Bad driving tip #8: downshitting

Downshifting is the process of selecting a lower gear, generally on the approach to a corner. Downshitting is spinning a RWD car while shifting because the rear wheels locked up. There can be multiple sources of downshitting. The simplest is to miss a gear change and put the car into 1st instead of 3rd.

More commonly downshitting is caused by people who habitually engine-brake (i.e. use the friction of the engine to slow the car down). In racing, this is wrongity-wrongity-wrong. Your brake balance should be set up with pad compounds and prop valves to provide the ideal braking balance WITHOUT the engine. As soon as you put the engine into the equation, you are changing brake balance. In a FWD car it’s not a big deal. It just puts more braking power on the front of the car, which paradoxically increases your stopping distance because your rears are doing less work. But in a RWD car it is a big deal because once your rear brakes overpower your front brakes, you will spin, even going in a straight line. Do that in a corner, and you’ll snap around so fast you’ll think you were hit.

Intentional or not, the source of downshitting is releasing the clutch pedal when the vehicle is going one speed and the driveline is going another. The driver below gets his foot caught under the throttle and can’t get the revs to match. I’ll bet if he had a do-over, he would have kept the clutch in and coasted around the corner.

 

ToS: DST & OHD

Last week we introduced the Taxonomy of Suckage with LTO (lift throttle oversteer). Suddenly decelerating mid-corner is not a good idea. In that same vein, here’s an even worse idea: releasing the clutch mid-corner. Around here we call that down-shitting (DST). The brakes are for slowing, the engine is for going. Intentionally using the clutch & engine to decelerate is a bad habit. You can get away with it on the street, but on the track it ruins your brake bias. So you actually end up increasing your braking distance when you mix the brake and clutch pedals. In addition, in a rear wheel drive vehicle, down-shitting may lock your rear wheels and cause you to spin even when you’re driving in a straight line. While heel-toe shifting helps minimize down-shitting, you don’t need to match revs to prevent DST. Just do your gear changes at the very end of the brake zone.

Oh for crying out loud, auto racing is ridiculously dangerous. The least you could do is drive with both hands on the wheel! One-handed driving (OHD) has no place on track. If you’re going to play at racing cars, learn to drive (LTD).

The 7 deadly spins

Christianity brings us the seven deadly sins.

  1. Lust: Uncontrolled desire, often in a sexual or monetary context.
  2. Gluttony: Overconsumption and wastefulness, usually with food.
  3. Greed: Hoarding of material possessions. Opposite of generous.
  4. Sloth: Laziness, mostly in a spiritual context (e.g. not praying)
  5. Wrath: Hatred, anger, range, often against other people.
  6. Envy: A desire for what others have or sorrow for their successes.
  7. Pride: A belief that you are superior to others. This is considered the deadliest of the 7.

In the church of racing (which I just made up), there are seven deadly spins (the links below refer to previous YSAR posts).

  1. Lust: Your uncontrollable desire to go faster clouds your judgement about when to brake. By the time you realize you’re going too fast, you’re fail-braking out of control.
  2. Gluttony: You overuse the clutch. It’s not a brake, and using it as one makes you prone to down-shitting all over the track.
  3. Greed: Your oversteer recovery uses the whole track: left-right-left-right. Around here we call that a tank-slapper.
  4. Sloth: You’re lazy and rely on hope/faith instead of experience/skill. As you begin to run out of track, on-track-praying isn’t nearly as effective as opening the wheel.
  5. Wrath: Your anger in the slowness or incompetence of other drivers causes you to stomp on the throttle and spin out of control. Enjoy your instant karma-supra.
  6. Envy: When you see another driver spin, your immediate reaction is to take advantage of their misfortune by passing them as quickly as possible. Doing so, you walk straight into a dope-a-dope.
  7. Pride: You’re a little too enamored with yourself and your driving ability. You can’t help but show off. You love donuts, burnouts, and drifting. Hey everyone, look at me!

FYI, the team was banned for the season.

Down-shitting

Down-shifting is an important racing skill that is often poisoned by years of street driving habits. On the street, one typically drives at low RPMs to conserve fuel. Shifting down can be done almost any time, and if one down-shifts early, the engine can be used for deceleration. My father taught me to do this when I was learning to drive. I guess this was a hold-over from the pre-disc brake era when the drum brakes alone weren’t enough stopping power. Why anyone would do this today is beyond me*. The brakes are much better at slowing down the car because they work on all 4 wheels. Brake pads are also one of the least expensive parts of a car and the labor is far less than a clutch.

Down-shitting is the act of downshifting early, releasing the clutch, locking the drive wheels, and crashing. The consequences can be quite dramatic.

On a race track, down-shifting as a form of deceleration is stupid. Assuming your brake bias is set up correctly, engine-braking ruins the braking balance by adding additional braking to the drive wheels. In a FWD vehicle, this isn’t necessarily horrible, it mostly makes the braking distance longer. But in a RWD vehicle, it could cause the rear tires to lock even when going in a straight line. Since a clumsy or slippery clutch pedal could find you dumping the clutch suddenly and going into an uncontrollable spin, downshifts should occur at the end of the braking zone, not the start.

  • OK, so there are a few scenarios where engine-braking is useful. When going down a mountain, over-using brake pads can cause them to overheat and fade. And on a slippery surface, adding additional rear brake can shorten stopping distances because there isn’t as much weight transfer to the front tires. If you’re going to use engine-braking, do it because it makes sense in the specific situation, not out of habit.