Left foot braking

[ph123]

IMHO it has very limited circuit use indeed, very dependant upon racecar. As suggested above, it’s a rally driving technique which I think over-complicates anything you’re trying to achieve on a circuit.
And the best use of the left foot after using the clutch pedal is as a bracing member for your body, to take away any temptation to put weight through your arms and effect that may have on steering inputs. As important as I see this on road car driving, it’s even more important for circuit racers where on-the-limit car control is a critical (although secure location through proper competition seating and belts help no end.)

[maddog993]

R_U_LOCAL said:

Is it a good technique for the road though? No, I don't think so, and here's why...

Firstly, in competitive driving, shortening lap times / stage times is an absolute priority. Shaving a few hundredths off a lap time by reducing the time between accelerating and braking through LFB is therefore very useful.

On the road, timings are completely irrelevant. There are thousands of more important considerations for a good road driver to deal with before they get anywhere near "how long Will the journey take?"


Those of you who say that you drive automatics and you find it useful to "hover" over the brake pedal, think about this. If you're genuinely not placing any pressure on the pedal whilst "hovering", then all well and good, but I know from years of teaching that people who hover over the clutch pedal usually just rest their foot on the pedal just slightly, rather than hovering over it. I teach students to take their foot right off the pedal to reduce wear on the release bearing.

If you do the same thing with your left foot in an automatic - just rest your foot on the brake pedal slightly - then you'll just apply the brakes slightly when you do. Not enough to notice, not enough to slow the car down at all, but just enough to press the pads against the discs slightly. Over time, this generates heat in the pads, discs and fluid, and as we well know, heat is the main thing which will cause your brakes to fade or even fail. If you think that by hovering over the brake pedal, you're reducing the time it takes you to press the pedal, then I'm afraid you're making a false economy. Any tiny gains you make in brake application time will be more than lost if you've inadvertently heated your brakes to excess.

Another good reason not to LFB on the road has already been identified in this thread. Your left foot has become accustomed to pressing the clutch in a very binary fashion. Re-teaching your left foot to have the sensitivity of your right is difficult and time consuming, and not something I recommend on the road.

So, in summary, it's a useful and effective competition driving technique, but totally unnecessary on the road.

With the greatest respect (and with humble deference to your class 1 instructor status to my inferior class 2 ), with regard to the potential relevance of left foot road braking I disagree;

On the basis that braking distance is factored to 4 components - Human Perception time, human reaction time, vehicle reaction time and vehicle braking capability and also on the premise that in this particular case we are referring to braking in-extremis/ emergency braking;
With perception time taken for a driver to see a hazard, the brain to recognize the hazard and respond accordingly it is generally regarded as being around 1/4 to 1/2 second. once this process is completed it becomes a matter of how long it takes- (in conventional right foot braking)- for the foot to move from the accelerator pedal to the brake pedal - this is shown to take anything from 1/4 to 3/4 of a second. At 60mph within the 1/4 second taken to move the right foot to the brake pedal a vehicle will have travelled around 7metres or within 3/4 second it will have travelled 21 metres. With the left foot over the brake pedal (and whilst I appreciate your point regarding inadvertantly resting ones foot on the pedal- which will potentially affect the vehicle reaction time and vehicle braking capability- it is honestly not something I do) this creates a potentially 7 -21m shorter stopping distance which is potentially very significant.

I agree it is not for everyone and to practice it it is important that the act of left foot braking becomes utterly instinctive and 'natural' - it does indeed take time for the left foot to become accustomed to the feel and progression of braking as opposed to the clutch pedal but it is a far from insurmountable obstacle and I believe that, should a driver choose to do so- particularly in a two pedal vehicle (of ever increasing significance with the increasing popularity of semi-auto gearboxes)- left-foot braking has potental relevance to road driving.

Edited by maddog993 on Tuesday 14th August 13:30

[hardboiledPhil]

maddog993 said:

I agree it is not for everyone and to practice it it is important that the act of left foot braking becomes utterly instinctive and 'natural' - it does indeed take time for the left foot to become accustomed to the feel and progression of braking as opposed to the clutch pedal but it is a far from insurmountable obstacle and I believe that, should a driver choose to do so- particularly in a two pedal vehicle (of ever increasing significance with the increasing popularity of semi-auto gearboxes)- left-foot braking has potental relevance to road driving.

Funny how it takes ages to get used to it in a car but step into a kart and you'll be braking at the limit after a couple of laps.

[time2react]

When all is said and done, as long as you stop when you really have to, one is as good as the other.
I think drivers need to spend more time working on their hazard perception than on their tap dancing.

[R_U_LOCAL]

maddog993 said:

With the greatest respect (and with humble deference to your class 1 instructor status to my inferior class 2 ), with regard to the potential relevance of left foot road braking I disagree;

On the basis that braking distance is factored to 4 components - Human Perception time, human reaction time, vehicle reaction time and vehicle braking capability and also on the premise that in this particular case we are referring to braking in-extremis/ emergency braking;
With perception time taken for a driver to see a hazard, the brain to recognize the hazard and respond accordingly it is generally regarded as being around 1/4 to 1/2 second. once this process is completed it becomes a matter of how long it takes- (in conventional right foot braking)- for the foot to move from the accelerator pedal to the brake pedal - this is shown to take anything from 1/4 to 3/4 of a second. At 60mph within the 1/4 second taken to move the right foot to the brake pedal a vehicle will have travelled around 7metres or within 3/4 second it will have travelled 21 metres. With the left foot over the brake pedal (and whilst I appreciate your point regarding inadvertantly resting ones foot on the pedal- which will potentially affect the vehicle reaction time and vehicle braking capability- it is honestly not something I do) this creates a potentially 7 -21m shorter stopping distance which is potentially very significant.

I wasn't aware that we were talking solely about emergency braking. The context of my reply was on the understanding that this discussion was about left foot braking as a general high performance driving technique.

However, how many times have you used emergency braking in the last 12 months? Twice? Once? I haven't used emergency braking at all in the last 12 months, so the percentage of situations where your method would (theoretically) be an advantage is tiny. Most brake applications are made in plenty of time as part of a planned approach to hazards which are potential, developing or actual. In everyday driving, therefore, you can discount the time it takes your foot to move from gas pedal to brake pedal, as this is taken into account as part of the planned approach.

Let's, however, look at your point about emergency braking. The danger in these situations if you're left foot braking, is that you'll inadvertently keep the gas pedal pressed whilst you apply the brakes. Now, you might only leave it pressed for a short time whilst you're braking, but that application of power, no matter how short, will always lengthen the braking distance. I'd suggest that it would lengthen it by the same amount that you have suggested is lost in moving your right foot from gas to brake.

Emergency braking with your right foot takes away any possibility that you will still have power applied during the braking.

Another consideration in emergency braking is that, from very early on in our driving experience, we're taught to accompany emergency braking with dipping the clutch. In emergency situations, it is well documented that people revert to basic responses, and one of the most basic response for drivers is the emergency stop. Now, can you say with 100% confidence that you wouldn't inadvertently press both pedals in your two-pedal car in a dire emergency?

maddog993 said:

I agree it is not for everyone and to practice it it is important that the act of left foot braking becomes utterly instinctive and 'natural' - it does indeed take time for the left foot to become accustomed to the feel and progression of braking as opposed to the clutch pedal but it is a far from insurmountable obstacle and I believe that, should a driver choose to do so- particularly in a two pedal vehicle (of ever increasing significance with the increasing popularity of semi-auto gearboxes)- left-foot braking has potental relevance to road driving.

I disagree for the reasons I've already outlined. Another poster has also pointed out another downside to the technique which I hadn't considered, but which, having given it some thought, is entirely correct.

I drive a two-pedal semi-auto car, and there is a nice sized footrest to the left of the footwell. Most high-performance cars have a similar footrest, and when pressing on, an ideal way to brace yourself in your seat during cornering or heavy braking is to press against the footrest. If you drive everywhere with your foot "hovering" over the brake pedal, you're far more susceptible to the forces of gravity moving you around in your seat.

[m3psm]

Although I do use lfb on the road in my auto, I agree that it's not generally appropriate (definately not for a novice) and isn't of any great great benefit, even in an emergency.

On track I personally find it useful to help reduce understeer on certain corners by keeping some bit on the brakes during turn in whilst feathering the throttle, but that's just me.

The reason I do it on the road is practice my left foot modulation of the pedal as I get much more road time than track time, so I look at it as a bit of practice that costs nowt.

Whilst happilly hovering over the brake pedal with my left foot, when I have recently had to do an emergency, I stangely still chose to brake with my right foot with no problem. I suppose it's instict. Also when racing I generally use my right foot to brake and only use lfb on certain problem corners, but seem to deal with the interface between the two with no problems.

[maddog993]

R_U_LOCAL said:

maddog993 said:

With the greatest respect (and with humble deference to your class 1 instructor status to my inferior class 2 ), with regard to the potential relevance of left foot road braking I disagree;

On the basis that braking distance is factored to 4 components - Human Perception time, human reaction time, vehicle reaction time and vehicle braking capability and also on the premise that in this particular case we are referring to braking in-extremis/ emergency braking;
With perception time taken for a driver to see a hazard, the brain to recognize the hazard and respond accordingly it is generally regarded as being around 1/4 to 1/2 second. once this process is completed it becomes a matter of how long it takes- (in conventional right foot braking)- for the foot to move from the accelerator pedal to the brake pedal - this is shown to take anything from 1/4 to 3/4 of a second. At 60mph within the 1/4 second taken to move the right foot to the brake pedal a vehicle will have travelled around 7metres or within 3/4 second it will have travelled 21 metres. With the left foot over the brake pedal (and whilst I appreciate your point regarding inadvertantly resting ones foot on the pedal- which will potentially affect the vehicle reaction time and vehicle braking capability- it is honestly not something I do) this creates a potentially 7 -21m shorter stopping distance which is potentially very significant.

I wasn't aware that we were talking solely about emergency braking. The context of my reply was on the understanding that this discussion was about left foot braking as a general high performance driving technique.

However, how many times have you used emergency braking in the last 12 months? Twice? Once? I haven't used emergency braking at all in the last 12 months, so the percentage of situations where your method would (theoretically) be an advantage is tiny. Most brake applications are made in plenty of time as part of a planned approach to hazards which are potential, developing or actual. In everyday driving, therefore, you can discount the time it takes your foot to move from gas pedal to brake pedal, as this is taken into account as part of the planned approach.

Let's, however, look at your point about emergency braking. The danger in these situations if you're left foot braking, is that you'll inadvertently keep the gas pedal pressed whilst you apply the brakes. Now, you might only leave it pressed for a short time whilst you're braking, but that application of power, no matter how short, will always lengthen the braking distance. I'd suggest that it would lengthen it by the same amount that you have suggested is lost in moving your right foot from gas to brake.

Emergency braking with your right foot takes away any possibility that you will still have power applied during the braking.

Another consideration in emergency braking is that, from very early on in our driving experience, we're taught to accompany emergency braking with dipping the clutch. In emergency situations, it is well documented that people revert to basic responses, and one of the most basic response for drivers is the emergency stop. Now, can you say with 100% confidence that you wouldn't inadvertently press both pedals in your two-pedal car in a dire emergency?

maddog993 said:

I agree it is not for everyone and to practice it it is important that the act of left foot braking becomes utterly instinctive and 'natural' - it does indeed take time for the left foot to become accustomed to the feel and progression of braking as opposed to the clutch pedal but it is a far from insurmountable obstacle and I believe that, should a driver choose to do so- particularly in a two pedal vehicle (of ever increasing significance with the increasing popularity of semi-auto gearboxes)- left-foot braking has potental relevance to road driving.

I disagree for the reasons I've already outlined. Another poster has also pointed out another downside to the technique which I hadn't considered, but which, having given it some thought, is entirely correct.

I drive a two-pedal semi-auto car, and there is a nice sized footrest to the left of the footwell. Most high-performance cars have a similar footrest, and when pressing on, an ideal way to brace yourself in your seat during cornering or heavy braking is to press against the footrest. If you drive everywhere with your foot "hovering" over the brake pedal, you're far more susceptible to the forces of gravity moving you around in your seat.

Okay all very valid points- firstly to put it in perspective; I drive a manual sports-car, a manual ambulance 'truck' and a manual rapid-response car. The only two-pedal vehicle I currently drive is our SUV which is an auto.
I utilise left-foot braking in all the vehicles (apart from the ambulance truck) in a limited capacity but only exclusively in the auto SUV.

I refer to the use of emergency braking solely on the basis that this demonstrates the most extreme and tangible advantage conferred by left-foot braking in the form of reduced stopping distances. - True, I haven't had to use emergency braking too often and to have had to do so would suggest a lack of roadcraft and failure to read the road correctly. The only relatively recent occasion involved has been a deer running out in front of the vehicle from the woods at the side of the road. The emergency braking involved (in the SUV and with the left-foot!) was spontaneous, natural and involved no mashing of both feet on both pedals. I agree one does not know for sure how one will instinctively react in such a situation until it actually happens but I would reiterate that I have been utilising the technique for over 20 years and have encountered enough situations of one sort or another to feel comfortable that it is an utterly natural part of my personal driving technique and similarly-and importantly- on a subconcious/instinctive level also.
While I defend the technique and the reasoning behind it and use it myself,I would not actively suggest left-foot braking to others and I acknowledge totally that it would be generally frowned upon in the context of emergency driving and the vehicle control 'system'( but then so is heel-and-toeing and I use that also!). However, outside the realm of in-extremis braking the system of balancing the vehicle for cornering is of particular relevance with regard to front-wheel-drive vehicles which usually understeer at the limit as the slip angles are overstepped - the volvo response vehicles we currently use are very prone to understeer and I occasionally use left foot braking to counteract the understeer. In general driving in terms I find the transition from throttle to brake to throttle and the weight- transfer involved may be made smoother and more linear. However, I emphasise that this is all purely personal but equally I can entirely appreciate why the technique be of relevance to others. I really haven't noticed the value of 'bracing' myself round corners using the left foot rest but then surely that would apply to the right foot as well wouldn't it?

[madras]

I thought the primary reason for left foot braking was to reduce understeer with the minimum upset to the car - as used by rally drivers in the 80s. I can see how it could also be used to get the back out but suspect this came after it was first used to reduce understeer. I don't think it has much benefit for improved reaction to braking for the reasons already stated.

[bigburd]

Learn from the man himself Pentti Airikkala

http://www.leftfootbraking.com

[R_U_LOCAL]

Don't get me wrong - I understand the theory behind reducing understeer, but there are other issues to consider in road driving too.

Many modern cars are fitted with electronic stability systems - ESP, ESC, whatever you want to call them. They detect when a car is starting to slide and automatically introduce countermeasures to help bring the car back under control. These systems are developments of traction control systems, but they're capeable of much more than TC. They can cut engine revs and actually apply individual brakes to get the car back on line. However, if you start applying brakes whilst the accelerator is still applied, you'll confuse the system and there is a strong possibility that they won't interject in the correct way.

maddog993 said:

I drive a manual sports-car, a manual ambulance 'truck' and a manual rapid-response car.

If that's the case, then you should seriously reconsider your driving habits whilst on duty. Most emergency vehicles these days are fitted with "black boxes" which record vital information in the event of an accident or incident. They can be interrogated to show what inputs the driver made prior to an accident, what emergency equipment was switched on etc. If things go tits up, then you may have to explain why you were driving in a way that goes against what you were taught, and in a way which may counteract whatever active safety systems are fitted to your car.

How you drive in your own car is, of course, entirely up to you and if LFB works for you, then carry on. As long as you're fully aware of the possible pitfalls.

[R_U_LOCAL]

bigburd said:

Learn from the man himself Pentti Airikkala

http://www.leftfootbraking.com

website said:

The Airikkala Program provides both proven professionals and everyday motorists with a rare opportunity to learn the trade secrets behind successful race & rally driving

As already mentioned, that's a course aimed at improving competitive driving skills, not road skills.

I quite fancy a ride out with Mr Airikkala though. *Prices up course*

Edited by R_U_LOCAL on Tuesday 14th August 19:18

[Robin Hood]

We have numerous geriatrics in this locality who practice left foot braking on a permanent basis, problem is we can never tell when they're planning to stop because the brake lights are constantly on with them resting their foot on the pedal in anticipation of a manoevre in about 3 miles time !

[GreenV8S]

Way back when, left foot braking used to be very popular with rally drivers using a crash box, they would only use the clutch to get off the line and spend the rest of the time using one foot per pedal (clutchless gear changes) one hand steering one hand working the gears. All changed these days with flappy things.

Some time later it become popular to counteract turbo lag and then to bias the handling balance towards oversteer (fwd/4wd) or understeer (rwd).

All pretty irrelevant to road driving though. Do you really think that reducing your reaction time by a tenth of a second is a justification for using a technique like this? Seems to me that the disadvantages dramatically outweigh the benefits.

[maddog993]

R_U_LOCAL said:

Don't get me wrong - I understand the theory behind reducing understeer, but there are other issues to consider in road driving too.

Many modern cars are fitted with electronic stability systems - ESP, ESC, whatever you want to call them. They detect when a car is starting to slide and automatically introduce countermeasures to help bring the car back under control. These systems are developments of traction control systems, but they're capeable of much more than TC. They can cut engine revs and actually apply individual brakes to get the car back on line. However, if you start applying brakes whilst the accelerator is still applied, you'll confuse the system and there is a strong possibility that they won't interject in the correct way.

It would be marvellous if we had some decent vehicles with any of these wonderful devices that would no doubt largely obviate any point in the LFB but unfortunately we currently use ageing 'poverty-spec' V40s that don't have the DSA Traction Control fitted to the T4s (traction is dreadful as is the terminal understeer inherent in such a vehicle-they really are quite nasty). There is a distinct pragmatism in relation to my use/type of use of LFB to the type and nature of vehicle it is performed in (hence, I do not consider it an appropriate technique at all in the Ambulance trucks which do have TC and which also have- by their nature and size- quite volatile/unstable/marked changes in weight transfer and handling )

maddog993 said:

I drive a manual sports-car, a manual ambulance 'truck' and a manual rapid-response car.

R_U_LOCAL said:

If that's the case, then you should seriously reconsider your driving habits whilst on duty. Most emergency vehicles these days are fitted with "black boxes" which record vital information in the event of an accident or incident. They can be interrogated to show what inputs the driver made prior to an accident, what emergency equipment was switched on etc. If things go tits up, then you may have to explain why you were driving in a way that goes against what you were taught, and in a way which may counteract whatever active safety systems are fitted to your car.

I think you're mistakenly accusing us of being a sophisticated service - the only black-boxes in our vehicles are the ones with a bin-bag that we put the rubbish into - perhaps our next generation of fleet vehicles might have them and I do take your point.

GreenV8S said:

All pretty irrelevant to road driving though. Do you really think that reducing your reaction time by a tenth of a second is a justification for using a technique like this? Seems to me that the disadvantages dramatically outweigh the benefits.

I would reiterate that the technique works for me, and as far as I perceive it-irrespective of emergency braking- improves,enhances and complements my ability to make safe, smooth, rapid progress on the road if, and when, I choose to use it. I repeat that I would not actively encourage others to use it but simply that I can envisage and personally relate to how LFB may be potentially usefully deployed in a road context- obviously a controversial view. Equally, I don't 'personally' accept the last point as while there are the benefits described I have not encountered any disadvantages in the manner in which I employ the technique - though I accept others may do so.

Edited by maddog993 on Wednesday 15th August 15:04

[turbomachine]

The first time i tried to left foot brake it was 'intersting' I was driving on a long stretch of clear road doin about 60ish then thought i would try this left foot braking idea. Well i gave my self a fright braked really hard and realised that i needed to change gear cos i braked to about 30 mph , in the confusion of it all i thought my foot was on the clutch and it was still on the brake so i got a second jolt thinking i was depressing the clutch. Finally changed gear and speeded up and thought how stupid that must have just looked, then about 2 seconds later the traffic cops drove past, any earlier and i would have had to come up with a great excuse for them. Needless to say i havn't tried it since

[wong]

I think everyone does an 'emergency brake' the first time they try left foot braking.
It happened the first time I drove an automatic.
To avoid embarrasement , it helps if there are no passengers and other witnesses the first time you try.

[Bagman]

Having practiced Reg's cornering and overtaking advice I'm changing my mind. No need to LFB on the road even if you're half tidy at it. The only time I'd need to get to the brake that quick is in a real emergency situation and in that instance I can either move right foot from the throttle or move left foot from the Jesus pedal.

[K13 WJD]

i use left foot braking to a decent extent when on track, mainly when on dual apex cornerns, to induce a little oversteer on my FWD car.

i'll also use it through some tight sections, where im only looking for a transfer in weight just prior to turn in, but its littery a quick stab with the left foot, just as i turn in. helps reduce initial understeer in my opinion.


also imo LFB has different effects in differnt cars !

[GreenV8S]

K13 WJD said:

i use left foot braking to a decent extent when on track, mainly when on dual apex cornerns, to induce a little oversteer on my FWD car.

That's the main reason I can see for using it - to trim the balance of the car.

[flattotheboards]

iLiekCarz said:

Still makes me laugh when I first tried it:

I was like "ey guys! I've been reading some car mags and they give lots of cool racing tips like LEFT FOOT BRAKING!!"

"Cooooo!!" came the chorus of replies.

"Yeah, watch this lads!" and promptly gave myself a bloody nose from the steering wheel and my buddy promptly strangled himself on the seatbelt.

Of course, being totally amazing (har har!) I had the perfect excuse..

"Hmmm, I think my brakes need warming up first!"