bobt993

What Scott is saying is also true with 4 wheels. Drivers fall into regression when they have worked to a certain level and are looking for that last bit of time. The assumption is " I must brake later and be more on the limit all the time". The end result is an erratic lap with a bunch of "oh sh*t" moments. The reward in the end is usually a couple of tenths maybe .5 secs. When you look at the data you see bad trade-offs and a typical drop in mid corner to apex speeds. The driving style is very digital, hard gas, hard brake. The car is upset in the transition through the friction circle and losing valuable grip. My comment when sitting in the right seat is either " Are you in a hurry to go slower??" or "Your spending a lot time over slowing to get more on the throttle harder, it may feel faster, but......".

The first patch is fixing corner entry by removing the brave late braking efforts so the driver can feel the proper entry speed. Once the corner speeds are consistent and ingrained you can introduce a bit more of aggressive braking and harder throttle on corner release. We had a driver in this very scenario before a big PCA race at Tbolt and he went from chasing the front cars to winning his very next race with consistent smooth corner entry.

Veloce Raptor

Exactly 100% spot on. I work on this prettty much with every driver I coach. In fact, a very experienced Cup car racer sent me some video recently regarding an issue he knew he has. His braking is excellent, but he is just a hair too early & hard on the gas, and thus (typical 911) he lifts the nose of the car, causes sudden understeer, then has to lift & correct to get the car back on line after the apex & at track out. In the end, it's hindering his exit speeds even though he is on th egas sooner. His best aproach is to wait a hair's breath longer before squeexing on the gas. Slightly more elapsed time to get to throttle, but he uses ONE throttle instead of several.

Everyone should watch Sir Jackie Stewart's video interview (shirtless...yuck) of how to drive a car smoothly.

ervtx

Scott, I for one, have not taken issue with your first point (getting better isn't going to make you faster). It's your second point that I disagree with (whether or not it's the most critcial skill to learn). I'm not sure if there's a universal most critical skill to learn (vision?), but the context of your comment could lead people to believe that it's somehow a "lesser" skill compared others.

I appreciate your Skip Barber reference. But be careful... the quote does not provide Skip Barber's actual definition. It does not say "threshold braking is...______.". It just describes when and when not to use it, which supports your first point, (but not your second).

I have a Skip Barber Handbook from 2007 that does provide an explicit definition. It is portrayed as Part 1 in a 3-part disection of the braking process (p18).

1) Threshold-Braking: straight-line braking with the tires delivering 100% of their braking traction (or when they are rolling 15% slower than the actual rolling speed of the car).

It goes on to describe their procedure for finding the optimal braking point (p19):
Their rationale behind this progression is not about "going deep", it's about calibration. So although it does not conflict with your first point, it does conflict with your second point. Skip Barber preaches threshold braking for the purpose of establishing an objective baseline from which the optimal trail-braking effect for that turn can be determined... remember, this is Skip Barber; it's all about trail-braking As such, they view it to be a critical skill to learn.

"Drivers who are proficient at threshold braking, brake turning, and trail-braking will have lap time advantage over those who haven't learned how to use these techniques." (p18).

-------

An interesting bit of physics insight - also from Skip Barber - on why even threshold braking should be arrived at smoothly versus abrutly:
In other words, insufficient weight transfer to the front, robbing the front tires of additional braking traction.

Clearly, Skip Barber does not equate threshold braking with the kind of hard and abrupt braking habits that have been attached to the term in some of the prior posts in this thread. Hence my opinion that we risk giving threshold braking an undeserved, bad rap by equating it to something larger than what it really is. Some of the best parts of this discussion for me have been the insights that break down the whole process into smaller, discrete chunks that can be individually understood and practiced.

bobt993

Russell I think what Scott is saying to put it bluntly is most drivers so over-use the brakes they basically park the car before the corner, then WOT to try and catch back up. The reason you can get on the gas so hard is the lack of corner speed. The car is very agitated by the back and forth balancing, but is functioning well below the limit.

Larry had originally asked how to learn this technique and I will say it again get someone in the car that can coach you through the process. This is the single most critical step in improving track driving/racing ability. I am sure you can eventually pick it up on your own, but why bother? Intense in-car coaching can get this down in a couple of days and the skill will apply to any car you drive.

winders

ervtx,

In "Going Faster!", Carl Lopez outlines "The Procedure" taught at Skip Barber. He states on page 77:

"The Procedure" is an established way to work on improving high-speed-loss corner entries.

He references "long braking zones" for this. He also says that you should consider abandoning threshold braking when "the speed loss at the corner entry requires less than a full second of braking."

He goes on to describe why lighter braking, say 75%, might be better. That description entails better control of entry speed, better control of the car, and more consistent throttle application.

Do I think that "threshold braking" is a lesser skill than say "brake-to-throttle transition" or "throttle-to-brake transition" or "trail braking"? Maybe not. But, since the last three are used much more often than the first, I think they deserve more emphasis. Over braking seems to be a much more common problem than under braking. That is my opinion based on teaching motorcycle racing techniques. As I have said multiple times now, this could be incorrect in the four wheel world.

Scott

ProCoach

Scott, I saw Carl two weeks ago at Lime Rock at the Historics.

He's a wonderful man and one of several who penned "The Procedure."

His addendum is but one of many that have been added over the years.

I prefer my colleague Bruce MacInnes' definition. You'll have to hire him for access to that!

Google "Bruce MacInnes"

Remember, most of the problem with over-braking is not braking too hard, it's braking too long...

winders

That may very well be the case on four wheels. In my experience racing bikes, it was braking too hard. Racers trying to reduce the time on the brakes while braking later, mismanaging it, and going slower because of it....

Scott

ervtx

I got that several pages ago, and have never disagreed with it. I'll stop trying to make my completely separate point about skill acquisition since it is relatively simple and did not advocate any particular frequency of skill application that needed to be debated for this long

winders

Peter,

Let me modify what I wrote.

Yes, braking too long is a problem for motorcycle racers as well. But, in most cases, braking too hard was a bigger issue and fixing that made the biggest difference in overall lap times. This was because the racers were more consistent had fewer "moments".

Scott

ProCoach

Scott, I still think that braking more softly in areas that can sustain threshold braking in the quest to be "more consistent (and have) fewer moments" is treating the symptom rather than the disease!

Just finished a weekend with Spec: Race Atom and much of the difference between drivers is that the quicker guys spend less time (hence distance) slowing because they're pushing the pedal harder... Nearly everything else is the same.

Throttle pickup then becomes the next major priority. It's not enough to let off the brake at a slightly higher speed than you think you ought to to carry speed in and through the corner, you should seek to quickly stabilize the platform by picking up more quickly and progressively on the gas...

YYMV...

winders

Peter,

What is the disease? Not enough skill.....

Doing anything on the track to the very limit of or exceeding the driver's skill is inherently more error prone. Can we agree on that? The drivers that manage driving at or near the actual limit the best are going to be the fastest. They have the most skill. Hey, if it were easy, everyone would be fast, right?

Drivers have to find the point where they are likely to start making errors, where their skill runs out, and step back from that when racing or trying to set good times. Otherwise, they will make errors and, at the very least end up going slower. At most, theor day could be over way ahead of schedule.

Practice is the time to try and extend one's limits, to increase one's skill. This is where you can try to exceed your limits in appropriates places and when you are not going to put another persons car or body in jeopardy.

Of course, we see examples of people trying to do things in races they just don't have the skill to do. At the club level, that is not the best thing to do. Racers frown on other people wrecking their cars.

The more quality practice you can put in the more you are going to increase your skill. Practice does not make perfect. Practice makes permanent. So you have to practice the right way if you are going to increase your skills. This is where data acquisition and coaching come into play. Understanding where you can improve and how to improve are key.

Scott

cello

Truth. The Ross Bentley adage is 'perfect practice makes perfect'. Without some form of data coaching, practice devolves to 'groundhogs day'.. do the same thing over an over, get comfortable, convince yourself thats the limit, wonder why you cant improve, change something on the car, etc. Good discussion all.

Matt Romanowski

X a million. Good call.

Veloce Raptor

+2


On a completely different topic, this past weekend I was instructing at a PCA event here in Texas, as well as teaching the classroom session for the most advanced run group. We ran Texas World Speedway clockwise. Sunday morning, I arrived at the track and went to mess with my car in its garage, only to find a totally flat LF tire. Not even 1 PSI of air, totally flat. Thankfully I always bring at least one spare wheel/tire, so I removed the flat & put on its replacement.

Inspecting the flat, I found no obvious penetration or nail, etc. I thought, perhaps it is a leaking valve stem, which has happened before. Nevertheless, I did a visual inspection of the outer & inner parts of the rim, as I always do when I take wheels off the car, put wheels on, as well as immediately before & after each track day. In fact, I had intended to inspect then on Saturday evening, but we had a big cookout/beer bash at the track......and I forgot.

Outer surface was fine. However, on the inner bead area, I observed a small hairline crack about 1" long. I hadn't hit anything, including curbs, so it had to be metal fatigue. I have a total of 9 track wheels, 4 of which are several years older then the other 5. This was one of the older ones. I have decided to trash the other 3 older ones and order 4 new ones. The 5 newer ones are flawless.

Bottom line: just as I coach my clients, inspect your gear as often as physically possible. Wheels break. How often have we read about that here on RennList? Don't forget "just that one time" as I did. I am very, very lucky that tire was flat, else that wheel could have disintegrated on track, and the LF is the load bearing tire with this clockwise track configuration.

Wheels are consumables. I brought my cracked wheel into Sunday's classroom to hammer home this point.

cannon1000

Can someone explain the use of curbing?

I understand using it on the inside wheels to straighten the turn...but I have heard from others that it can be used in other ways as well. Can you expand?