Trail Braking

ScoobyChris · 20-04-2007, 09:34

What is trail braking? In essence, it means continuing to brake after having turned in for a corner. The further you progress into the corner, the more you turn the steering wheel and the more pressure you release from the brake pedal. Typically, the procedure goes like this:

-You are hurtling in a straight line toward a corner;
-You apply the brakes - fully - while still traveling in a straight line;
-At some point, you release a little pressure from the brakes and start to turn in;
-As you bend into the corner and approach the throttle application point, you progressively release the rest of the pressure from the brake.

What's the point of it? Trail braking helps you rotate the car into a corner by controlling the transfer of weight onto the front tyres, giving them more stick, and thus compensating for any understeering tendency the car would otherwise have.

The alternative is: do all of your braking in a straight line, then release the brakes entirely, then turn in. The trouble with this technique is that when you release the brakes, weight - and therefore stick - will be removed from the front tires, just when you need them to be loaded enough to turn the car into the corner. So - unless the car is set up to be driven like this - it will understeer away from the corner. This is typical behavior for 'street' (aka massively understeering) cars that have been adapted for racing.

On the other hand, a 'proper' race car will probably oversteer if you don't trail brake. If you turn into a corner with your feet off both brake and throttle, the front tires will have all their traction budget available for turning while the back wheels will be doing some (engine) braking. Net result: oversteer. Application of the brakes settles down the oversteer by substituting a proportionately balanced loss of steering traction (because the brakes are biased towards the front). In fact, you use the brake pressure to control the rate at which the car rotates into the corner.

How much trail braking you do at a particular corner - i.e. what percentage of the corner is taken under braking - depends on the angle of the corner. For a 60° corner, you'd typically only trail for a few percent of the corner, for a 90° corner, you'd typically trail brake for maybe 25% of the corner, and for a bigger corner, you could do it for up to 50% of the corner. You are aiming to trail off the brakes until they are released completely at or before the throttle application point (which typically occurs somewhere before the geometric apex).

Another way of looking at trail braking is: what you're doing is braking so late for a corner, that you're never going to make it if you carry on in a straight line. In order just to stay on the track, you have to release a little of the pressure on the brake pedal and bend the car into the corner, just to give yourself a little more road - enough extra road to finish the braking. If you find that you've finished braking before the throttle application point in these corners, then you didn't brake late enough. (BTW, if the car won't turn in when you release a little brake pressure, then you probably need to reduce the front brake bias; likewise, if the car swaps ends when you turn in, add some front brake bias).

m17rkj · 20-04-2007, 19:12

Good stuff that. my ibeefa responds well to trail braking, a little extra nudge on the steering as you turn in can get the rear a bit skippy, good fun!

GTA_vRS · 10-07-2007, 17:33

I trailbrake (or sometimes just use a lift to help tuck the nose in) habitually on road and track. I find the weight balance of the car front to rear, affected by brakes and throttle, is more important to steering well than what you do with the steering wheel. On track, the benefits of trail braking are huge, unless you drive a really pointy car.

If you don't trailbrake, particularly on track, you can reach what I'd call a false limit where you understeer on corner entry, convinced you've reached the limit of the car, when in fact it's a technique problem.

I'm always very wary of journalists saying such and such a car understeers or oversteers, these are things the driver does to the car, not the other way around!

Tom_vRS · 10-07-2007, 19:15

I have done this to great effect when pushing on really hard, and have done for a good year or so now. Its pretty easy to get right, and allows you to carry more speed into the corner, with less tyre squeal to boot!

storm monkey · 10-07-2007, 19:16

I presume this forms part of the basis of left foot braking in rallying, as you "shift" the weight of the car from front to rear, and vice versa.

Phil

smstext · 10-07-2007, 20:39

does it say anything about it being for a rear wheel drive?

faboka vrs · 11-07-2007, 08:56

Looks familar.

I always braked like this when briskly driving ever since I past my test.

devonutopia · 11-07-2007, 13:25

Well, to put the other side, I was told I should not be braking to put weight on to the front wheels during the corner, as this is what unweights the back end and causes oversteer / skidding (essentially pushing all weight onto one front tyre) - I guess this is the case with full braking in the bend, but I was told to scrub speed off before the bend, and be just on the gas a bit through the corner. Also, I was told not to take the racing line but to position myself on the left (for a right hander) and by the centre line (for a left hander) to increase vision for myself and oncoming cars.

KenONeill · 11-07-2007, 13:26

Works beautifully with Skodas, cos you get the weight transfer done before turning.

faboka vrs · 11-07-2007, 13:35

Quote:

Originally Posted by devonutopia

Well, to put the other side, I was told I should not be braking to put weight on to the front wheels during the corner, as this is what unweights the back end and causes oversteer / skidding (essentially pushing all weight onto one front tyre) - I guess this is the case with full braking in the bend, but I was told to scrub speed off before the bend, and be just on the gas a bit through the corner. Also, I was told not to take the racing line but to position myself on the left (for a right hander) and by the centre line (for a left hander) to increase vision for myself and oncoming cars.

You got told the roadcraft way. Roadcraft isnt the fastest way but the safest way.

ScoobyChris · 11-07-2007, 13:41

I agree with your approach, Jase and trail braking is not really a technique I've found a need for in road driving, although if you're comfortable LFB, it can be used to good effect in an auto where you can trail brake and feed power to keep the car perfectly balanced.

Should be applicable to all drives of car though as it's just a technique to shift weight over the front wheels, much like applying power is a way of shifting weight over the rear wheels.

Chris

fab16v · 01-08-2007, 19:49

I've been trail-braking while pushing on or on track days for quite a while now. Was a technique I picked up back in my karting days and it's just stuck with the car too. Have always prefered driving with a light tail end when pushing on or racing. Is easier to carry on driving fast with a bit of oversteer than understeer. One of the people I've seen racing recently who uses it to good effect is Lewis Hamilton, especially at Monaco. Reminds me of my style when karting.

smstext · 01-08-2007, 23:08

he is an ex karter too.

andypandypoos · 02-08-2007, 10:59

aren't they (almost) all ex-karters?

ScoobyChris · 02-08-2007, 11:09

I'm pretty sure most of them start in karts before moving through the bigger and badder cars up to F1.... I was under the impression that Lewis was one of the few drivers who didn't use trail braking to unsettle the car and braked before the corner to drive round it on the throttle to maintain grip and minimise steering input....

Chris

20-04-2007, 09:34	#1
ScoobyChris Briskodian Join Date: Mar 2003 Location: Andover Posts: 18,198 Members Car: Fiat Panda Thanks: 15 Thanked 337 Times in 290 Posts	Trail Braking What is trail braking? In essence, it means continuing to brake after having turned in for a corner. The further you progress into the corner, the more you turn the steering wheel and the more pressure you release from the brake pedal. Typically, the procedure goes like this: -You are hurtling in a straight line toward a corner; -You apply the brakes - fully - while still traveling in a straight line; -At some point, you release a little pressure from the brakes and start to turn in; -As you bend into the corner and approach the throttle application point, you progressively release the rest of the pressure from the brake. What's the point of it? Trail braking helps you rotate the car into a corner by controlling the transfer of weight onto the front tyres, giving them more stick, and thus compensating for any understeering tendency the car would otherwise have. The alternative is: do all of your braking in a straight line, then release the brakes entirely, then turn in. The trouble with this technique is that when you release the brakes, weight - and therefore stick - will be removed from the front tires, just when you need them to be loaded enough to turn the car into the corner. So - unless the car is set up to be driven like this - it will understeer away from the corner. This is typical behavior for 'street' (aka massively understeering) cars that have been adapted for racing. On the other hand, a 'proper' race car will probably oversteer if you don't trail brake. If you turn into a corner with your feet off both brake and throttle, the front tires will have all their traction budget available for turning while the back wheels will be doing some (engine) braking. Net result: oversteer. Application of the brakes settles down the oversteer by substituting a proportionately balanced loss of steering traction (because the brakes are biased towards the front). In fact, you use the brake pressure to control the rate at which the car rotates into the corner. How much trail braking you do at a particular corner - i.e. what percentage of the corner is taken under braking - depends on the angle of the corner. For a 60° corner, you'd typically only trail for a few percent of the corner, for a 90° corner, you'd typically trail brake for maybe 25% of the corner, and for a bigger corner, you could do it for up to 50% of the corner. You are aiming to trail off the brakes until they are released completely at or before the throttle application point (which typically occurs somewhere before the geometric apex). Another way of looking at trail braking is: what you're doing is braking so late for a corner, that you're never going to make it if you carry on in a straight line. In order just to stay on the track, you have to release a little of the pressure on the brake pedal and bend the car into the corner, just to give yourself a little more road - enough extra road to finish the braking. If you find that you've finished braking before the throttle application point in these corners, then you didn't brake late enough. (BTW, if the car won't turn in when you release a little brake pressure, then you probably need to reduce the front brake bias; likewise, if the car swaps ends when you turn in, add some front brake bias). __________________ Holding up the traffic in a little Italian..........

20-04-2007, 19:12	#2
m17rkj Briskodian Join Date: Dec 2004 Location: Calgary, Alberta, Canada. Posts: 1,164 Members Car: 2005 focus ZTW Thanks: 16 Thanked 14 Times in 14 Posts	Re: Trail Braking Good stuff that. my ibeefa responds well to trail braking, a little extra nudge on the steering as you turn in can get the rear a bit skippy, good fun! __________________ "I don't even know what street Canada is on." Al Capone.

10-07-2007, 17:33	#3
GTA_vRS Briskodian Join Date: Jul 2007 Location: Winchester Posts: 10 Members Car: Alfa 156 GTA SW Thanks: 0 Thanked 0 Times in 0 Posts	Re: Trail Braking I trailbrake (or sometimes just use a lift to help tuck the nose in) habitually on road and track. I find the weight balance of the car front to rear, affected by brakes and throttle, is more important to steering well than what you do with the steering wheel. On track, the benefits of trail braking are huge, unless you drive a really pointy car. If you don't trailbrake, particularly on track, you can reach what I'd call a false limit where you understeer on corner entry, convinced you've reached the limit of the car, when in fact it's a technique problem. I'm always very wary of journalists saying such and such a car understeers or oversteers, these are things the driver does to the car, not the other way around!

10-07-2007, 19:15	#4
Tom_vRS Briskodaholic Join Date: Dec 2004 Location: Fenland, Cambridgeshire Posts: 11,559 Members Car: '97R BMW 328i Saloon Thanks: 679 Thanked 436 Times in 313 Posts	Re: Trail Braking I have done this to great effect when pushing on really hard, and have done for a good year or so now. Its pretty easy to get right, and allows you to carry more speed into the corner, with less tyre squeal to boot! __________________ 97/R BMW 328i in Boston Green.

10-07-2007, 19:16	#5
storm monkey Briskodian Join Date: Nov 2006 Location: North West Cumbria Posts: 311 Members Car: VW Corrado Storm Thanks: 6 Thanked 14 Times in 10 Posts	Re: Trail Braking I presume this forms part of the basis of left foot braking in rallying, as you "shift" the weight of the car from front to rear, and vice versa. Phil __________________ My Car - 2.0 TDI Octavia L&K My Toy - 95 Corrado VR6 STORM SWMBO's - 55 Navara

10-07-2007, 20:39	#6
smstext 2.0 FSI Sport. Join Date: May 2007 Location: oxon Posts: 9,717 Members Car: Octavia Mk2 FSI Sport Thanks: 11 Thanked 307 Times in 274 Posts	Re: Trail Braking does it say anything about it being for a rear wheel drive? __________________ Oxon Meet Feeler 2009 please add your input, click here

11-07-2007, 08:56	#7
faboka vrs Briskodian Join Date: Oct 2003 Location: Merseyside Posts: 6,058 Members Car: 2004 Fabia vRS TDI PD130 Thanks: 14 Thanked 46 Times in 46 Posts	Re: Trail Braking Looks familar. I always braked like this when briskly driving ever since I past my test. __________________ John 2004 Skoda Fabia vRS - Xenons - Heated Seats - Cruise Control - Passenger Airbag Deactivation switch - Side Airbags

11-07-2007, 13:25	#8
devonutopia Mongreller Join Date: Apr 2003 Location: Exeter / Devon Posts: 30,109 Members Car: Skoda Fabia Mongrel Images: 5 Thanks: 75 Thanked 353 Times in 296 Posts	Re: Trail Braking Well, to put the other side, I was told I should not be braking to put weight on to the front wheels during the corner, as this is what unweights the back end and causes oversteer / skidding (essentially pushing all weight onto one front tyre) - I guess this is the case with full braking in the bend, but I was told to scrub speed off before the bend, and be just on the gas a bit through the corner. Also, I was told not to take the racing line but to position myself on the left (for a right hander) and by the centre line (for a left hander) to increase vision for myself and oncoming cars. __________________ Jason - Only a Skoda. Custom Fabia Bonnet Lifter Kits - £45! Click Me. Cheesy bonnet lifter video to "raise me up" http://www.youtube.com/watch?v=hMnGECEi5Oc See the mongrel's 260bhp Dyno Video!

11-07-2007, 13:26	#9
KenONeill Briskodian Join Date: May 2006 Location: Normally in Scotland! Posts: 11,249 Members Car: Octavia TDi110 Thanks: 65 Thanked 562 Times in 550 Posts	Re: Trail Braking Works beautifully with Skodas, cos you get the weight transfer done before turning.

11-07-2007, 13:41	#11
ScoobyChris Briskodian Join Date: Mar 2003 Location: Andover Posts: 18,198 Members Car: Fiat Panda Thanks: 15 Thanked 337 Times in 290 Posts	Re: Trail Braking I agree with your approach, Jase and trail braking is not really a technique I've found a need for in road driving, although if you're comfortable LFB, it can be used to good effect in an auto where you can trail brake and feed power to keep the car perfectly balanced. Should be applicable to all drives of car though as it's just a technique to shift weight over the front wheels, much like applying power is a way of shifting weight over the rear wheels. Chris __________________ Holding up the traffic in a little Italian..........

01-08-2007, 19:49	#12
fab16v Briskodian Join Date: Mar 2003 Location: Somewhere in Herts Posts: 3,105 Members Car: Hyundai Coupe V6 Thanks: 0 Thanked 0 Times in 0 Posts	Re: Trail Braking I've been trail-braking while pushing on or on track days for quite a while now. Was a technique I picked up back in my karting days and it's just stuck with the car too. Have always prefered driving with a light tail end when pushing on or racing. Is easier to carry on driving fast with a bit of oversteer than understeer. One of the people I've seen racing recently who uses it to good effect is Lewis Hamilton, especially at Monaco. Reminds me of my style when karting. __________________ Graeme Ex Skoda owner twice over.

01-08-2007, 23:08	#13
smstext 2.0 FSI Sport. Join Date: May 2007 Location: oxon Posts: 9,717 Members Car: Octavia Mk2 FSI Sport Thanks: 11 Thanked 307 Times in 274 Posts	Re: Trail Braking he is an ex karter too. __________________ Oxon Meet Feeler 2009 please add your input, click here

02-08-2007, 11:09	#15
ScoobyChris Briskodian Join Date: Mar 2003 Location: Andover Posts: 18,198 Members Car: Fiat Panda Thanks: 15 Thanked 337 Times in 290 Posts	Re: Trail Braking I'm pretty sure most of them start in karts before moving through the bigger and badder cars up to F1.... I was under the impression that Lewis was one of the few drivers who didn't use trail braking to unsettle the car and braked before the corner to drive round it on the throttle to maintain grip and minimise steering input.... Chris __________________ Holding up the traffic in a little Italian..........

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