One Lap Around Buttonwillow Raceway
This ariticle originally appeared in NASA SpeedNews in August 2016
In the middle of California’s Central Valley lies Buttonwillow Raceway, a technical circuit with 16 different race configurations and the option to run clockwise or counterclockwise. With so many options, it’s possible to run the same track several times a season and still experience new challenges.
Now that officials have revealed which configurations we’ll be running at the Western States Championships in October — No. 1 and No. 25 counterclockwise — we can offer NASA members a tutorial on how to get around the track as fast as possible. Fortunately for those racers coming from another NASA region, these two configurations are rarely used. That means there won’t be much home-field advantage for Southern California racers.
Buttonwillow can be a difficult track to master, with lots of sacrifice turns, rapid transitions and a bit of elevation change thrown in for good measure. The short front straight doesn’t quite level the playing field for the high-horsepower cars in relation to the better handling cars.
Repaved in summer of 2014, Buttonwillow Raceway’s surface is as good as it’s been in years. There are still some bumpy areas to keep things challenging, but the tar strips and repaired patches that wreak havoc in the rain are gone. Grip is good virtually everywhere, tire wear is acceptable, and track records have been falling ever since it was repaved.
Let’s take a look at the track, turn-by-turn, in the configurations you’ll be seeing at the Western States Championships.
Sunset is Turn 1 for configuration No. 1 and No. 25. The left entry curbing is a good brake reference. Carry momentum and turn in where the left curbing bends right, toward its end. Use the banking to aid turning and add steering briefly at the apex before rolling on the throttle and unwinding to track out over flat curbs.
Lower-powered cars can carry full throttle through turn-in with intention to late apex the first right-left pair of corners. Ease off the gas to scrub speed and feather the throttle for the next right-left. Roll back on the throttle and line up to use all of the flat, right side curbing.
Turn in to hug the inside white line while feathering the throttle. Allow momentum to carry the car to the outside curbing and straight-line brake toward the turn-in reference. Turn-in is at the end of the right-side curbing with a gradually increasing steering input for a late apex, where the inside curb ends. Slowly position the car at midtrack to minimize the distance to the next corner.
Enter from midtrack, driving over the right curb at the first kink so the momentum carries the car to edge of the track on the left. Straighten the wheel and brake to scrub speed before easing the brakes with a late entry for the second right kink to line up with the right-side curb. Heavy brake in a straight line then transition left immediately after the right curb to maximize the turning radius through the uphill section and apex at the crest of the hill. Breathe the steering at the crest to avoid oversteer at touchdown. The track opens up at the exit. Use all of the track on the right and bring the car back to the left side for the fast right bend before Riverside. With full throttle, transition right, early, slowly and smoothly. Hold the wheel through the right-hander to track out and position the car right of center to set-up for Riverside.
Feather the throttle at turn-in if necessary to hug the inside curbing at the entrance. Stay tight and on throttle with eyes up. Hold a steering input that hugs the inside and carries the car to the outside at corner exit and sets up for Truck Stop (No. 1) or Dog Leg (No. 25).
Dog Leg (No. 25)
Configuration No. 25 uses the Dog Leg, which bypasses Truck Stop, Bus Stop and Club Corner. As you exit Riverside, bring the car gradually over to track left so you can steer with slow hands to clip the apex on the right of the slight kink. The key here is to avoid any scrubbing of speed. Gradually line up on the right to prepare for Grapevine.
Bus Stop (No. 1)
Hold the steering at the exit of Riverside to enter on a smooth line. The track is bumpy at the apex of the left kink and the car is really moving. Experiment with the line to find a position that doesn’t upset the car too much, but allows you to line up for the Bus Stop on the left side curb with wheels straight for heavy braking.
Use heavy braking parallel to the left side curb. Braking on the flat curbing will cause the car to rotate toward the apex – use this with caution. Momentum is critical, as well as early throttle here, so use the entire curb at the apex and all of the track at exit as it opens up. The steep curb at the exit can catch a car that carries too much speed, but it’s risky to count on it every time. Steer out briefly to follow the way the track curves before turning in smoothly for the right sweeper, hugging the curbs on the inside and tracking right of center to set up for Club Corner.
Hold the steering right and transition left so that the car touches the white line on the right before clipping the apex on the left. Be mindful of how much curb you can use before it throws the car off-line. Some cars can be flat on gas through the apex, others will have to feather the throttle at the transition.
Braking is tricky because the track drops away in the middle of the braking zone. It’s even more dicey on the No. 25 configuration because you’re carrying so much more speed. Brake hard before the crest, ease the brakes to prevent lock-up over the crest and then reapply the brakes hard in the compression. Turn-in occurs almost immediately after touchdown. Think: brake, ease, brake, turn. Hug the inside curb and track out to set up for Cotton Corners. There’s time before and after this turn to complete the downshift for Cotton Corners, so pick a gear that allows you to carry momentum.
There is a lot of grip to brake while the track inclines upward. Turn in late to late-apex the first left at the crest and don’t let the car drift out more than left of center. Get the car back over to the left side to set up for the 90-degree right. Turn-in and apex the right-hander so that the car is just right of center before turning in to the final left bend. It is critical to maintain momentum for the last two turns and still set up for a “textbook” apex that allows early throttle application.
There are a few different lines to enter Off Ramp, ranging from apexing the left side line at corner entrance to a midtrack corner entry. A tighter line requires more rotation midcorner while a wider line takes a longer path and leaves the door open for passing. Feather the brakes to scrub speed while cornering and then straighten the wheel for full braking. Scrub more speed with rotation by trail braking or staying off throttle well after turn-in. It’s tricky to find a reference for braking and turn-in so keep your eyes up, work on maximizing your arc through Off Ramp, getting the car turned down to the inside and unwinding the wheel as soon as possible to get back on throttle. If the car pushes out to the right-side curbing before the right-kink, then you’ve done it right. Transition right for an early apex at the kink and let the momentum carry the car to the left side curbing for entry to Sunrise.
The entrance curbing provides a good brake reference. Turn-in is done in two motions: one to follow the contour of the track as it curves in and a second one to turn down to the apex. The apex is late at the end of the inside curb. Carry speed, go back to throttle early and track out to the exit curb. Caution: if the car slides through Sunrise, point it to the outside and go for the dirt rather than let it rotate to the pit wall on the inside!