Left Foot Braking
Discussion
:driving: Left foot braking: now thats what I call an advanced driving topic! It's something I first came across at Uni Motor Club in the early 70s, watching Castrol films of Timo Makinen rallying Minis. The theory (and practice if you're a Finnish rally driver) is that you can kill the understeer in a front drive car by braking with the left foot whilst keeping the power on with the right. Power keeps the front wheels turning while the back wheels can be made, ultimately, to lock up. An expert like Timo virtually dances on the pedals, adjusting grip and power at either end of the car to match the traction to the road surface and cornering line. Oh, and if it's a factory car, you just change gear without the clutch and let someone else buy a new transmission. Of course, I then tried it out in my own Mini and discovered that, a) it takes a lot of practice to develop a sensitive left foot, and b) you need to be really trying some for it to have any effect on dry tarmac.
As a road driving technique, left foot braking seemes pretty much like an irrelevance but then, about 10 years ago, I did a one day course with Pentti Airikkala, RAC Rally winner in 1989. http://www.leftfootbraking.com/
Pentti's approach is that LFB is just as relevant for road driving as it is for the track. For example, if you cover the brake with your left foot in a potentially tricky situation, such as a junction with a car that might pull out in front of you, or thick spray and heavy traffic on the M25, you can react to emergencies much more quickly than if you have to move your right foot across from the accelerator. And for fast road driving, LFB ensures better turn in and the ability to finely adjust you line through a corner.
Nowadays, I do consciously brake with my left foot from time to time to stay in practice and I can think of one occasion, at least, where theory became practice. I came around a blind corner to find a car coming towards me on my side of the road, overtaking a policeman on a bicycle! My emergency stop was instant and the fact that the engine then stalled (no spare foot for the clutch) quite irrelevant. And of course, while my own cars are manuals, if ever I drive an auto, it's one foot for each pedal.
It needs practice away from other traffic, but I reckon that left braking is a useful skill for road driving.
As a road driving technique, left foot braking seemes pretty much like an irrelevance but then, about 10 years ago, I did a one day course with Pentti Airikkala, RAC Rally winner in 1989. http://www.leftfootbraking.com/
Pentti's approach is that LFB is just as relevant for road driving as it is for the track. For example, if you cover the brake with your left foot in a potentially tricky situation, such as a junction with a car that might pull out in front of you, or thick spray and heavy traffic on the M25, you can react to emergencies much more quickly than if you have to move your right foot across from the accelerator. And for fast road driving, LFB ensures better turn in and the ability to finely adjust you line through a corner.
Nowadays, I do consciously brake with my left foot from time to time to stay in practice and I can think of one occasion, at least, where theory became practice. I came around a blind corner to find a car coming towards me on my side of the road, overtaking a policeman on a bicycle! My emergency stop was instant and the fact that the engine then stalled (no spare foot for the clutch) quite irrelevant. And of course, while my own cars are manuals, if ever I drive an auto, it's one foot for each pedal.
It needs practice away from other traffic, but I reckon that left braking is a useful skill for road driving.
7db said:
Most useful for lighting up the brake lights whilst pulling away from the tailgater.
Yup. That's what I use it for. In general driving I don't LFB - I don't really have the sensitivity with the left foot I should have for that.
But its every so handy for confusing SkoolRunMum behind in her 4x4. Its very amusing watching them drop back as the lights go on - whilst I'm accelerating away...
GreenV8S said:
There seems to be a trend these days for 'throttle by wire' systems to kill the engine power as soon as you touch the brakes.
I will never buy a manual car that does that. If its part of some wonderful computerised flappy paddle rev matching system then I might, I suppose...
Can be useful to shift the weight forward in a front wheel drive car.
If you experiment with it in corners you will find that keeping the car at full throttle AND left foot braking will, once out of the corner have an instant supply of power as the engine it still trying to acclerate and will be closer to the powerband than a car rising up from idle....
I rarely do it now but it is fun to feel the difference.
WARNING! If you try this for the first time you will more than likely press the brake pedal hard and then even harder imagining it is the clutch and expecting the opposite to happen than actually is! Proceed with caution
If you experiment with it in corners you will find that keeping the car at full throttle AND left foot braking will, once out of the corner have an instant supply of power as the engine it still trying to acclerate and will be closer to the powerband than a car rising up from idle....
I rarely do it now but it is fun to feel the difference.
WARNING! If you try this for the first time you will more than likely press the brake pedal hard and then even harder imagining it is the clutch and expecting the opposite to happen than actually is! Proceed with caution
When I had an Alfa 145 it was useful for taking wet roundabouts at speed. Also when I had a R5 GT Turbo it was great for keeping the Turbo on the boil but in reality it has no place on the road and certinaly not for emergency situation.
Any gain made by reaction time will be far out-weighed by the amount the car will travel forwards due to the engine pushing against the brakes as you can't use the clutch. If you think you need an extra 0.1 seconds reaction time to brake then your not planning ahead well enough.
Any gain made by reaction time will be far out-weighed by the amount the car will travel forwards due to the engine pushing against the brakes as you can't use the clutch. If you think you need an extra 0.1 seconds reaction time to brake then your not planning ahead well enough.
If you don't have ABS then the extra engine inertia may be an advantage, it is much easier to lock the wheels if you are out of gear. Hence you would normally brake to a standstill in gear with the clutch up, only declutching at the last moment if you knew you had got everything under control and going to stop in time.
Like WoodyTVR said, I use LFB to keep the turbo from stalling through corners. Gives you instant power as soon as you can see the corner exit and avoids you sitting there in "lag land" waiting for everything to happen again. Makes for much smoother progress. In a 4WD it also helps to shift drive to the rear wheels, killing understeer.
However, I disagree that the engine will be pushing against the brakes in an emergency stop. By simply taking your foot completely off the throttle, you'll have the added advantage of engine braking, particularly useful in a 4WD car.
A few years back I was watching the Audis in the BTCC at Oulton Park. I asked Tiff Needell, who was stood next to me, whether the 4WD helped them on the brakes, and he said yes definitely. I'd have thought that if you were able to reach the limit of the tyres' grip with the brakes alone, engine braking wouldn't add anything to the ability to slow down, but apparently it does...
However, I disagree that the engine will be pushing against the brakes in an emergency stop. By simply taking your foot completely off the throttle, you'll have the added advantage of engine braking, particularly useful in a 4WD car.
A few years back I was watching the Audis in the BTCC at Oulton Park. I asked Tiff Needell, who was stood next to me, whether the 4WD helped them on the brakes, and he said yes definitely. I'd have thought that if you were able to reach the limit of the tyres' grip with the brakes alone, engine braking wouldn't add anything to the ability to slow down, but apparently it does...
woodytvr said:
When I had an Alfa 145 it was useful for taking wet roundabouts at speed. Also when I had a R5 GT Turbo it was great for keeping the Turbo on the boil but in reality it has no place on the road and certinaly not for emergency situation.
Any gain made by reaction time will be far out-weighed by the amount the car will travel forwards due to the engine pushing against the brakes as you can't use the clutch. If you think you need an extra 0.1 seconds reaction time to brake then your not planning ahead well enough.
Keeping the turbo on the boil was another advantage quoted by Pentti on the course, e.g. when anticipating an overtaking opportunity requiring instant maximum torque. However, I reckon turbo installations have improved (the course cars were a 4wd Sierra Cosworth and a Fiesta Turbo, both amusingly fitted with dual controls that included two steering wheels per car!) to the point where this is unnecessary, at least provided you're in the right gear. I never bother in my Impreza. Also, I was never keen on flashing brake lights to those following, whilst at the same time signalling right and pulling out to overtake!
On the subject of emergency braking, it takes most people a good deal longer than 0.1 of a second to physically lift a foot of one pedal, move it across to another, and then to press down. The difference in total stopping time can be genuinely significant and provided you lift off the throttle with your right foot, there is no issue of fighting against the engine power.
gdaybruce said:
On the subject of emergency braking, it takes most people a good deal longer than 0.1 of a second to physically lift a foot of one pedal, move it across to another, and then to press down. The difference in total stopping time can be genuinely significant and provided you lift off the throttle with your right foot, there is no issue of fighting against the engine power.
Obviously I was exagerating the point but if your lack of observation and forward planning requires you to LFB in an emergency then good luck to you, you'll need it.
I also think that LFBing my 330D Touring to a stand still would take a significant longer distance to stop than braking in the normal manner, even in an emergency.
>> Edited by woodytvr on Friday 30th September 15:34
My 2p.
The only place I consider that left foot braking has in normal road driving is in low speed manoeuvring an automatic, especially in a confined space and even more so with a cold engine.
I understand Don's technique re LFB plus accelerating to confuse following traffic. Fair enough but it needs great delicacy with left foot.(Remembers an old road rally trick of having a brake light kill switch. Stops a following competitor driving on your lights and thus being able to spot bends and junctions better. Mind you they do sometimes go off into the boondocks as a result..... ooops sorrreeeeee!)
As others have mentioned LFB has no other place on road driving imho and if your driving is such that LFB helps during cornering then I would argue that you are too near the limit for public roads and in event of a coming together a prosecution charge would follow in my book.
Furthermore the way most cars are set up almost all the braking effort is on the front, hence you have to give the brakes some serious work to have much effect with the rears.
Competition vehicles the balance set up is completely different AND adjustable. So applying track and stage techniques on public highway is not that relevant.
The only place I consider that left foot braking has in normal road driving is in low speed manoeuvring an automatic, especially in a confined space and even more so with a cold engine.
I understand Don's technique re LFB plus accelerating to confuse following traffic. Fair enough but it needs great delicacy with left foot.(Remembers an old road rally trick of having a brake light kill switch.
Stops a following competitor driving on your lights and thus being able to spot bends and junctions better. Mind you they do sometimes go off into the boondocks as a result..... ooops sorrreeeeee!) As others have mentioned LFB has no other place on road driving imho and if your driving is such that LFB helps during cornering then I would argue that you are too near the limit for public roads and in event of a coming together a prosecution charge would follow in my book.
Furthermore the way most cars are set up almost all the braking effort is on the front, hence you have to give the brakes some serious work to have much effect with the rears.
Competition vehicles the balance set up is completely different AND adjustable. So applying track and stage techniques on public highway is not that relevant.
I don't think there's any place really for left foot braking on the public roads. Despite what anyone might think, I reckon if what you're doing involves the public highway, you're not really going quickly, and certainly not quick enough that left foot braking would make any difference whatsoever.
I think you're much more likely to end up in the crap than out of it, with left footing.
I think you're much more likely to end up in the crap than out of it, with left footing.
This year I have started left foot braking on track, and it is of benefit in some corners. However, I've yet to beat my fastest times...
The other situation on track that it is useful for is where only a very quick dab of the brake is needed before a quick corner. I've been using it this year at the first bends at Silverstone (Copse) and Snetterton (Riches). I just need a quick dab of the brake, and I find that it is better to do this with the left foot as it saves a bit of time.
The other situation on track that it is useful for is where only a very quick dab of the brake is needed before a quick corner. I've been using it this year at the first bends at Silverstone (Copse) and Snetterton (Riches). I just need a quick dab of the brake, and I find that it is better to do this with the left foot as it saves a bit of time.
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