Just finished watching one of the numerous Chris Harris videos about driving technique, in particular the benefits of left foot braking in a front wheel drive car.

This is a subject I rarely see discussed in this forum yet it seems to have some large advantages, especially when the car is equipped with an LSD.

So, how many of you are experienced in left foot braking, and if you are, can you share your observations from performing such in a Honda / Acura?

Video below for reference:

http://youtu.be/4ZN1aP1o_m8

 

I left foot brake in my road car... That's how I built it up to be second nature so when I adopted it in the race car I didn't have "think" about it. I don't left foot brake where downshifting/rev-matching is concerned but on corners where I need to modulate speed, dip the nose or settle car. I've heard about doing it on exit during moments of under-steer to load the diff like he mentions but have not adopted it for myself. I don't get boat loads of power-understeer in the ITA CRX though because of the low power so this would only apply to very tight/slow corners for me.

 

2:57 says it all.

 

Thats some good info there

 

I've tried it before... I think my left foot was too accustomed to track clutches that require a decent amount of force. When I hit the brake it was an immediate if I wasn't strapped in I would have kissed the windshield moment. Every now and then I'll try it easing it carefully, I like to practice many different techniques.

 

Left foot braking is a nice tool to have in the box! I use it all the time in corners that i don't need to downshift going into, as well as to control understeer.

 

This is something I would definitely like to be proficient at but have a while to go before I am there.

 

my nasa instructer was showing me his left foot braking techinque in a ride along and he's been his TT class champ for 4 or 5 years running so I guess it helps. he told me just to practice on the street and to stop using my right foot for braking.

 

i learned on Karts when i was little... it comes natural now. i use it when auto-xing when every milisecond is critical, on roadcourse not so much...

 

after my injury, i have to retrain my left foot

 

What did you do to your foot spence?

 

sprained my left ankle real bad a few month ago. its getting way better but i didn't realize i couldn't lfb until the other day when i tried it in the daily.

 

Ohhh ankle sprains are the worst!
They take forever to heal.

 

I'm on the fence on this. Autocross, Rally, Oval Racing, and maybe things like F1 all can benefit in small ways from left foot braking. Everything else: it's never been proven to have any advantage. 2:57 talks about using the brake for weight transfer, it has nothing to do with which foot you use to accomplish this. The reason people THINK it has an advantage is that most people in places like DTM, WTCC, BTCC, etc. all started in karts where they've grown up thinking left foot-slow, right foot-go.

The thing with FWD cars needing to "load up" the diff means you have a bad diff. Either way is fine, but it's been argued many times if LFB is better for anything, and it's all a comfort thing. I've seen throttle/brake traces on data proving that there is no conceivable difference between the time from brake to gas or visa-versa using one foot or two. In fact, in the 24H cars, we're all advised NOT to LFB because the slight overlap adds tangible wear to the brake system.

 

I have never found this to be beneficial in road racing (at least for me). Weight transfer can be done with throttle modulation. Some people say it helps to shave time off by eliminating the "foot dance" between gas and brake pedals, but then again I never found this to be true for me.

 

Yeah, this is what I'm talking about, there is little or no time in that dance. It can also be done VERY fast with one foot. I have data showing that the computer cannot even see the difference, and often times picks up an overlap with LFB, usually wearing the brakes.

 

So these drivers are wrong?

I think you guys mis understood the intention of the video, which is how to come out of the corner with a greater speed, i.e. with the diff etc. The weight transfer was for the more 'thrill' aspect of getting the FWD car sideways.

As far as saying a bad diff, did you not listen to the video? It seems like you like to argue with everyone on here because you drive for a team etc.

 

My background is gravel rallying, and I have to say that in that area if you can't left foot brake then you will be off the pace. On a loose surface, left foot braking allows the driver to improve turn in, as well as trim the balance of the car mid-corner. This is especially important for rallying as you can't remember or get to practice every corner, so if a corner tigthens a little on you then you can squeeze a little more brake and get it to turn in more. Staying on the throttle also helps to keep the nose of the car tucked in and pulling through the corner.

The transition between throttle and braking is usually smoother with left foot braking once the driver develops the feel in their left foot. This all helps to get the car settled. Mind you, all of this can be quite hard to do if you don't have a dog box or sequential gearbox if you have to go down a gear mid-corner and your left foot is on the brake. Our rally car has a sequential, so the clutch is pretty much only used off the start line then my driver brakes exclusively with his left foot

 

How does one heel-toe with left foot braking? -as in blipping the throttle to match revs?

And on hard braking turns like Turn 11 at Infineon or the Keyhole at Mid-O.. If you left foot brake, how do you downshift when using the clutch? Using the left foot to use the brake and load the front end I understand...but not sure how it's done while heel toeing.

 

Interesting. Wouldn't shifting weight to an already heavy front FWD car increase understeer?

 

I don't care about the video, the OP showed curiosity about left foot braking. Weight transfer is not for thrill, though it can lead to it, and I think the driver in that video was avoiding the question since he mentioned nothing about why his LEFT foot was doing braking, and he went straight for the general topic of trailing brake on entry, using oversteer to prove the concept. Even later the passenger kept hanging on the LFB concept and I still don't see how it could do anything with which foot he used to add forward weight and get the car sideways.

Drivers that left foot brake are not wrong at all. They've gotten used to something and stuck with it, nothing wrong there. There's no proof one way or another (except in the ends of the sport I've mentioned). I'm playing devil's advocate here and arguing that both ways are fine. I think for a production car that requires a clutch to downshift, LFB has no merit. I know nothing about the driver in the video, but I have a feeling he is used to something with a sequential gearbox and was left foot braking out of habit. In both production cars with H-pattern boxes and GT cars and prototypes with sequential boxes, I right foot brake since I am comfortable with it. My codriver at Stevenson, a guy that is extremely talented, left foot brakes the GT car and right foot brakes the GS car. No preference, he just grew up in karts and Formula cars, so he is comfortable driving on the hairy edge with his left foot on the stop pedal.

If you want answers from people that don't do this for a living, and by description, offer unprofessional opinions while their money isn't on the line, I'll step back. I comment on things I know in an as-honest way as I can. Please don't degrade my comments because I am "on a team". I have nothing against people stating their opinions, and have even less against people proving or disproving theories with fact, regardless of occupation. I've had to learn a lot about this sport and its associated techniques and have found out a thing or two about how people use their feet in road course racing production cars. I spoken with people about this very topic from many facets of the sport, from karters to former F1 drivers. They all have their opinions on it but all end the sentence with something in regards to personal preference. Nobody has ever been able to prove to me that this technique shaves tangible time off a lap except when on a very slick surface (and often with an AWD/RWD car) or on an oval.

My comment on the differential: If you need the brake to lock up the diff, you have a bad diff. It needs more lockup on acceleration, clearly. I have never heard of people performing, or performed this technique myself in a FWD car. I can see how it would work, but again, feel that's an engineer's end of the car, and don't subscribe to braking while trying to accelerate as quickly as possible. I've never seen brake lights come on on a FWD car LEAVING a corner. I just don't believe it. I could be wrong, honestly, but I'm just basing my opinion on my observations.

 

Dyed-in-the-wool LFB'r here...

For autocross in a FWD vehicle I find it to be a key to extracting every bit of time out of a course. The ability to quickly and deftly move weight around, as well as alter speed efficiently beats RFB every time. Too much time delay to move your right foot back and forth, plus you get more fore/aft weight transfer coming all the way off the gas before braking (and vice versa).. It's especially important in the dynamic situation of making minor speed adjustments since no run is ever perfect. Can you be fast without it? Sure. Could you be faster if you were good at it? Probably, IMO.

On a track, it's simply one tool in the toolbox. Way less important, IMO. Done exclusively (like I do), it gets in the way of other things, so now you have to have equally deft touch in both feet. That's like being ambidexterous. Few people can do that. That why you see so many polarized opinions on the topic for track use.

I learned it many years ago driving an automatic grocery getter on the street. Now I can't not do it.

 

I LFB all the time. Mainly since I rally so it's hard wired into my brain now. LFB is a weight transfer technique but it's about changing the load on the car's tires.

But when he's talking about the diffirential loading in the video (I haven't watched this video fully but there is another video of Chris Harris in a Focus RS doing the same thing) you're using the brakes to keep one tire from spinning and it's in reference to a helical/torsen diff. Bascially using it as a poor man's traction control system.

What you need to do is rest your heel on the floor and rotate off your heel. I am pretty much 100% sure you're keeping your foot off the floor which will put it into a "clutch" mode.

It does matter when using LFB over right foot braking (RFB). Yes, when you hit the brakes you are doing weight transfer. But the difference between LFB and RFB in a FWD car... you are using the power of the engine to overpower the front tires braking force.

So think of it this way... ignoring the dynamic factors but just using for reference that using a specific force, say 80% brake pressure gave you 100% static fricting of your braking grip on the front and rear tires. Now doing 81% put you over that 100% grip which would induce kenetic friction thus making the tires slide. Now, imagine you're using LFB technique, so you are countering the front tires braking force with engine power. Now your front tires are back under the 100% grip threshold but your rear tires are sliding and allowing the rear end to rotate.

Umm... I don't during rally. I pretty much clutchless downshift with throttle blips to rev match and drop the gear in. I get some grinds here and there, but that's a wear and tear item I accept. Kind of the reason why I want to switch over to a dog-box so I can do it all the time.

I'd have to dig up some of my Tarmac Rally videos to see how I was braking, but I was using LFB just as much as when I do gravel rally events. Most of the time on track I'm using LFB to settle the car and control it mid corner. I should do a foot cam of me driving my rally car on the track some day.

 

Professional opinions are great. Keep them up! I have tried left foot braking on track, but with a clutch in a FWD car, I have never been able to get faster lap times using LFB. Perhaps lack of talent or the will to commit enough time to learn it. I also tried it in other cars, RWD and AWD, but I always think I am burning up the brakes doing it. It sometimes makes me think I am faster and smoother in transitions in the corners, but data logger says lap times don't get better. I LFB regularly driving automatics on the street, so it is not like I am not used to it.

 

I don't know, man. It sounds like now you're using it to overcome too much front brake bias or other handling issues. There are ways around this which don't involve you fighting horsepower with brake pads. In Rally and Autocross, for different reasons, I can see LFB being beneficial. In Autocross I can see it helping for the same reason as F1-- if the podium is being decided with thousandths of a second, then yes, the 30 times per run you transition from brakes to gas and back again might matter. In rally, where you're knocking the weight forward and back 1000+ times per stage I could also see it helping as moving one foot back and forth would be exhausting. On a road course I feel it will likely always be personal preference-- unless of course you're driving the rare FWD Chevy Stock Car with 66% front bias and a spool differential.

You know what my "poor man's traction control" is? Not flooring the gas pedal. Why do I need to brake? If it's worth the metal it's forged from, your differential is probably already pretty locked up if you're getting wheelspin off the corners, therefore, you're not going to add lock to it by increasing its load, at least not enough to do any benefit. You're much better lifting off the gas pedal, getting your tires working in your favor, learning why it lost traction in the first place, and change your driving for the next time you see the corner. If it's just an inside tire lighting up, its a bad differential, you OBVIOUSLY need more lockup on acceleration. If you're stuck driving a car with an open diff or an LSD that is too open, I still would probably tough it out with driving under the limit of the weakest drive wheel than try to fight it with the brake. Keep in mind, you're slowing all four tires with the brake, not just the one lighting up. Again, I've never seen brake lights coming on when someone exits a corner-- that would be weird, right?

I might have the wrong idea on that, but I really don't subscribe to fixing anything once I've gone to power with the stop pedal. I don't want to argue against the UK's best FWD experts, but I think if you asked them they would probably say it has more to do with preference than anything. They've probably lost more than once to someone without karting background that was working two pedals with one foot. They probably couldn't tell the difference while behind them.