Track Day 08 + 09 - Streets of Willow -- New PB, Caddy Brembos + Larger Pedals for driving improvement, but blown coilover!
Back to back track weekends at the exact same track? Seems like a recipe for being able to really test changes and seek improvements!
Improvements to test at the track:
Coilover bump stop adjustment: My previous two track outings had both yielded suspension understeer and then four wheel push issues. For this track weekend, a variety of elements I was looking at in different places all came together at the same, and the realization was that I definitely needed to refine the coilover bump stops. The realization came from the intersection of two realizations. The first realization came as I was reading in a Miata group how a particular Miata had massive understeer and it wasn't until the owner realized it was because they were on the bump stops cornering that they were able to resolve it. Perhaps that was my issue? Then I was trying to determine what settings to go with for a solid baseline track alignment, and after getting an alignment somebody claimed my ride height settings were ultra low. I quickly responded that I was pretty much running the baseline alignment values spec corvette recommends, which then got me curious, just how much lower than stock am I? I'd always figured I was an inch lower, and had setup the QA1 bump stops as if I was an inch lower. Welp, the stock height is 6" to the front and rear jacking points as far as I can tell... and I'm at 3.25" in the front and 4" in the rear. Now knowing this, I removed a bunch of the bump stop spacers from the coilovers, and I hope that now I will have better results.
Shifting / Heel Toe Related Stuff: The next upgrade was inspired by the fact I definitely have some shifting improvements to make. I have been frequently avoiding making a secon downshift at different parts of the track, thus leaving the corner a gear too high. For example coming into turn 1 CW @ SOW, I would be coming in pushing 105 in 4th gear. I'd start to brake, trailbrake the entry and sidefoot (can we really call that heel toe?) it into 3rd, and then brake hard for the sharp hairpin turn, venting speed down to almost 35mph to make the sharp turn. In order to get the most out of that corner exit, I need to shift one more time before the exit from 3rd down to 2nd, and that shift during hard braking I don't feel good doing with a side foot technique. So, knowing this is an area that needs improvement, I'm attacking the issue in all the ways that I possibly can: better brake and gas pedals that allow me to maniuplate the pedals better, and then an MGW short throw shifter to help keep shifts much shorter. From there, I just need to practice it at the extremes I am braking and utilizing this technique at the track. I cannot reasonably find a place to practice this technique at the braking forces that I experience on the track.
Alignment values: The last update to the Corvette is an alignment, as mentioned a bit in the first paragraph. Having put the car on coilovers and wider wheels + tires along with inadvertantly loweirng it during that process... it occured to me the alignment was also possibly a part of the issue and now off. So I established some target specs based off the PFADT brand recommendations considered alongside with spec corvette recommendations and got them over to the local alignment dude. I aslo removed the spacers behind the upper control arms to help me get into the -2.8 camber area or so in the front.
Brake improvements: The stock C5 brakes just felt horrible at the last track day, likely in part due to the massive weight gain associated with the wheel and tire size increase. The additional braking effort was causing me to absolute mash the crap out of the pedal to get less braking capability than I'd like, and quite possibly resulted in me absolutely blasting through the remaining brake pads I had. To hopefully combat this, I now have 14" C6Z06 rotors, Cadillac brembos, C6Z51 rear brake brackets and 13" rotors, essentially forming a poor mans big brake kit that will hopefully yield improved braking power and feel, while also hopefully not absolutely blasting through brake pads at too high of a rate.
Improved GPS data: I picked up a Qstarz BT-Q818XT, which is a Bluetooth GPS receiver that samples GPS data at 10hz. Why does this matter? Well if you're using your phone, it samples at 1hz, which is 1 time per second. That results in data that jumps around a bit and isn't terribly accurate. Switching to 10hz will allow me to get data 10 times a second, resulting in a much smoother and more accurate GPS result.
Tire Pyrometer: One thing I have heard a lot reading and talking to folks about handling issues, is that nearly all of them say without a tire pyrometer you're taking a lot of shots in the dark in regards to handling. So I purchased one, and I intend to log the tire temperatures all side to side and center on all 4 corners every time I come off the track! Also, check out the log I made for docuumenting tire temp and pressure values
How the Track Weekend Went
The first track day began as a bit of a shit show. Freezing temperatures the night before combined with low day temps and wind kept the track very cold. Apparently everyone who drove up from warmer coastal locations missed the cold track memo though and were spinning out all over the place. I had a frontrow seat to several spinouts. I wanted to drop down a group to get out of the overly hungry folks, but wound up sticking with my group and it went decently. The changes I'd made to the suspension helped a bunch, and the brake upgrades combined with the heel toe pedals made it so I could control my RPMs and shift gears while braking into turns. Not too shabby! I did however have issues with wheel hop exiting turns, and only tied my previous lap times of 1:29. I still had a good time.
The second track day had much nicer temperatures, with the track heating up much faster due to less wind as well. The morning still had some rather extravagent spin outs and one crash, with one in particular having a fellow crash all the way through the hot pit fence and launch his wheel into the sky. Overall though the day was good, and the more I settled into the new braking setup the more I was able to put down strong times. Unfortunately, the wheel hop I'd experienced the previous day became quite crippingly and prevented me from exiting turns on the throttle. I still was able to put down a personal best of 1:28.162, over a second quicker than previous times. Not too shabby!
Unfortunately, it turns out the wheel hop issue appears to be related to a blown coilover. Score another negative experience for me and these QA1 coilovers. They blew up after just three track days.
Takeaways for the next track day:
I don't actually really have any. The car felt absolutely amazing to drive with the bigger brakes and the awesome pedal situation. The only minus to feeling the blown coilover causing wheel hop on exits. I can only imagine what it'll handle like when I can put power down on my exits. I'll hopefully be able to pick up a full second on my lap times.
My next upgrades are mostly going to be safety related. A roll bar and a harness are in short order in order to ensure I can safely stay planted in the car in the event something unfortunate happens. Added bonus though... I'll be a lot more planted in the car and hopefully that will translate to better confidence driving.