About 10 years ago, three NASA Utah drivers each discovered the track in our own ways. For me, I showed up at Utah Motorsports Campus with a local Mustang club for a few parade laps. I drove the tail-end Mustang and we were told to “keep up” for what turned out to be two very spirited parade laps! A year later I joined NASA Utah and met John Calvin and Rod Sturgis.
John Calvin had a supercharged Saleen Mustang finished in Parnelli Jones orange. Calvin’s car had all the right stickers and parts to look and sound like a real racecar. Rod Sturgis found his white stallion out of state with almost all of the parts on his wish-list from Ford Racing already installed. Mine began its life in the most stock form of the three.
Calvin is an aeronautical/mechanical engineer by trade, who began his career working for McDonnell Douglas. Sturgis is a software engineer by trade and a good mechanical engineer to boot.
Back then all my buddies had advanced to HPDE3 and I was still in HPDE2, so I was feeling pressure to advance and go faster. I began making multiple adjustments before and during our Friday test-and- tune practice sessions and then had no idea which adjustments made me go faster or slower. Sturgis preaches to new drivers to make only one adjustment at a time and then measure the result to determine whether it was in the right or wrong direction.
Sturgis then suggested doing lead-follow sessions to film each other to see where he would pull away or I might gain on him. I might follow Sturgis for three laps and then we’d change positions and he would follow me. Reviewing video for days and sometimes weeks afterward indeed helped us. Not feeling the g-forces, watching video helps anyone resolve to go faster because it looks like we’ve wimped out in every single turn!
Our lead-follow video laps evolved into “chasing the rabbit.” Whichever of the two of us happened to be out front would take off and the guy behind would try to keep up! These exercises during Friday open-track sessions really helped Sturgis and me begin to close the gap on Calvin’s supercharged Saleen.
I don’t know if I ever had anything to offer my buddies of the same magnitude they had done for me, but one by one, we all three became NASA instructors.
We always talked about coming up with a safe way to teach finding the edge of traction without having a four-off experience. Trying to extend the life of my R-compound tires, I wanted a good, long-lasting Friday practice tire. On Toyo’s website, the R888R had the same “dry handling” number as the RR, but its tread life was better and as a bonus, it actually had a “wet handling” number where the RR had none. It was a no brainer. I found it was easy to get the R888Rs to talk. They are predictable, so pushing them a little more each lap felt comfortable — even to the point of transitioning to a drift.
That’s when I began to postulate how this audio-feedback could be used as a tool for HPDE instruction. Theoretically, you would want to drive fast enough to get the same level of squealing through every turn. It’s a great tool for HPDE students learning to drive quickly on track.
The vibrations we call “sound” are created as rubber deforms and loses its surface contact, then tries to return to its shape and grab traction again, giving us tire squeal. It’s a bit more complicated than that, but that’s the general idea. The more slip angle, the faster the vibration from the process just described, which yields a louder sound. Going fast through a slow hairpin, relatively speaking, there are lots of longitudinal (heavy braking) and lateral (turn-in) forces being applied. If slip angle is minor, then vibrations will be slower and you will hear a lower pitch tire squeal. In the same scenario, if slip angle is greater, vibrations will be much more rapid, and if the slip angle overcomes traction, the vibrations are even more rapid making a high pitch noise as your car screeches off the track surface!
The way I suggest finding the limit of grip in HPDE on DOT tires is to drive until you hear some tire squealing. Then get to where you are comfortable making your tires talk to you consistently, all the while being conscious of the feel of your tires coming through the steering wheel and your driver’s seat. Now that you are comfortable hearing tire squeal lap after lap, begin to back off. Get to where you can barely hear your tires squealing. Somewhere in this zone is the absolute maximum of grip for that specific tire.
This exercise is not limited to the Toyo R888R. Ask other drivers about the feedback they hear from their tires. Currently I’m on Hankook RS4’s for my wet-weather tires. New to them last March, I didn’t think they gave any audible feedback. We can get rain and snow here in Utah, and once the snow melted and things dried up a bit, it didn’t take long to hear them squeal. I’m guessing any good NASA +1.6 ST/TT tire will do.
For more experienced drivers, I have them drive their tires even harder. This approaches the beginnings of drifting, or having a four-wheels-off experience. So only practice this exercise in safe corners that have runoff and when no other cars are behind you. This will give you more confidence driving at the edge of grip and will help you develop a keener feel for finding the optimum slip angle.
Too much tire squeal is simply over-driving your tires. No tire squeal means you are driving too slow. But are you driving at 9/10? Maybe you are only driving 7/10? In either case, you haven’t yet approached the edge of grip. Sound from a street tire beginning to lose traction is a great way to find the edge of grip and to learn how to drive faster!
Once you have learned tire “feel,” you are ready to try R-compound tires that tend to give no audible warning — and then it’s too late. R-compound tires are all about the feel. They won’t talk to you like street tires do, but now that you’ve mastered what tires feel like at the edge, you will have the need for more speed! R-compound tires will take you there.
And if you are so lucky as to be granted permission to give rides at your track, then make sure you bring along a set of 200 tread wear tires because all the tire squealing makes for an even more exciting passenger seat ride!
Sturgis found another car that had all but one item on his dream build list for a race car — and it has a Coyote power plant! Running his same number No. 06, black rather than white, this one is caged, gutted, with advanced adjustable suspension and all the real racecar goodies. Now he can go wheel-to-wheel racing. Sturgis has been breaking personal bests every month since purchasing this car and has been making podium finishes this 2023 season.
He developed and teaches “NASA Utah HPDE Clinic” during the lunch hour on Saturdays of NASA Utah race weekends where he covers everything from brakes and braking, to aerodynamics and tire choice — and helping everyone remember to have fun out there.