rs4_saloon

You hear a lot of ppl use the term slow hands on the circuit since it's easy to spot, but your hardly hear of slow feet.

What's a good target time to show for fast feet?

I was looking over some data and wanted to see how long it took me get off the throttle and onto the brake pedal in hard braking zones and it was between .3 to .7 seconds.

If you multiple that over a lap and then over an entire race, that's some decent time.

I'm in a 997 gt3 so left foot braking into those zones isn't an option bc I will need that foot for the clutch as downshifting is also part of that brake zone.

Yet another advantage of pdk --> left foot braking everywhere.

ProCoach

First off, you are correct in focusing on carrying vMax as long as you can and make the transition as quickly as you can, without upsetting the car. Substantive gains can be made...

I can only right foot brake (steering column in the way and no need for clutch with dog box) and from 135 mph into T1 at VIR, I cover 19 to 22 feet between off throttle and on brake.

Then, it typically takes .3 to .35 seconds to peak brake pressure, trailing off as the rotating mass inertia is overcome. Cool stuff!

Veloce Raptor

Latency can really add up in terms of lap times

Matt Romanowski

It's also important to realize that while their are optimal times in general, they are different for different cars. What works.in Peter's S2000 won't work in a stock 911.

rs4_saloon

Good stuff Peter.

T1 @ VIR

ProCoach

942 to 973 feet off throttle completely to on brakes, thirty-one feet.

Good. Not as much latency as you thought, although the stepped release of the throttle is what I would address next. Look at that.

Matt, I don't think that's the case. This is a human factor, not car dependent.

rs4_saloon

Thanks Peter..yea, that was what good looks like to me (~30ft and .3 seconds). The year prior was BAD both from the foot latency in switching pedals and also the the throttle release.

winders

Be quick, but don't hurry.

-John Wooden

ProCoach

rs4_saloon

What's also interesting is how we are taught over and over how important it is to release off the brake in a smooth manner (nice slope for brake pressure release) so that we don't disturb the chassis and violently don't toss the weight around.

however, why is it that we can violently get on the brakes from a full throttle and minimize the latency of foot switching? Is that where setup (aero - rear wing & springs) really come into play when we aggressively get on the brakes firmly from full throttle.

ProCoach

On the former, you're introducing (more often than not) a direction change and integrating an additional control input (steering) when choreographing brake release.

On the latter, confining the transition to one-axis simplifies matters tremendously. The platform is more equally distributed (weight on tires), the 911 being particularly good with static weight distribution to allow a more graduated pitch motion foward retaining that balance, and the inertia of the rotating parts MUST be overcome as the cF comes up and the pad/rotor temps normalize.

It's not simple, when you consider all factors, but the execution is straightforward! And it feels good when you do it!

amso3

When the car is traveling in a straight line approaching a turn, I don't think you can "upset" the car in the initial braking zone. So going quickly to maximum brake pressure is important. I have given this Optimum G document to many drivers in order to make the point of "fast feet". I have found that a talented amatuer driver can go from zero to full pressure in around 0.3 to 0.4 sec. This definitely helps the driver improves laptimes.

Here is the basic tip from Optimum G. The whole tip can be downloaded from my website: http://austinmotorsportsllc.com/docu...ce-information