How To Brake?

[FTS]

Here are two schools of thought exemplified by two different "experts" (IMHO) on the topic (excerpts taken from Racer University):

Neil Roberts writes:

"Everyone will tell you that smooth is fast, but there is one exception. The power-to-braking transition at the beginning of a straight-line braking zone can and should be as abrupt as you can manage. That is how to make a pass stick and it is worth a little bit of lap time, so you want to slam the brakes on at the beginning of every straight braking zone. Of course the brakes had better be warmed up first."

Peter Krause writes:

"Jim Myers, my coach, forced me to move away from being seduced by the sensation of doing something special by "slamming" on the brakes. He refocused my attention towards "squeezing" ON the brakes earlier and, more importantly, focused me on where and how soon I could get OFF the brakes. This reduced my natural tendency to over-brake for the corner and allowed me to become comfortable introducing the slight instability required in order to begin the rotation of the car. This leads to the next phase, how to integrate the end of braking into helping the car to begin turning into the corner."

And Neil Roberts closes his views with:

"Most cars can decelerate harder than they can corner or accelerate. That’s why it takes highly developed skills to avoid braking more than you absolutely have to. As your skills and brake system tuning improve, you will find that you use the brakes harder, but for less time and distance in each braking zone. Mastering the art of deceleration is tough to do, but it is highly satisfying, and it adds to your on-track safety by enhancing your contact avoidance skills."

With all due to respect to Mr. Roberts, I am in Peter's camp on squeezing the brakes, especially during the initial application and modulating them through the whole braking zone and trailing as best as I can.


What say you all? Which technique, in general, do you subscribe to?

[TRAKCAR]

Slamming;

- Hitting the brake with your foot flying through the air on the way down?
- Getting on the brake pedal hard straight into ABS, but no air involved?

Braking is an art, certainly no expert opinion here, but I would think slamming staight into ABS (Without air) can only work in the beginning of a brake zone that is straight and gives you some time for the car to settle as you are starting to trail brake.

Or maybe where a quick stab is needed to scrub of some speed in a straight line...

I'm with Peter Krause, my laptime is mostly about how early I can get off the brake smoothly and on throttle smootly and quickly... If I can plop down the throttle I know I lost the lap.

[bman]

They taught Neil's approach at the Porsche driving school. But I've had more success with Peter's approach. Acutally somewhere in between......

Simple goal for me is to figure out how much speed I can carry into a corner. So on a corner that I am not familar with or struggling, I will brake earlier and lighter feeling my way into the corner. After I've got a sense of the momentun I can carry in, I will work on moving up the intial brake application.

[Dell]

I'd agree more with Neil's approach. I think the problem is the semantics of "slamming" the brakes. Peter's approach does have merit. But the merit is learning where to find the limit is. It is NOT the faster approach. Brake like that and you are going to get passed in every brake zone by the competition.

My approach is to brake as deep as possible and then "slam" on the brakes. The semantics of slamming should be.....get to threshold as quickly as possible.

As has been said, braking is an art and very hard to master. Some people just have a very good feel of the physics of weight transfer, brake threshold, etc..

I have NEVER got into ABS in my car. By understanding what creates the ABS situation you can understand how to take it to the razor thin edge and stay there.

Back to my style. When I slam to threshold I immediately start modulating the brake pressure to keep the stopping right at the threshold (ABS) limit. If you are not at the limit you are not maximizing your brakes and thus not grabbing all those tenths laying around the track. Your goal should be to transition from brake to throttle just after corner entry. This method allows you to maximize front end grip and to TB into the corner which results in the need for LESS steering angle and allows you to get on the throttle sooner. Again, picking up tenths all over the place. I heard a quote from Jackie Stewart once. He said that the brake and throttle were ON/OFF switches working as a single switch. You are either on brake or throttle. Coasting is the enemy of lap times and weight transfer. If there is a time gap between brake and throttle or throttle and brake you are carrying too much speed into the corner or coasting. Not good.

If you ever get to watch an F1 practice live (TV is ok but not nearly as info packed) set yourself up at a high speed straight to tight corner transition. You will think that they all forgot how to drive. Why? They are sliding off the track left and right. Their is a method to their madness. They are trying to find both the perfect brake point for transition to corner entry as well as just how much they can bite off past that perfect spot should they need to "make a move".

The problem I see is most DE guys spend the entire session trying to set personal best times instead of setting sector or turn best times. I set out a goal for a specific sector or turn and work on it at the expense of total lap time. Then data analysis tells me what works and what doesn't. Once you truly understand what works ALL THE WAY AROUND THE TRACK then you can start putting it all together.

This doesn't mean you have to work on a section all the time. Some of the best sessions are had by just running with your buddies!

[FTS]

Dell do you by any chance have data that shows the time frame between coming off throttle and max LongG readings. I'd love to be able to quantify what "slamming the brakes" is.

[TRAKCAR]

+1, I'm taking notes here!

[Dell]

Let me see what I have and post back.

[csmarx]

I'm with Peter Krause. From memory it was Sir Stirling Moss who said that the hardest thing he had to learn in racing was how to take his foot of the brake. Focusing on that certainly helped me improve lap times when I was stuck in a rut. But with the caveat that once you figure out how to take the foot off, then you can start focusing on how to engage the brake - i.e. later and harder.

Early on I used to focus more on the foot-on part, but to the detriment of my corner entry and speed. Through data analysis I finally figured out that's were I was loosing speed vs. my co-drivers.

I haven't driven much for the last 5 years, so now I'm back to developing my sensitivity to the foot-off transition.

-Christian

[FTS]

I have to admit, my weakest point is how and when I come off the brakes, for the past 6 years I have been improving, but that is still the one biggest issue I have.

[Gator Bite]

Here's another opinion, from Vic Elfords 'Porsche High Performance Driving Handbook':

"In the last chapter we saw how important smoothness is in accelerating. If anything, smoothness is even more important when it comes to braking at the limit......."

Then later,

"Although I have emphasized the importance of smoothness, here is one time when you need an abrupt little stab or jab. When your foot goes to the brake pedal the first moment should be just that - a little jab at about 4 on the scale above.

That little jab will take up the pressure in the braking system and cause an instant weight transfer toward the front wheels. As soon as that's done you can start squeezing on the pedal in earnest."

[landjet]

I've only been doing DE's for 4 years so I'm no expert. I do know that when I began I would slam on my brakes and brake more than I had to. One of my instructors worked with me on braking and got me to squeeze on the brake pedal firmly at the beginning of the brake zone and to ease out of heavy braking in order to concentrate on carrying more speed into the corner entry.

One thing I have learned about driving, it's like an onion. As you progress and get a feel for a skill, you peel a layer of experience off, and that reveals the next layer that you must concentrate on to master.

[24Chromium]

I was always taught, and in turn taught my students, that the best way to apply the brakes (in a straight braking zone) was to squeeze them at first in order to get the car to squat for best stability, then hammer them to threshold, gently easing off as you transition to throttle. The trick is to do all this in the least possible amount of time. I've yet to feel I've truly mastered this technique in my 15 years of DE driving!

[csmarx]

Here is a theory:

I've recently perused a PDF about the physics of racing, and while it gets a little too involved in the equations for my (MIT educated) brain, it does have some interesting conclusions and corollaries. For example in the chapter on why smoothness is important, we learn that given the car and it's suspension is really a spring/mass/damper system it likes sinusoidal inputs.

Hmm, I've always known that smoothness is important, but I never really thought that smooth doesn't necessarily mean linear! So I've been experimenting with doing sinusoidal-ish steering inputs, i.e. start of slowly and then accelerate the input to quite quick and slowing it down again as I reach full lock. Its quite amazing. If you have a heavier car with a soft suspension try this. With my wife's Prius if I do simple linear input going somewhat swiftly into a turn, it leans out of the turn and almost feels like it's going to topple over - despite being smooth about it. If I try the sinusoidal input instead, it's completely different! It kind of squats down, almost leans into the turn and is far more stable. Wow!

I have yet to try this on track, but I image that the GT3's relatively stiff suspension and stiffer low profile tires will make the effect less noticeable. It'll be interesting to see.

Now back to our regularly scheduled programming.

I'm wondering if braking isn't the same thing. It would certainly explain variations on the theme that one should start by a softer application of the brakes to get the car to settle before squeezing harder. Similarly the idea of getting off the brakes in a more gentle fashion after a hard application. In fact if you combine these two you get: first soft on, then hard, then soft off. It's basically sinusoidal!

Something to ponder.

-Christian

[FTS]

Good points Christian. Although I understand your points, IMO "smoothness" is not being smooth with your inputs but with the resultant behaviour of the car. Most pro drivers we see driving seem to have very jerky steering and other inputs, but as long as their actions result in smooth weight transfer through out the car, that is all that matters.

[beez]

It depends on what kind of corner it is, but in every instance, your first hit on the brakes should be your hardest, then you modulate as necessary. For tight corners being approached at high speed, that initial hit might be 80-90% or even all the way to threshold... for sweepers, this initial hit might be 25-30% or even just a brush, and longer duration. There are other factors that come into play as far as how much braking is needed - going uphill? Less braking is needed than you might think... long sweeper? The friction of the tires being being turned for that long of a time will help slow the car down, so don't over-slow the car on entry... I see a lot of people over-slowing their car for sweepers. BTW, threshold is not getting into the ABS, it's just short of it - without ABS, it's just short of lock-up.

But, the most important thing is you want to scrub-off speed of the mass of the car, but not kill your momentum doing so. In all cases, you want to use the modulation of the brakes to get the car settled back down onto the rear axle some - a good 10 feet or so - before turn in, so the car is balanced when you begin to turn the wheel for the corner. So many people concentrate on very late braking and corner entry speed, with most of the car's weight still on its nose as they turn in, which kills momentum. I see and coach many very late brakers who find themselves "parked" in the turn, having broken their momentum with this style of driving. Having the car more balanced at turn-in allows you to use super-light braking for balance, or trail-braking for rotation on the way to the apex, and a balanced car at the apex allows you to carry momentum through the corner, and get on the gas sooner as you exit. You can't get on the throttle early with a poorly balanced car. It's corner exit speed, not entrance speed, that makes the difference in gaining those tenths that are laying around the track waiting to be taken. The sensation of entering a corner fast can fool you into thinking you're making up time there, but you can only carry so much speed through the apex of any turn.

I guess I subscribe to slightly longer, and slightly earlier braking to keep the car more balanced. I used to be - as one of my coaches called it - a "scary late" braker, but I'm much faster doing it this way. My mantra: It's not how fast you go, but how little you slow down.