In the days leading up to Hooked on Driving’s 3/12 track day at Thunderhill Raceway, I watched as the weather forecast continued to worsen. I knew I needed to do a rainy track day for the experience but I wasn’t exactly looking forward to it. It sounded a bit scary. HOD had sent newsletters and emails saying that driving in the rain was a lot of fun, but wasn’t convinced.
It was unbelievably fun! Driving in the rain is a blast! Flying around Thunderhill in a steady rain, water sliding off a freshly Rain-X’d windshield, my 350Z was perfectly planted. The Z, like most production cars, is designed to understeer at the cornering limit, meaning the front tires begin to lose grip before the rear tires do. This is much more predictable and easy to control than oversteer, where the back tires lose grip first. My rear street tires are especially wide (245 front, 295 rear) so the tail really stays planted. When the car begins to understeer, easing the throttle back slightly shifts weight forward, giving the front tires more grip to turn the car.
On hand was Guy Gamba, motorsport rep for Big O Tires in Northern California. He attends most most NorCal HOD events, reading tire temperatures and advising drivers on tire pressures and car setup. On his recommendation, I dropped tire pressures 4 psi to help get more heat in the tires. It worked. Grip was good. Tire temperature readings after track sessions were fairly consistent across the face of each tire, indicating the entire surface of the tire was being used. Had there been more rain and standing water, I would have added pressure to round the face of the tire to help resist hydroplaning.
The first clip is from a very wet lead-follow session. We followed coaches for two laps, then they followed us for two more to check our performance. It was a great learning tool.
The second clip is from later in the session after the coaches left us.
Thunderhill is the perfect place to do a rain event. There are few walls. Most of the track has lots of flat dirt on both sides. The paddock has two large canopies to park under. The track also has a skidpad area where we ran a figure-8 course in the wet to practice drifting.
The only bad thing about the rain is that it turned the brake dust from my track pads into cement. I usually coat my wheels with wax before an event, but didn’t get to it this time. Even after hours of cleaning, I still haven’t gotten all the brake dust off.
Another fun part of a track day is seeing, and being part of, the car show in the paddock. There are always a lot of great cars in attendance. This event was just before a Historic Motor Sports Association (HSMA) weekend. Those folks brought some very cool cars, including a tribute BRE Datsun 510.