Trail Braking for Beginers

[72SMFI]

Can someone explain to me the General Idea about trail braking. I was trying left foot braking today on a windy road. I now have enough left foot control and now need to apply it correctly.I think I need to go buy
Vik Elfords book but for now lets post some stuff about it on the board. PS I bet I am not the only driver here "or at least dont think I am"driver here that knows how to trail brake correctly. So lets keep it simple and go from there. Thanks

[JSDSKI]

Trail braking can be done with left foot, but is not necessary - it can be done with either foot (or both in a really bad situation!)
Essentially you brake hard, usually in a straight line, before turn in begins and then modulate the pedal softer as the car starts to turn. So, on the brakes hard and then "trail off" as you start to turn. This is used to improve front end grip by increasing pressure on the front tires vs the rear, and to reduce understeer.

If the maximum force the tire uses is 100% whether accelerating, braking, or turning, then any combination of forces equals 100%. Brake hard in a straight line (100%), brake pressure trails off (70%) - then you have 30% for turning forces... at least that's how I think about it....

[Efrain68912]

As I understand it (and how I practice it), trail braking is carrying your braking past the end of the turn in point for a corner. Between the turn in point, and, lets say, the apex, the braking pressure is gradually decreased until there is none at all.

I use it to carry more entry speed and help rotate the car.

[ChrisBennet]

When I trail brake into the corner, I've got my right foot on the brake and the gas (heel toe) already. I keep my foot in that position past the turn in and reduce brake pressure gradually to zero and "roll" my foot over on the gas at some point before the apex.

The obvious advantage to trail braking, is that you can brake a little later. Less obvious is added front grip that JSDSKI's great description mentioned.

If you do all your braking in a straight line, when you get off the brakes, the front of the car will come up/be unweighted and have less traction just at the point where you are trying to turn in.
By trail braking, you keep some weight on the front and as the corner forces start pushing the nose down you can release the brake pressure and the nose stays down/keeps gripping.

I believe Jackie Stewart said that how you released the brakes is more important than how you press them.

-Chris

[89911]

Straight line braking=all braking done before turn.
Trailbraking=turning before staight line braking is completed.

How much turning and braking is an endlous variable and is defined by factors such as speed before turning, the type of turn your coming into, tires, weather, brakes, etc, etc, etc. What is does, basically, for rear engine cars is get the backend around quicker to get you into a better position for the next turn or series of turns. At least for my car, I can trailbrake and then use the throttle to regain traction. It a delicate balance that usually can be only done on tracks that you have a series of repeated attempts to find this point. Not recommended for the unknown curve ahead or any unfamiliarity with the handling of your car.

[Jack Olsen]

I haven't yet learned to trail brake effectively, although I frequently do it in the way it's being described here, which is sort of an extension of heel-and-toeing in a way that allows you to come 'hotter' into turns.

I think you would have to use your left foot for it in track situations, where it's asking a lot to both be full on the throttle before an apex (as in, say turns 1 and 2 at Willow Springs) and also using the left half of your right foot to modulate the braking. Especially in a sweeper like turn 2 at Willow, where my guess is you could use trail braking to stabilize the car in the first half of the turn, just as you use the throttle to plant and point it in the second half.

But I'd be interested in opinions from people who have driven this track. I could be way off base on this.

[JSDSKI]

I should add - maybe I wasn't clear on this - that trail braking is really a method of brake use. Almost a style. Bondurant is very big on trail braking. J. Russell School technique is almost all straight line braking only. You can use your right foot, left foot, with or without heel and toe, etc - it is, as Chris (thanks for the kind comment) points out, quoting Stewart, "how you release the brake".... retaining momentum and smooth transitions are everything in fast driving - most of Stewart's comments about driving are usually related to smooth transitions.

Jack, your logic makes sense - it sounds like left foot braking would be smoother and easier to modulate than heel and toe in that situation.

[stuartj]

Left foot and trail braking- this is a subject near and dear to my heart. Having had previous instruction from 3 of AUS’s professional touring car drivers, and numerous other instructors, I had noticed that the really good guys do not left foot and rarely trail brake (in my 911 at least), using the throttle to balance the car instead.

Recently, the SO (god bless her) gave me a days one on one instruction with a one of AUS’s touring car pro’s, and I was keen to quiz him on weight transfer and trail braking to load up the outside front on turn in. His view (he’s owned many Porkers and currently a Boxster S) - a 911 is not a trail brake car. (think about that) The key is get the car balanced and where you want it, then get on the power harder and earlier, and get the weight over the back. Once the arse is hunkered down and under power, there’s little you can do to upset a 911, obviously depending on the power and traction available. (Most 911 drivers would agree that its weight transfer associated with entering a corner too fast that gets you into strife.)

Another observation- having been taught and a being big believer in left foot braking when not gear changing, and there usually points on any track where this is the case, its interesting that NONE of these pros (so far anyway) left foot brake. This most recent instructor, who also drives a two pedal Modena in our production series, told me he does not left foot that car or his V8 touring car. In fact, with all these guys, it’s the absence of fancy stuff that stands out. Like watching Tiger Woods swing, it looks so easy and balanced, he’s not doing any thing fancy, just doing everything right….

Lesson for me, stick to basics, brake harder, concentrate on balance and line, more power earlier, use more revs.…

Just my 3.87 cents….

[89911]

Jack, when I did Skip Barber at Laguna Seca last spring, we spent a day learning to trail brake coming down the hill into Andretti's turn. What then wanted us to do was to come into the corner so hot that you were on the verge of spining the car. Hard to do in these little cars that can hold 1.2 G's. But coming into a long straight and hitting such a tight turn, it is the best way to come out of there with the most amount of exit speed, your ultimate goal. This was opposed to coming down the hill, braking completely, turning and then accerating. Chances are your doing it and not even knowing it. It was an excellent test and very demanding. Each time you thought you did it right, they radioed to you to go faster. Humbling indeed. Picture below is someone who managed to lose it.

[jluetjen]

I believe that Trail Braking is definitely one of those "Horses for Courses" sort of things. It's very useful in some situations and less then helpful in others. I agree with the points made above (The Traction Circle, the criticality of the release and the concept of managing the balance of traction front and rear by using the brake and gas) so I'm not going to say more. A couple of other observations which I've made on the subject:

1) I've come to the conclusion that trail braking is one of those things which has to be unlearned while a novice and then relearned as you get better. Being the latest braker will rarely make for a fast lap. The important thing is to learn how to carry as much speed as possible through the corner -- especially the entry into the apex. Generally novices over-brake for corners since they don't have a clue how fast a car can really travel though a given corner. So worrying about trail braking when you are a novice will often make your laps slower not faster. I think that this was Skip Barber's point in the above example. Think about it: More time on the brakes, less time on the gas just can't equal a faster lap.

2) Speaking of Skip Barber, when I took their class at Lime Rock they definitely steered students away from trail braking for the first couple of days. I think that this was for two reasons, the first I mentioned in point 1. The second reason is that since we were using FF cars, they are naturally very direct and "twitchy". Novices generally don't have the reactions nor the experience to manage the sudden oversteer that results from too much trailing throttle oversteer. So first we had to learn to "walk" (and threshold brake in a straight line) before we could "run" and trail brake. Put simply: K-I-S-S.

3) Speaking of Lime Rock, I think that Big Bend at Lime Rock is one of the classic trail braking corners - of which there are few. Since it occurs at the end of the longest straight, is a long 180 degree corner which exits onto a short straight into the S's. In this situation, exit speed is not critical, but carrying top speed down the front straight is. Not to mention the corner is so long that there is a long time spent balancing the throttle. The result is that the corner rewards carrying the braking zone deep into the entry of the corner. I suspect that the corner at the end of the back straight at Mid- Ohio (going into Madness?) is similar in this regard, but I've never driven there. Many tracks don't have corners like this.

4) Another point made at Skip Barber is that many people use trail braking as a crutch. Novices often get nervous and take too early of an apex on corners. When they get the car to the apex, they use trail braking to rotate the car so that it is positioned for the exit. This is often when they will spin. Remember the video of the Subaru rolling at Lime Rock's climbing turn. It spun because he TTO'd (which is less drastic then Trail Braking) after taking an entry to the corner. Usually the fastest turn-in point and apex are a lot later then most people think they are. If you are doing it right, in most corners you won't need to trail brake and you will be carrying a heck of a lot more speed then someone who does. Picture making up 50-100 yards in one corner alone! That is how drastically different the cornering speeds are.

5) Trail Braking will often depend on the car and its set-up. Porsches with their rear weight bias will often reward it (for the reason mentioned by others above) while punishing its abuse with a spin. Stock Cars (as well as I suspect AUSCARS and most Touring cars) have most of their weight already on the front. So trailbraking will put more weight on the already overworked front tires which sounds to me like a recipe for understeer.

6) Finally, for every rule there is an exception. If everyone around you is trail braking into a corner, you might want to consider NOT trailbraking. Try taking a wider entry and a later apex with more time spent on the gas. You may find that the rest of the field is outbraking itself and you can pass them on the gas.

[efhughes3]

I've got a related question on braking. Can someone explain how heel & toe works? I've got the idea of why you'd want to do it (not having a third foot-at least most earthlings I know), but HOW do you do it? I've tried to do it sitting in the garage, but it seems like there is too much of a difference in distance from me to the brake pedal and me to the gas pedal. It's tough to span both of these pedals at the same time with my heel on one, and my toes on the other. Maybe I'm taking the name of the concept too literally.

[Randy W]

I use trail braking when I want to "point" the 911, and throttle steering the car isn't an option. As many have already noted it should be used judicously and not used as a crutch for braking too late or having the wrong line. I've been to Bondurant, and it's a great place to learn this technique - which can be refined forever. Stuart's explaination was a great counterpoint. "Less brake, more gas" works well in a 911, as long as you don't carry too much speed coming into the corner. I think smoothness on first application of the brakes is almost as important as when coming off them, but I'm no Jackie Stewart. It is interesting to note that the majority of Touring car drivers do not left foot brake, and the majority of rally and National level autocrossers do left foot brake. I think this has more to do with the structure of the courses they run on, primarily - speed, traction and tightness.

[ChrisBennet]

Originally posted by efhughes3
I've got a related question on braking. Can someone explain how heel & toe works? I've got the idea of why you'd want to do it (not having a third foot-at least most earthlings I know), but HOW do you do it? I've tried to do it sitting in the garage, but it seems like there is too much of a difference in distance from me to the brake pedal and me to the gas pedal. It's tough to span both of these pedals at the same time with my heel on one, and my toes on the other. Maybe I'm taking the name of the concept too literally.

It is hard to heel-toe in a 911. Ideally, you'd press the brake with the part of your foot near your big toe and use the part of your foot near your little toe to press the gas by rolling your foot over on the gas. This doesn't work too well in a 911 because the gas is too far away (from the brake. Instead, you must use the heel of your foot on the gas near the bottom of the gas pedal. Because a small movement at the bottom of the gas pedal results in large throttle change, it is harder to regulate the amount of throttle using this method. What I wound up doing is more of a stab on the throttle with my heel.
The pedals are too far apart side to side but some complain that the pedal heights are too far apart up and down as well. I haven't found this to be the case. They line up OK when you are braking hard like you do at the track. I don't see how anyone can practice heel toeing on the street.
In my case, I had a wider gas pedal made and that improved things for me.
-Chris

[ChrisBennet]

Originally posted by efhughes3
I've got a related question on braking. Can someone explain how heel & toe works? I've got the idea of why you'd want to do it (not having a third foot-at least most earthlings I know), but HOW do you do it? I've tried to do it sitting in the garage, but it seems like there is too much of a difference in distance from me to the brake pedal and me to the gas pedal. It's tough to span both of these pedals at the same time with my heel on one, and my toes on the other. Maybe I'm taking the name of the concept too literally.

It is hard to do in a 911. Ideally, you'd press the brake with the part of your foot near your big toe and use the part of your foot near your little toe to press the gas by rolling your foot over on the gas. This doesn't work too well in a 911 because the gas is too far away (side to side) from the brake. Instead, you must use the heel of your foot on the gas near the bottom of the gas pedal. Because a small movement at the bottom of the gas pedal results in large throttle change, it is harder to regulate the amount of throttle using this method. What I wound up doing is more of a stab on the throttle with my heel.
The pedals are too far apart side to side but some complain that the pedal heights are too far apart up and down as well. I haven't found this to be the case. They line up OK when you are braking hard like you do at the track. I don't see how anyone can practice heel toeing on the street.
In my case, I had a wider gas pedal made and that improved thing for me.
-Chris

[Vipergrün]

I had heard that with our cars we should brake straight line, hard and late if possible, then get back on the throttle a bit at the turn in to settle the suspension. Is that correct? Hard to do any of this on the street time for some track time.

[jpachard]

A big key in trailbraking a 911 is a limited slip. The Porsche ones that have lockup on deacceleration really help in this situation by keeping the back end of the car in line. As jluetjen mentoned earlier, Limrock's big bend is a classic example. I cut about a second off my time there by using this technique and in fact our region now teaches this in higher run groups. As a result I am not a crazy hard braker now and the car feels much more settled at the entry.

Cheers, James

[CJFusco]

This is a wonderful post... it's times like these that I love Pelican.

[cstreit]

My 2 cents worth here:

Trailbraking is effective on certain corners but I personally don't feel like it's an overall go-fast remedy. Additionally the margin for driver error gets much lower when using it, and unless you can guarantee success, better leave that trick in the bag unless you have nothing to lose. THe time you add to a lap in ONE mistake is much more than you reduce through trail braking in an average race...

That being said, there are a few corners where I use it. Specifically those corners which cause my car to understeer to the point where effective turn in, or track out, becomes so difficult that proper entry and exit speeds are hindered. For example, short diminishing radius curves where it's difficult to make a high speed exit are good candidates for me.

So I approach these corners a bit quicker than I "should" and as I brake for them, brake a little easier and "trail" off the brake as I'm turning in... This rotates the car a bit more than my speed would normally allow. End result is I went into the corner faster, got the car turned in a little faster and more towards the apex, then was able to exit faster because at my turn in (because of trail braking) my speed was actually lower than normal so I get a good long shot through the exit....

Does it REALLY work for me? I dunno, but it feels better than tip-toeing through the dimishing radius.

Your mileage may vary, batteries not included...

[930fan]

For me, trail braking is a technique used for cars with problems turning into corners and I find it crucial (especially in slow corners) for my front wheel drive race car as it helps "point" the car and set it up for the exit. I had to unlearn it in a hurry when I was driving the 930 as it just encouraged the back end to get really lose and this is unnerving to say the least.

I've sat with a couple of pros too and like StuartJ, I've found that they tend to shy away from TBraking and LF Braking and concentrate on plain old slow in fast out.

[Don Wohlfarth]

Stuart's post is without doubt one of the best answers on PP in a long time.
Trail braking is simply helping the car rotate into the turn. It is a minor tool for the driver.
Most experienced drivers will seldom use trail braking on a road course with the exception of possibly 1 or more unlikely 2 turns. The risk far outweights the rewards. Its use will depend on what you are trying to get your car to do, type of turn, and entry speed.
You ususally only use trail braking on turns 65-70 mph or less as the amount of braking in the turn is hard to modulate in a 911 because of the weight bias and you are forcing that extra weight in the back to go in a different arc (causing rotation of the car) and you have to control that weight transfer by slowing it down, stopping it, and then go in another direction, all in less than
[b]1/2 second[b/].
Briefly and trying to keep it simple, when a car is traveling 60mph it is moving 88 feet per second. The rotation of the car will take place over 10-20 feet. Your time span is very small.
A drivers track time is better spent on concentrating on braking points, turn in, apex, and track out, on a consistent lap after lap basis and learning to be smooth than he will ever gain from learning to trail brake.
Randy, ax'ers sometimes use the left foot to brake because they are using the right foot to accelerate at the same time. A driver can better modulate the input on brake with one foot and gas with the other and helps with transition. They can't left foot brake at every turn as they sometimes have to use the clutch.