Trail Braking?

[ROB IS THE STIG]

Hey guys, could someone please explain the concept of Trail Braking??

Im a little confused.

Many thx

[PTRACER]

The "standard" way of braking is to brake in a straight line as you approach the corner, release the brakes, turn in and head towards the apex, gradually applying the throttle.

Trail braking is where you begin to brake in a straight line, but continue braking after turning in, gradually release them, but not coming off them until you've pretty much reached the apex.

[tristancliffe]

Your tyres (each and collectively) can supply a certain amount of cornering force and a certain amount of accelerative thrust, but can not supply all of both at the same time.

If you search for traction circle you'll probably find a graphic that explains that in a straight line you can accelerate/brake fully, and whilst turning really hard you can't accelerate/brake - if you try you 'go outside' the circle and lose grip. If you are cornering at half of your potential then you can accelerate at half your potential...

Straight line braking is very inefficient, because you are not using all of your potential at any given moment, and you are therefore losing out to someone who does. Trail braking is a way of gradually easing off the brakes as you start to turn in so that at all times (in theory!) you are using all the grip you have. It's the exact opposite of gradually getting on the power before you are going in a straight line; nobody in their right mind would turn, wait until they are going totally straight and then get on the throttle!

The greater your skill, the closer you can ride the edge of the traction circle (actually, an ellipse, but best to ignore that for this explanation!).

Some cars, and some corners are not ideally suited to much, if any, trail braking, but they are the exception. Pretty much all of the time you HAVE to brake into the turn, and as soon as you are off the brakes completely you need to be feeding in the power. If at any point you are not on either the throttle or the brake then someone else will be faster than you.

Hope that sort of helps.

[Tim Falce]

Originally Posted by tristancliffe

Straight line braking is very inefficient, because you are not using all of your potential at any given moment, and you are therefore losing out to someone who does. Trail braking is a way of gradually easing off the brakes as you start to turn in so that at all times (in theory!) you are using all the grip you have. It's the exact opposite of gradually getting on the power before you are going in a straight line; nobody in their right mind would turn, wait until they are going totally straight and then get on the throttle!

The greater your skill, the closer you can ride the edge of the traction circle (actually, an ellipse, but best to ignore that for this explanation!).

Some cars, and some corners are not ideally suited to much, if any, trail braking, but they are the exception. Pretty much all of the time you HAVE to brake into the turn, and as soon as you are off the brakes completely you need to be feeding in the power. If at any point you are not on either the throttle or the brake then someone else will be faster than you.

Hope that sort of helps.

Not really, my car and my buttocks don't do well on trail braking so what's better, a car that's accelerating from the turn up to the apex whilst the other car is still braking to the apex?

[ROB IS THE STIG]

It takes some practising by the sound of it, if done well does it gain u much time/speed out of corners?

[PTRACER]

Trail braking can really help turn in, especially in an understeering car, because it keeps the weight at the front over the front wheels. It can also cause oversteer though so it doesn't suit every car and every driver.

[terence]

Much more effective if your car happens to have ABS fitted,in which case it can be very usefull,I think you will find that you will be better off doing it all in a straight line and let those who are attempting trail braking just slither off down the inside of you,you will have the advantage in that your braking is over and done with.Next time your at somewhere like Snetterton,watch some racing from Russell,you'll soon see what happens with the late braking heros.

[tristancliffe]

Originally Posted by falcemob

Not really, my car and my buttocks don't do well on trail braking so what's better, a car that's accelerating from the turn up to the apex whilst the other car is still braking to the apex?

a) car is accelerating on the throttle from the 'turn up to the apex' (do you mean turn in?)?

b) car is braking to the apex and then accelerating.

In general, car b will be quicker (although of course some corners require you to be on the power before or after the apex, but we're generalising here), because car a will be that much slower at turn in to be able to accelerate all the way through the corner.

The cars that tend to trail brake the least are the really really stiff ones, where braking and turning would tend to lock a wheel (or require a marked reduction in braking torque), causing more loss of time than simply braking in a straight line. The softer the car the more, in general, trail braking is required and tolerated.

Trail braking is not the same as braking too late! Braking in a straight line is the same as braking too early. Watch at Russells and see how many people are on the first apex kerb as they come off the brakes - they have trailbraked into the corner. Most people probably do it without realising, because it's not natural to brake in a straight line and remove your foot from the pedal before you move the steering wheel. Nobody has ever been quick like that. Ever.

[terence]

I wonder if Sir Jackie Stewart/Martin Brundle et al realise this. I was not implying that trail and late are related,just that people tend to take the brake release point up to the appex/clip point,therefore being on the brakes longer.As for braking in a straight line,different techniques then!

[Tim Falce]

Originally Posted by tristancliffe

a) car is accelerating on the throttle from the 'turn up to the apex' (do you mean turn in?)?

Yes

[GORDON STREETER]

Very often I will trail brake when trying an alternate line overtaking into a corner.
You will find it easier to control the car if you left foot brake and balance it on the throttle. Its not the easiest thing to learn but it does pay dividends.
I even left foot brake on the road and have done for years, to get the "feel" in the pedal is the "alien" thing and its best to practice it in an automatic if you have the chance.

[ROB IS THE STIG]

Originally Posted by GORDON STREETER

Very often I will trail brake when trying an alternate line overtaking into a corner.
You will find it easier to control the car if you left foot brake and balance it on the throttle. Its not the easiest thing to learn but it does pay dividends.
I even left foot brake on the road and have done for years, to get the "feel" in the pedal is the "alien" thing and its best to practice it in an automatic if you have the chance.

yeah, left foot braking is not easy to practice, head vs steering wheel is a distinct possibility!

[RF_Racer]

Originally Posted by tristancliffe

a) car is accelerating on the throttle from the 'turn up to the apex' (do you mean turn in?)?

b) car is braking to the apex and then accelerating.

In general, car b will be quicker (although of course some corners require you to be on the power before or after the apex, but we're generalising here), because car a will be that much slower at turn in to be able to accelerate all the way through the corner.

The cars that tend to trail brake the least are the really really stiff ones, where braking and turning would tend to lock a wheel (or require a marked reduction in braking torque), causing more loss of time than simply braking in a straight line. The softer the car the more, in general, trail braking is required and tolerated.

Trail braking is not the same as braking too late! Braking in a straight line is the same as braking too early. Watch at Russells and see how many people are on the first apex kerb as they come off the brakes - they have trailbraked into the corner. Most people probably do it without realising, because it's not natural to brake in a straight line and remove your foot from the pedal before you move the steering wheel. Nobody has ever been quick like that. Ever.

I would disagree, I read an article by Peter Windsor who has on several instances analysed F1 divers. Schumacher always had a stiff setup, to an extent so did Mansell, they both prefered a a darty car. There two are the well known driver who trail brake. Prost is another who was very good at trail braking.

Trail braking usually goes together with an early turn it style (ie, schumacher, Mansell and Prost), it allow the driver to get to the apex faster. Then some drivers are able to rotate the car on the apex and power back out so in effect its a fast in and fast out approach... conventional wisdom says slow in fast out is the best way.. may be, but if you can do the fast in and fast out you clearly have an advantage.

[mountainstar]

Originally Posted by PTRACER

Trail braking can really help turn in, especially in an understeering car, because it keeps the weight at the front over the front wheels. It can also cause oversteer though so it doesn't suit every car and every driver.

The main key is making sure enough grip is given to the tires to turn. All depends on the car, but trying to find that balance can be hard at first, especially in a road car with road tires on track. And it all depends on the corner as well.

If you watch me do it, I'm threshold braking and as i track in and start adding steering I am gradually releasing brake pressure all the way up to the apex. By the time I hit the apex my foot has moved over to the throttle and I am feeding in the power as much as I sense I can to the track out point and by the time my wheels are straight I should be pretty much at 100% throttle. I'm considered by others to be very smooth and riding with me you wont feel any abrupt weight transfers all over the place.

With newbies I tend to advocate later apexes, braking in a straight line, slow in fast out. And for the people and training I do that is more applicable anyways. We are looking for solid but quick driving and the extra 10ths less important than keeping the vehicle intact and surviving. Still if mostly braking in a straight line, you need to trail out of the brakes smoothly, not just jump right off the pedal.

A lot of the Billys that have been playing too many video games are 100%ers in that with all three control inputs everything is 100%. It's either 100% gas, 100% brakes or 100% steering. To be quick I think you've got to be able to manage the control inputs smoothly to allow the car to transition from point to point. In other words perhaps managing the weight transfers in the car smoothly.

I've done a lot of schools down under and a lot of the coaching I've got down there, they are not big on trail braking especially with the big V8's. Basically they get the big ******* slowed down in a straight line, trail off quickly as they track in, apex, get it pointed at the track out point and feed in the power quickly. A lot of the tracks in NZ and Aus aren't very technical either.

In driving instruction there is no perfect right way that suits every car and every corner, so a lot of it is learning different skills and perspectives and then trying out what works for you and your car and the track you are on.

That's my take anyways.

[mountainstar]

Originally Posted by RF_Racer

I would disagree, I read an article by Peter Windsor who has on several instances analysed F1 divers. Schumacher always had a stiff setup, to an extent so did Mansell, they both prefered a a darty car. There two are the well known driver who trail brake. Prost is another who was very good at trail braking.

Trail braking usually goes together with an early turn it style (ie, schumacher, Mansell and Prost), it allow the driver to get to the apex faster. Then some drivers are able to rotate the car on the apex and power back out so in effect its a fast in and fast out approach... conventional wisdom says slow in fast out is the best way.. may be, but if you can do the fast in and fast out you clearly have an advantage.

Wouldn't argue with that, except that F1 cars can pull 5G's in corners and have oodles of grip. Probably for most people here they are driving the equivalent of a Piper Cub airplane while the F1 guys are in Eurofighter Typhoons.

It comes down the what level of grip the car and tires have and finding how much those 100 units of grip are worth. That's why I like skidpads.

[terence]

One further point is that just jumping off the brake can sometimes allow the car to accelerate,far better to just ease off the pedal.

[GORDON STREETER]

Originally Posted by terence bower

One further point is that just jumping off the brake can sometimes allow the car to accelerate,far better to just ease off the pedal.

I never thought of that Terry (perhaps thats why I left foot brake )

[tristancliffe]

Originally Posted by RF_Racer

I would disagree, I read an article by Peter Windsor who has on several instances analysed F1 divers. Schumacher always had a stiff setup, to an extent so did Mansell, they both prefered a a darty car. There two are the well known driver who trail brake. Prost is another who was very good at trail braking.

Trail braking usually goes together with an early turn it style (ie, schumacher, Mansell and Prost), it allow the driver to get to the apex faster. Then some drivers are able to rotate the car on the apex and power back out so in effect its a fast in and fast out approach... conventional wisdom says slow in fast out is the best way.. may be, but if you can do the fast in and fast out you clearly have an advantage.

At the superstar level of talent in the F1 level of vehicle ability then exceptions are going to become the norm!

[midgetman]

Originally Posted by terence bower

One further point is that just jumping off the brake can sometimes allow the car to accelerate,far better to just ease off the pedal.

Sitting alongside people while teaching in the skid car, I've seen that happen many times. It's what's wrong with the DSA's "driving by numbers" approach.

Fascinating discussion, I didn't realise that what I do naturally was trail braking.

I've always found the "brake/off/turn/straighten/accelerate" method is best for teaching, people can blend it together as they develop their style. It also pays dividends in the wet, stops the Billies putting the power down too soon.

[ROB IS THE STIG]

Thank u all, very informative as always.

Appreciate it.

[GORDON STREETER]

I have always likened the throttle and brake as "loud and soft" pedals like a piano, and having a dog box you can get away without using the clutch.

[grantp]

Originally Posted by GORDON STREETER

I have always likened the throttle and brake as "loud and soft" pedals like a piano, and having a dog box you can get away without using the clutch.

Used to have a bog standard road Sierra that did not enforce clutch use to make progress. Heel and toe to get the revs about right was usually enough.

Although I always left foot brake in an Auto I never felt the brain reprogramming would be a good idea when driving a manual. The risk of flipping into the use of the 'clutch' when driving an auto or braking with the clutch when driving a manual was too great. No problem using either method as long as I keep them separate according to transmission type!

Trail braking in an auto is a natural evolution from driving up to roundabouts. So many require a change of direction as one approaches the line that braking and steering at the same time are to be expected. This then becomes natural.

The downside on a track day in a fairly modern car is that all the stability control systems also use the brakes so they can get very hot indeed. This shows up a second benefit in that you get a little more brake time in the bend if any fading makes you too fast for comfort on the approach to turn into the bend. I suspect my current Saab would make the bend anyway since it seems to run on invisible rails but the worry is always that one finds a slow Caterfield on the apex when committed to the corner in a fashion that prpobably precludes attempted braking - given that the brakes are already overheating!

[Austinspace75]

At all levels of motor racing, I'd see the use of trail braking as a highly subjective question. Trail braking is just one tool (from many) that a driver can employ depending on what he's finding and what he's driving. What'll work in one situation won't necessarily work in the next... If only it was so simple.

For example, on the Silverstone National circuit, I get the best lap time out of my Astra if I use a short, deliberately violent stab on the brakes at Copse to get the back end light, induce over-rotation and get the whole car pointing directly at the Apex all in one action at turn in. It all happens long before I reach the apex, but you could deduce that I'm employing some trail braking as I'm not braking in a straight line. In contrast, when I get to Becketts, the last thing that works for me in that car is the same approach... what's needed there is a longer steadier brake down through the gears keeping the car settled before carefully turning in for a long apex to ensure a clean acceleration out onto the straight. I can't throw the car into the corner in same way as I do at Stowe because the brakes just don't have the power for it and I can't brake all the way to the apex as the front left tyre wouldn't last five laps. The best way at that corner is the classic 'text book' approach.

The friction circle is a very useful way of graphically explaining what a tyre could do for you... but that's all. There is alot more to the story (which is why so many millions of man hours are spent studying and developing ways to maximise it). The ability to transition from one extreme to the next is highly dependent on the car and corner in question.

In a 911, the driver is often required to trail brake not just to attempt a perfect transition from braking to cornering, but to enable cornering to happen in the first place! - Due to the location of the engine, the front end needs weight in order to turn in properly and this is best acheived by keeping the brakes applied during the turn in stage. With this in mind, imagine the opposite situation.. and then all the many subtle shades between the two.... not to mention gradient and camber...

[dtype38]

Originally Posted by tristancliffe

......Straight line braking is very inefficient, because you are not using all of your potential at any given moment, and you are therefore losing out to someone who does........

Hmmmm... funny old world when someone states as fact something that simply isn't true. Well, let's qualify that as "only true in some cases". You see although I know perfectly well how to trail brake, but I don't use it much. Lap times have proved to me that nearly all race tracks are slower using trail braking. The reason is simple - I can carry more turn in speed with the car neutral than with it loaded at the front. I would suggest that's because the the front outer tyre friction circle is dominant. I can also carry more apex speed with the car loaded up at the back than with it neutral. This may be because it unloades the front inner tyre thus helping me to ride the kerb more easliy, but I'm open to offers on that one. Anyway, whatever the technicalities, when you're giving away horsepower to the opposition, you need to arrive at every apex with your right foot already planted on the floor for the next straight, not just getting back on it!

[Austinspace75]

Yep, I'd concur with all you've said there... and find myself doing the same thing - possibly because the battle I have to keep the front end in line is best won by using the rear end as much as possible!

Anyway, regarding straight line braking, its by far the most efficient way to scrub off speed because you are using all of your potential.... you're just using it all for braking that's all (as long as you're braking to the threshold of course).