Can anyone explain toe/heel shifting?
Originally posted by Chuck's NSX:
SJS... So do you recommend using downshifting to slow the car when approaching turns etc....? Or would you just use the brakes?
Originally posted by Zuerst:
The main advantage of down shifting is not only for fast turns or hills but in slippery conditions such as heavy rain or iced road, down shifting in those conditions can significantly reduce lose of tracks, hence down shifting in slippery condition is better then braking since braking is what makes the car loose grip...
Originally posted by ChopsJazz:
...Going Faster, Mastering the Art of Race Driving. The text book of the Skip Barber Racing School...
Originally posted by sjs:
I would disagree with that entirely. (no offense) You have much more control over the brakes than you do "engine braking", and you get to use all four tires. The quickest way to get backwards is what you suggest. In terms of traction, think of it as similar to 2-wheel drive vs. 4-wheel drive when accelerating on a slippery surface.
Originally posted by Zuerst:
The main advantage of down shifting is not only for fast turns or hills but in slippery conditions such as heavy rain or iced road, down shifting in those conditions can significantly reduce lose of tracks, hence down shifting in slippery condition is better then braking since braking is what makes the car loose grip...
Originally posted by Chuck's NSX:
These are all great posts, thanks for all the input. Here's another simple question: I don't do any track driving, although would love to get invovled. So, if I'm slowing from 60 to 0 at a traffic light let's say, should I be downshifting at all or do I use just the brakes?
Originally posted by ChopsJazz:
Losing grip is an interesting concept. Remeber that a tire, each tire, has only 100% grip available at any given time...
Originally posted by DanO:
Zuerst, with all respect intended, an engine brake in any condition cannot be as controllable as a properly biased 4-wheel brake. There are several reasons for this and I’ll touch on a few:
1) Engine braking reduces the effectiveness or renders the anit-lock braking system useless. That is, the anti-lock braking system can’t free up a rear tire that has lost traction due to engine braking. And as you say “locking of the wheel is what makes the car lose grip.” So, I think it is wise to let the anti-lock system work to keep the tires from losing grip.
2) When any deceleration force is applied to the tires, weight shifts from the rear (assuming your traveling forward <g>) to the front. As this deceleration force is being applied, less weight is available at the rear of the car and therefore there is less grip at the rear and more at the front (grip is related to weight). If you are only applying deceleration force to the rear tires, then there is MUCH less stopping potential available than if the force were being applied to the fronts. Ever noticed how fast the rear tires lock up when only using the parking brake?
3) If a driver has a choice of which tires will lose grip first (front vs. rear) a smart driver will choose the fronts. With any steering input, losing grip on the rear tires first will cause a spinning condition that few drivers, if any will be able to recover. Any of us with manual brake biasing on our cars know this fact intimately
I’m not trying to be mean or condescending; I’m just trying to express my opinion which differs quite a bit from yours.
DanO
Originally posted by Zuerst:
where as if you down shift the wheel is still rolling just at a slower rate, hence no periond of dead lock and less chance of losing traction and skid...
Originally posted by DanO:
Heel-toe not done smoothly (or not at all) will “chirp” the rear wheels during downshift and cause all kinds of balance problems with the car and wear and tear on the transmission, tires, driver, instructor and lap times.