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2015 Autocross Solo Guide
Chapter 5b: Driving Techniques, Inputs - Throttle
Chapter 5b - Driving Techniques: Inputs - Throttle
Throttle
Throttle is a fairly straightforward topic, but long enough that I decided to cover it separately here. First, turn off any and all traction control systems. I don't think the Miatas have any, but we'll need to make sure, as the NB might. We also need to learn whether it stays on/off when you turn the car off. Unless we're talking really high HP cars & very, very advanced traction control systems geared toward racing, it will always be slower and intrusive. Regardless, learning how to deal with power and tires slipping will be good driver training. Peak acceleration is with a little slip anyway. Don't worry about shifting either. All you need to do is go from 1st to 2nd and stay there, so go ahead and clear that out of your mind as one less distraction to worry about. Once you get to 2nd gear you're done. Both hands on the wheel and no need to think about it again until you cross the finish line.
The most important thing about throttle application is that you need to roll onto the throttle, not stab at it. Again, you want to be quick but smooth. The throttle is not an on/off switch. This is a little bit more difficult to apply since our cars are underpowered and we can get away with a little more as far as getting on the gas. However, even if we don't have enough power to break traction under normal circumstances, mashing the gas won't net any significant time.Abrupt throttle application can upset the balance of the car/suspension and result in a loss of grip and acceleration. With a high powered FWD car, for example, the initial burst from an abrupt throttle will shift weight towards the back, away from the powered tires, making it more likely to break traction in the front and therefore result in slower acceleration. Obviously with RWD you want the weight to shift back onto the powered wheels - as you load the rear you give yourself more traction in the rear, which then gives you the ability to accelerate faster - however, this has to be a smooth process in order to maintain traction. It is a difficult balance between being smooth with the throttle and yet not lazily slow in trying to do so. It doesn't mean you can't go wide open throttle (WOT) quickly - you can and should, as long as you have the traction to do so.
Traction, and therefore throttle application, will depend on the surface you're driving on - wet or dry, asphalt or concrete, bumpy or smooth, hot or cold, and whether the tires themselves are hot or cold. Especially in the colder months of the season, tire temperatures and the time of day (which heat you run) can have a significant impact on the car's overall level of grip. You just have to experiment & learn via seat time what the car/tires can do. Regardless of condition, being smooth with the throttle will let you accelerate as fast as the car physically can.
I won't get too technical into limited slip differentials (LSDs) but we are fortunate to have some mechanical variant in both Miatas. Viscous LSDs tend to wear out and become open LSDs toward the end of their lives, so I don't think we should be too surprised if the NA spins a tire trying exit a corner, especially since the tires aren't as fresh as the NB's. The NB has a Torsen LSD and should be good as long as we maintain the fluids. It's important as a driver to know what the car has in order to explore what it can do. In this case, you should be aware that with an LSD, you can get on the gas a little bit earlier than without, which will also train you to be smoother. It will allow you to exit faster, and overall carry more speed throughout the course. Remember, you want to get back on the throttle as soon as possible. As soon as you're past the apex (sometimes before), you want to start applying the throttle, quickly and smoothly.
Finally, you never want to be coasting at an autox. This is somewhat of a generalization, and the mindset here is more important than the physical input. In general, you should either be braking, accelerating - however quickly or slowly, or have some kind of maintenance throttle.
Next Chapter - Driving Techniques: Braking
