a lazer level and a piece of cardboard which I placed 6ft in front of the car to plot points on. I raised the wheel up to my normal ride height and plotted points with a sharpie for ever 1/4 inch in both compression and droop. I played around with my tie rod end height until I was satisfied with the curve. It took little time, but I was able to tune my bump steer to nearly zero in both directions.
Putting the time into tuning a car and then going out and getting to experience the positive changes on track is very exciting. Even if the changes don't work out the way you expected, you'll never walk away empty handed. You always learn something new and it opens the door for new ideas and more opportunities to experiment.
Round 2 CMP Practice and Qualifying: A Rough Start
It was our first trip to Carolina Motorsports Park so we did testing the day before the event. We completed 3 successful sessions before the car began cutting out in a few corners and then completely died coming out of turn 9.
Looking at the data log, it initially looked like it was a pedal position sensor which we replaced, but it didn't fix the issue. After chasing wires for some time, we found the DBW throttle body had locked up. It seems the gears inside the throttle body bound up from the aggressive rumble strips on the corner exits. We were able to release the throttle plate but unfortunately it wouldn't be the only time the rumbles would cause a problem.
Another issue we realized after testing was the brake pads wouldn't make it through to Weekend. I was getting 4 events out of a set of pads last year but it looks like COTA took it's toll and CMP is pretty hard on brakes as well. We couldn't find anyone with the pads we needed but luckily @alessandrini_racing saved our day by supplying us with some lightly used @hawkperformance
DTC60's . They weren't the right size so we had to modify them by cutting down the sides but it worked!! Thank you DJ!
During the warm up lap in qualifying, the car began to cut out again and the dash went black. I made it back to the pits to discover the battery had worked its way loose from its bracket and it broke one of the posts. That was it for qualifying and since I didn't put in a single lap, I would be starting from the back of the grid.