AC coupe

But getting out of the throttle early means, unless you are already at top speed, losing speed and time. Even at turn 10 at the glen you want to be on the brakes ( if you have to that is) the minimum amount of time possible to hit your target turn in speed and shift the weight.
Let's say you and I both had an apex speed of 90 there but while I lifted early, you stayed on the gas 20m longer and used a touch more brake...you would be ahead of me on the other side.

Larry Herman

This is where I differ with your comparison. If you lifted a touch earlier, trading the harder and later braking for more entry speed with a "less unsettled" car, you may be able to have a higher apex speed, say of 94 or 95 mph. Your higher entry speed and speed through the corner would actually put you ahead of me even though I may have gotten back on the gas earlier.

Additionally, I have found that in some corners where I really can carry some apex speed, I actually end up getting off the gas LATER because I do not have to slow the car as much. That said, each corner needs to be evaluated for which technique works best, and that is what the data can show you.

AC coupe

amen to that!

ervtx

This is why I have been saying... threshold braking = using 100% of the tires' braking traction. If you're not intimately familiar with where the changing limits are by occasionally approaching them, you're going to inadvertantly exceed them. Changing tire temps, track conditions, brake bias, etc. have a way of turning a grooved braking pattern into something that exceeds the threshold.

If ABS engages on the street, I say "thank goodness for ABS".

If ABS engages on the track during threshold braking before turn-in, I say "OK, there's the limit; brake sooner next time".

If ABS engages on the track at/past turn-in, I say "oh ****" and make a mental note to threshold brake the next time around to recalibrate my safety envelope.

+1

bobt993

^^^^ Actually the use of ABS during turning is vital to using it to drive fast around a race track. Feeling ABS in the steering is proper use of the inside wheel slip. Feeling heavy pulsing in the brake pedal would be excessive. One of the single most advances in my driving was adapting to the proper use of ABS ( as coached from a pro racer) for precisely what your suggesting is a bad application. This is a big part of motorsport ABS systems and how they used in race cars. If you look at long G data for front straight such as Summit and Thunderbolt, you are looking for proper application by the driver of ABS into the corner on a modern 4 channel system. Sorry to disagree.

KaiB

The terms motorsport ABS, modern 4 channel and its activation on inside wheel slip remain foreign to many of us in the sense that either they cannot be used due to class restrictions or $$$.

Great post however.

ervtx

Bob, I actually tried to avoid drawing the conclusion you challenge, so no need to apologize. I'm not racing; just DE'ing my daily driver. So for me, ABS engagement is a sign that I'm at the limit (instead of just inside the limit). I intentionally worded the ABS reference in the first person ("I say [to myself]...") in order to emphasize that this is what I do for safety purposes, not what others should do to improve lap times.

FWIW, this is consistent with all of my previous posts on this topic - that threshold braking should be a foundational safety skill for everyone vs. an advanced skill for racers only. Feel free to disagree on that if you like I know first hand that Skip Barber and LSRPCA structure their instruction programs around this very idea. I know of at least one local non-PCA DE program that does not. So there are indeed varying schools of thought. A worthy debate, IMO.

bobt993

KaiB, 15 year old Porsche factory 4 channel ABS systems were available on the 993 with the ABD option. Even at the street level settings this system provides big benefits when used properly. The systems have become very sophisticated on the newer street cars especially the GT3 variety. This along with aero is why it is very hard for a vintage 911 to compete effectively in stock classes that include newer cars.

bobt993

Russell , there is good material on this subject that you may want to read. One article that came up not too long ago was written by Patrick Long and it is pretty good about detailing how he likes to use ABS as much as possible on a race track. You are likely still using ABS, but feel it more in the pedal when it is excessive. Try gripping the steering wheel lighter and start "feeling the application on turn in". You can also evaluate this with a good data logging system that has fast sampling on the accelerometers (100hz range). Limit the smoothing on the long/lat G's and you can watch the ABS work effectively on balancing traction into the corner. The beauty of ABS is it can really expand the friction circle plot when used properly.

ervtx

LOL! I've seen Patrick demonstrate this in my car first hand (1:07)
I can trail brake that turn, but I'm relaxing the brake yards ahead of where he's still on them pretty hard.


FWIW, I'm identifying ABS engagement on the basis of the ABS light on the instrument cluster, and the obvious vibration from the pedal; if it's engaging in a more subtle manner, then I haven't registered that as ABS engagement.

ProCoach

Yes.

winders

Maybe we all aren't using the term "threshold braking" the same way.

Here is a quote from Page 76 of "Going Faster!" (Skip Barber Racing School):

Don't Start By Going Deeper
The most common mistake that drivers make when they turn their attention to getting the last bit of lap time available at corner entries is to drive closer to the corner before braking---going deeper.

Going deeper, first of all, should be reserved for high-speed-loss corners where threshold braking will be used. It is very seldom that threshold braking will the appropriate technique to use in every corner entry situation on the track. At Lime Rock, for example, there are six corner entries for every lap; only one involves threshold braking, and there is some active discussion about that one.

This text is in keeping with how I was using the term "threshold braking". Maybe I am using the term incorrectly.....

Scott

Veloce Raptor

Coming into this late, having been out opf town...coaching.

Amen to both these points.

Amen again to both points!

PedroNole

I think you're using the term correctly. I just think the discussion went sideways when you said, generally, that it wasn't faster and therefore not that important... I think the ensuing discussion has been really good and people maybe now have a better grasp of why/where it is necessary to use it to go faster.

winders

Pedro,

That's not what I said. I said that "Getting better at threshold braking isn't going to make you a lot faster" and it is not the "most critical braking skill to learn". I never said we shouldn't learn it or use it.

I too think the discussion has been very good. But, I don't know that we are all using the term "threshold braking" the same way. Some folks are "threshold braking" everywhere on the track they use the brakes. That's why I think I may be using the term differently than some of the others in the discussion. Like I said, I may be using the term incorrectly but it seems to match with the book I quoted previously.

Almost all of my experience on the track is motorcycle related so I could be all wet in regards to cars.

Just trying to learn through discussion....

Scott