I was at Lime Rock yesterday, and spun going through the Left Hander (Esses).

What happened was, I braked late going into the Left Hander, which pushed my turn-in point farther to the right of the track than normal. I modified my line so that I would hit the apex/track out point on the left side of the track, which brought me over the the concrete patche at a different angle than in my previous laps. I was at near or maximum lateral grip, as I had done in this section throughout the day. As you can hear from my engine tone in the video, I very gently began rolling on the throttle when I saw I would make the apex. Everything was fine until my rear tires hit the rumble patch, at which point the rear slid out HARD to the right. While I was able to catch the initial slide, it slid out from under me fast enough that I got a pretty decent slip angle - past that seat-of-the-pants point when I knew that the car would snap back around HARD. Sure enough, the car snapped right back around and overshot to the left again. I caught that spin, but then the car rebounded hard enough to spin me a full 360 degrees. I caught that spin perfectly, pointing straight ahead and moving at ~20mph. I could have continued on the track, but there was a Corvette close behind me and I wanted to quickly get out of its way for safety.

So the question of course is, why did my car spin? I believe it was the result of several factors which compounded each other. The main issue was that I lost traction when the rears hit the concrete. You can tell because the squealing begins just after the concrete patch goes under my car. This in and of itself was a bit of a surprise to me - I’ve experienced those patches become slick in the wet, but have never noticed any difference between them and the pavement in the dry. I was skirting with the edges of the friction circle throughout this section, and right before I spun I was probably just at 3:30 on the friction circle. As the audio shows, I was on the gas very slightly - just rolling it on carefully to control the balance of the car. Normally, my Miata is VERY predictable and responsive at the limit - I’ve always known exactly when the rear starts to kick out, and correcting is extremely easy. As such, when I didn’t feel anything out of the ordinary as I applied power, I continued to gradually roll on the throttle. The problem was that rear went from having the perfect amount of traction to suddenly not having enough traction, which is why the rear kicked out so fast and with no warning whatsoever.

The next question is, why did the concrete patch suddenly turn to ice on this particular lap? Here I think there were several issues at play. My tires were definitely hot, and I could feel the fronts push and be a little greasy in Big Bend in the previous lap. However, I did NOT feel any greasiness before hitting the concrete (which is why I continued to roll on the throttle gently), but that the tires were hot could have exacerbated the other issues. Previously in the day, a car had left the track just to the left of that concrete patch and spewed all sorts of dirt all across that section. The dirt was not cleaned up, and we continued to drive over it with minimal problems. But, while the dirt was mostly gone on this lap, some surely remained, and compounded the other problems. Additionally, the dirt that was on the Line was likely scrubbed clean by cars driving over it throughout the day, while the dirt off Line likely just languished until I drove over it. That is probably why the dirt didn’t cause any noticeable decrease in traction at any other point in the day in that corner. The last issue of relevance was the line that I took over the concrete. Because I had gone deeper into the Left Hander, my line across the concrete was accordingly different than in prior laps. While I wouldn’t necessarily expect a different line over the patch to yield drastically different levels of grip, something as small as a little divet or a different surface texture in the different part of the patch, compounded by the issues mentioned above, could have been enough to start a slide.

When you push a car hard for long enough, something will eventually go wrong. That doesn’t make a spin or other incident any less of a concern - a spin is simply an accident that did not happen. Had the spin occurred in a different area of the track, the outcome could have been very different. A spin is always nerve wracking, even for more experienced drivers, and this spin was certainly no different for me. It represents a moment when you are no longer in absolute control of your car, which is very scary. But, much can be learned from a spin, and hopefully the lessons I’ve taken from this incident will help my driving and ability to foresee changing levels of grip in different circumstances in the future.