A Treatise on Spin Control

[Sharif@Forged]

This was posted by Scott Siegel who works for Forged, and is also a well know driving instructor. If you ever get the chance to have this guy ride shotgun with you around a track, you should jump at the opportunity.

I was discussing a customer’s recent spins on track with him and I ended up writing enough about catching a slide that I thought I would share: (in addition to working at Forged I run a small driving school and instruct for all the _CA's - PCA, BMWCCA, FCA, SCCA, NASA, Chin, MVP, etc...)



As for getting the wheel back to the right angle, they call it CPR - Correct, Pause, Recover -

Correct - As the tail goes out (yaw angle increases), you have to Correct (put in counter-steer/opposite lock/lock). Honestly, this is usually the “easy” part. Most people intuitively steer into a slide and catch the “first” slide. That said, when you are really on the limits you sometimes need to put in a LOT of lock (often 180 degrees of steering wheel angle, also known as “crossing elbows”) QUICKLY. There have been a few videos circulating lately where someone new to the track counter-steers 1/8th of a turn of the wheel (45 degrees of lock) slowly and is surprised when they spin off the track. If you watch pros that are really “wheeling it” they often put in 90-180 degrees of lock almost INSTANTLY. I honestly think that the people that put in 45 degrees of lock and then go through a slow lazy spin that should have easily been caught might play too many video games with a wheel that only has 180 degrees from lock-to-lock. A real car usually has 540 degrees from lock-to-lock.

Pause - you have to feel for the yaw to Pause. Basically, as the tail swings out (increasing yaw angle), the yaw RATE (speed that the yaw angle is CHANGING) goes from near zero to a lot in a hurry. *IF* you are going to "catch" the slide, you should be able to feel the yaw RATE (how fast the yaw ANGLE is increasing) slow, and then stop or Pause. This will be at the largest yaw ANGLE, but as soon as the yaw stops increasing, your yaw RATE is zero, or Paused. A drifter tries to hold the angle here at the max yaw angle (with near zero yaw rate). A road course driver wants the yaw angle to reduce. The trick is to get the yaw angle to reduce under control and stop at zero yaw angle.

Recover - If you have "caught" the slide, your yaw angle should begin to reduce. As the car swings back toward pointing in the same direction as it's traveling (zero yaw angle) you must get the wheel back to straight, or Recover the "lock" you put in. This is really the most important part; you *MUST* get the steering wheel back to straight before the car gets back to straight (zero yaw angle). If the car swings back to zero yaw angle and you still have the wheel pointed into the slide, the momentum of the tail will just keep swinging to the opposite side like a pendulum. Most people catch the first slide; it's being too slow on the Recovery that makes them snap in the other direction.

It's generally MUCH better to recover too quickly, than too slowly. If you recover too quickly the yaw RATE (remember, rate is how fast yaw ANGLE is CHANGING) will slow or even stop - when the yaw RATE is zero, the yaw angle isn't changing. Ideally the yaw angle stops as the car is straight, but if you recover too quickly the yaw rate might go to zero while there is still some yaw angle in it. Usually the yaw angle will begin to increase again - another tail-slide in the same direction it was. Putting a little more lock in it should again slow the yaw rate - feel for the Pause, and then you can Recover again. This is MUCH better than having it whip back and forth.

Thanks,
Siegel