If the braking section is long enough, it is possible to do some really fancy footwork , essentially spending a couple moments with both feet on the brake pedal. This will let you use left-foot braking for a smoother transition from accel>>brake and back from brake>>accel.


Mind you, this is a lot of extra effort, and it's very likely that you'll screw up the amount of braking force needed and negate the extra time you're saving by using the left-foot-braking technique (and smoothly roll on & off the gas & brake simultaneously). I'm not able to pull it off consistently yet, but I'm hoping it will eventually be a useful thing. When I get it right, it's nice to 'pre-load' the throttle to reduce lag and have the power there right when you need it.

-s-

 

*whistles* That's far more complicated than what I was thinking of... I was thinking in terms of having, at points during the operation, left foot doing clutch and brake while right is only doing throttle. Possibly the first time when I'd be glad of having big feet!

Left foot braking itself I think I've got down where I'm gaining a little bit of time by smoothing out the brake/accel transition (non-turbo car) but... man, the extent of dancing on the pedals you described to downshift too is intimidating.

 

It's easier with bare feet or split-sole wrestling shoes. (Wrestling shoes are the poor man's race shoes).

To try and do both the brake and clutch with your left foot sounds pretty impossible. I'm guessing the cluch requires more movement than your foot would be free to do, assuming you could somehow maintain a steady pressure on the brake pedal.

The braking is the important part, there is a ton of time to be gained or lost by braking at the precisely correct moment.

Heel-and-toe rev matching is tough also, the first time you try it. Test it in a straight line, not at full speed when entering a corner. Eventually it becomes less clunky, and after a while it's somewhat comfortable. Eventually you can do it without thinking. Then you'll realize that there are things you haven't yet thought of:

My progression went like this:
1. regular shifting, nothing fancy
2. heel-toe downshift, rev-matching
3. heel-toe double-clutching, rev matching while in neutral (dreaming of dog-box transmissions)

(long time w/o trying anything new)

4. occasional left foot braking mid-corner, for minor understeer correction (Subaru AWD)
5. consistent left-foot braking, 2nd gear only (autocross)
6. more left-foot-braking with transition to standard braking during shifting. As I said before, I'm still not too good at this, but it's fun to try sometimes, mostly as a test of my coordination. I can't do it consistently in a race environment (don't really need to for autocross), but trying new things is a way to keep things interesting without pushing the car past my limits of skill and concentration.



PS Kenku, I noticed your post about Formula SAE cars in a different thread, which school are you with?

-scott-

 

[QUOTE=Kenku]*whistles* That's far more complicated than what I was thinking of... I was thinking in terms of having, at points during the operation, left foot doing clutch and brake while right is only doing throttle. Possibly the first time when I'd be glad of having big feet!

Many years ago I was taught racing techiques by a gentleman by the name of Jackie Cooper. I was teaching the safety course at Limerock and he kind of adopted me as I had a Lotus Europa that I let him run around the track when he wanted to play. He could do things with my car that were unreal and beat my times every time in the same car. (He taught me all I knew, but not all HE knew.) I was racing my RX-3 and my Europa in their respective classes. He taught me a technique called heel and toe shifting that was different than what I've read here. It simply meant that you kept you right heel on the floor and rotated your foot to hit the throttle or brake with your toes. (Allowed a more exact and constant control of brake and throttle as the same angle and foot pressure to the pedals was maintained at all times.) The left foot was used for the clutch only. Most up shifting was done by floating the gears. (Using the engine torque to load and unload the gears so that the shifter moved freely when required, without using the clutch.) Downshifting was not done. The clutch was used when braking for a turn. (Push in the clutch and brake in a straight line, off the brake , turn and coast to apex while selecting the proper gear and engine RPM and accelerate out of the turn.) I later taught the same techniques when I was an instructor at the Federal Law Enforcement Academy and in an exchange program, found that it was also taught at Bob Bondurant's school. The same technique also works with automatic Transmissions, without using the clutch/gear selection. BTW: Left foot braking causes more danger than help. The slightest mistake with the left foot on the brake and the right on the throttle can result in a hasty exit from the roadway. (Usually backwards!!) There is a technique known as "Trail Braking", which uses the emergency brake, that is used by some of the stockers and a few SCCAers that works quite well and is much safer. It allows the rear end to be broken loose for slowing and turning when a turn is too tight for a drift. The secret here is be smooth in everything you do. If anyone would like to try an interesting smoothness test and training technique, tie a shallow rubber or plastic bowl to your passenger seat. (The cheap salad bowls work well. Find one with a base or legs that can be tied down.) Put a tennis ball in the bowl. Now drive around the track without having the ball leave the bowl. It's not as easy as it sounds. Remember that squeeling tires sound impressive, but are a sign of decreased traction. The more traction, the faster the turns.

 

Yeah, I got some fairly nice racing shoes for last christmas. But clutch movement... I think I could maybe manage on the race car, thanks to the puck clutch and the really large amount of travel my gigantic feet are capable of. Maybe not though... enh, I've had strange, impractical ideas before.


I skipped 3 and 4 there, and have been doing the 5th (though in 3rd). Though I might have to teach myself double clutching with the way the synchros are getting in my daily beater... it's slowly becoming a dogbox. I've been teaching myself stuff by incorporating it into how I drive that beater so it's completely natural; I decided at an early track session I needed to learn to heel/toe, so I started doing it on my daily commute, every downshift every time. I noticed the time it was taking me to transition from braking to accelerating and I thought LFB might be useful, so I started doing that too.

... it's helpful that my daily commute involves twisties.

Oh yeah, I'm at Marquette University, in Wisconsin. It's kinda sad that SAE died here... too many engineers of the "I'm here to drink and get a diploma and would be a business major if it would get me more money!" kind. The student ASME group is thinking of restarting it.

 

I roll my foot as well rather than "heel-toe" I started off that way because true heel-toe just felt really awkward to me and couldn't get smooth, luckily the pedals are real close. I also trail brake and don't use the emergeny brake. trail braking is just done by holding your foot on the throttle and braking with left foot, what is does is shifts the weight of the car causing it to "rotate" through the corners better. Very very hard to do right as too much brake will cause understeer condition and too little makes you go too fast.

Ron

 

In an ideal racecar you won't have a clutch pedal for your left foot to deal with. Formula 1, WRC and competitive go-karting are a few places where left-foot braking technique has been proven as worthwhile.

Trail-braking is the same exact goal and methods. It's possible to be smoother when you are using both feet. Just like anything else, if you haven't done it much it will be clunky and less effective. When executed well it works well.

-s-

 

Not true at all. Trail braking and left foot braking have two very different and distinct goals.

The idea behind trail braking is to continue to use as much of the tire grip as possible during the transition from maximum braking to maximum cornering. This can be accomplished with either foot.

Left foot braking is used to control weight transfer front to rear without having to change the throttle input.

 

Most likely a bad idea. No offence. Left foot braking is used in two scenarios..

1. Dog box...jumping on the brake (leftfooft) in a threshold braking zone while the right foot blips the throttle to relieve pressure on the dogs that are engaged on the current gear...at the same time the blip speeds the gearbox up enough to engage in the lower gear without upseting the chassis. You would be amazed how many racedrivers get this very wrong and over rev the engine everytime.

2. Left foot braking midcorner is bad news everytime unless you are in very highspeed corner. It is much faster to commit at corner entry and be willing to drop two wheels at exit if things go bad. Braking midcorner actually transfers weight to the rear do to the torque effect between the axles and the rear brakes. The rear transfer ends in a more drastic push. If you want oversteer in midcorner...just lift the throttle.

 

Hate to sound like a "know it all" *sigh*

The term "heel and toe" came from truck drivers that had to downshift using their heel because the brake pedal was so much higher than the gas. They literally had to reach way over with their heel to hit the gas in order to blip the throttle. In modern cars, you brake with the ball of your foot and lean the right side of your foot over to blip the throttle. The most sensitive part of your foot to brake with is the ball underneath your large toe....just lean your pinkey toe over to blip.

 

the pedals that are shaped like barefeet work really well~!

 

You guys, ever since owning a car I have been trying this. I can't seem to apply and hold the correct brake pressure needed while blipping the throttle. Also hard to tell how much rpm needed so sometimes I under-rev and the car will nosedive when I release the clutch. I've just been practicing on a few turns here and there. But can never get it right.

 

I've found I can do it on the street, which sounds like what you are doing, but really it is harder than on the track, to me anyway. On the track you are basically 100% on the brakes all the time and when you blip the throttle you rev very high when you drop a gear, so you are at the extremes of each compared to trying to practice at about 30-50% with it constantly changing.

 

I have autovation pedals. I dont find myself hitting both pedals by accident like with cheap covers but they feel great all around otherwise.

 

On the street its hard to learn, however it can be dangerous/expensive to learn on the track (i.e. look for a certain Viper track video. It's labeled as a brake failure but the instructor said the student had a failed attempt at heel/toe ). I would suggest practicing when you slowing as you come off the freeway. This way you'll be applying more braking force than just on normal/slower streets.

As for how much to blip, you just need to practice more. You'll learn how much blip you need by the sound of the car the more you do it.

Also, another tool people can use are PC racing simulations (such as rFactor, the GTR series and GTL). The ones listed support clutches (and some other games do as well) and simulate the effects of heal/toe (and the lack of it) extremely well!

http://www.youtube.com/watch?v=rLrwTDUWjYg

 

One of my tall friends adapted by braking with his heel, and bliping the accelerator with his toe end. Opposite, but his legs wouldn't permit him to use the conventional method.

Whatever works, as long as you can control the brake and gas pedal, than its all good =p

 

In my opinion, at higher revs, it's actually easier to learn how to rev match and heel-toe. When you miss, you're going to feel it when the the car pulls itself up to the matching rpm. In that sense, its easier to grasp where the threshold is for accurate rev matching.

On the street, I would say that heel-toe braking is essential for any sort of spirited driving. We all share the roads with other people, so we have to be conscious of what might be around the corner. Heel-toe braking allows engine braking to slow down adequately, if you have to stop if there is something around a corner, but allows you to exit full blast at high rpm powerband if everything is all clear.

 

+1 on gaming simulations. I learned the balance of left foot braking to improve my lines in GT3/GT4. Since there is only gas and brake (no clutch) I couldn't practice toe-heel, but left foot braking feels so much smoother in game than not doing so.

 

Maybe I'm extra sensitive but I can feel the front dive/rise plenty at lower, 3000ish, rpms. If you have never done it no need to try and do it at 7000rpms and risk blowing your engine by down shifiting and reving to 9000 or so.

I've also never had a case on the street where I just needed to heel toe, even under spirited driving. But I also don't drive at 10/10ths when I'm driving spiritedly(is that a word??). Although it would be a good way to practice.

 

I've got a yield onto an onramp by my house which helps a lot for practicing heel & toe. I'm always bummed when there are too many cars in my way to try it. You can also practice at any slow corner 10-15mph turns. As far as practicing heel and toe on a pc, check out the G25 racing wheel by logitech paired with some of the games Mahjik was talking about. 300$ for a wheel is expensive but it's a lot cheaper than your car (has a clutch, 6sp gear box, and a leather wheel).

 

wow, the PC simulation I'm going to get. Just gotta find all that jazzy stuff

 

Eh, its just that with a ~2000 rpm difference between gears, I think its a lot easier to gauge the difference for rev matching. But whatever it takes for people to learn...

And while heel-toe technically isn't required for street driving, it sure is boring exiting a corner in a higher gear, at 3000 rpms rather than say, 2nd gear at 5-6k =P

 

While I feel learning heel&toe on the street is useful, you've got to keep in mind that on the track you'll be braking nearly 100%, which you won't be doing as you practice on the street. But it certainly helps to get familiar with it on the street.

Dave

 

The main difference being that when doing full braking, you have to move your heel less to use the same amount of throttle (because of the way the pedals are set up), while you also have to be more precise with the revs because when you're using full power and full braking, the chance you'll spin the rear wheels is much higher...

Either way, it's not something you can learn immediately on the track, so learning on the street is still important IMO...