went from a 48.6xx on my first run, to a 47.017 (+1, errr ) on my last run.
But still, got the back end to come around, when I needed to. It was like driving a go kart in terms of how quickly the car stops, compared to when I use my right foot.

I think this year, I'll focus on left foot braking a bit more.

Please explain "trail braking". Thanks!

 

Can u explain a little about left foot braking? Thanks!

 

Left Foot Braking
In Front Wheel Drive

Theory:

When driven under acceleration with no brakes applied, a front wheel drive car will understeer when the front wheels are turned. To overcome the understeer, a technique called left foot braking is used to change brake bias (balance) to the rear. By using a combination of throttle and brake you can change from understeer to neutralsteer to oversteer. How does it work? Read on!

Weight Transfer:

Think about this for a second. When you stand on the throttle, which way does your body try to go? Toward the rear wheels! Right? Now what happens when you brake? Your body tried to go forward! This boys and girls is weight transfer! By using the basic rules of weight transfer and a combination of throttle and left foot braking, you can be in control when the unexpected happens on a rally (which always happens)

How Does It Work?

Brake bias in normal street cars is toward the front wheels for safety reasons. If you have ever pulled up your hand brake when turning on a wet road and spun out, you know why they build cars this way. What you did was bias the brakes to the rear, and this is not what Grandma wants in her Buick coming home from the supermarket. But as rally drivers we can use a means of biasing the brakes to the rear. Some of the things that can be done include using a brake bias control valve or installing more powerful brakes on the rear wheels. That works wonderful on a track, but on a rally it's hard to change your brake bias in the middle of a turn that suddenly changes from dry dirt with good grip, to wet slime with no grip.

Enter Left Foot Braking!

Once your have mastered LFB, when the road surface changes, you can change the brake bias by either adding power or brake pressure ( this is also called "modulating"). Example: You are in a turn and the rear of the car starts to slide out more then you want. You could release some brake pressure and increase the throttle. This will change the oversteer to understeer. The reverse is also true. If the turn tightened, you can change to oversteer by increasing brake pressure against the throttle. Also by balancing the brake and throttle you can get a neutralsteer.

Why Does It Work?

A tire has 100% of it's possible traction when it is rolling straight with no braking or acceleration. When you change any of these factors the tires affected will have less available traction and break loose earlier.By applying brake against the throttle in a front wheel drive car, two things happen. One: The front wheels keep turning. And two: The rear wheels try to lock up. If you are in a turn, the back of the car will start to slide toward the outside of the turn. To control or stop the slide, apply less brake and more power ( this changes the oversteer toward understeer and stops the rear wheels from sliding toward the outside of the turn ).

Putting Theory Into Practice:

Let's Give It A Try: Now comes the fun part, driving the car. Find a safe place to practice, a gravel parking lot with no trees will do.( If you live up north and it's Winter, try a frozen lake, this is ideal because everything happens at low speed ). Set up some traffic cones to make a Tee intersection. Now get in your car and practice driving the turn without left foot braking, but try doing the normal braking with your left foot.(What did he say??) Yes, try braking with your left foot! You can't learn to LFB until you train your left leg to brake! If you have never tried using your left leg, your will find it's like trying to write with your left hand if you are right handed. This is very important. Until you can drive doing the braking with your left leg, you can't do LFB. Once you can brake with your left leg, now let's try something new. First think about what you want to do, then start your practice turn. After turning in, apply the brake against the thr

 

Jeff.. where did you get that info from?

 

http://www.rallyracingnews.com/lfb.html

google!

 

 

All I have to comment is:

Are you sure this will work on pavement?

 

hehehe...maybe....slick surface?
search google.com for left foot braking FWD

 

I am sure it will. You may need to use a little more brake then they suggest in this article because of the greater grip developed on pavement by the rear tires. This can also be function of speed so when you're practicing experiment with different speeds. In my experience, FWD cars that are set up to oversteer at low speeds (such as those encountered at an autox) will oversteer a little quicker at higher speeds. So for a higher speed turn you may need to apply less brake then you would during a low speed turn. Again, this will take some practice to perfect (I'm not that close), but is a very useful skillfor performance driving a FWD car.

NOTE : Another advantage to LFB - If you have a turbo car being on the brake while your on the gas in a turn allows the turbo to stay spooled up so there will be less lag when you finally get back into the straight.

 

How can the engine accelerate to spool the turbo when the brakes are slowing the wheels?

 

not so much accelerate the motor, but increase the load on it, which will reduce the lag (correct?)

Brian

 

Yes, you put a load on the motor and give it a nice open intake path of air when you crack the throttle butterfly open. Keep in mind that in a turbo car, the intake manifold is under positive pressure under boost. Thus, you have no vacuum to feed your brake booster. It's easy to ruin out the booster vacuum, resulting in brakes that are much more difficult to apply. In the WRX, it can KICK the pedal into your foot when it happens.

 

i am sure u guys will break ur axles

 

Jeff...I wish I could have used Left Foot Braking at the autocross...but I needed my left leg to brace myself against the door.

Here is what I did to get my car to rotate around:
Car setup -
2001 Type-R
stock suspension
205-50/15 Falken Azenis
tire pressure at 39F/39R warm pressures
stock alignment, front and rear tow out, at service limit

I found that the car would plow into some of the corners, when I would reduce the throttle input as I was at the corner entrance the car would nicely rotate the rear end out, then increase the throttle and I could complete the corner on the line that I wanted. I thought that the car handled quite well throughout the autocross.

My times for the day were:
45.369
45.392 +1(a little too much understeer in 1 corner)
44.912 w/passenger and the sun finally came out
44.610 w/passenger and the sun finally came out

Hopefully I'll have some videos of the first 2 runs of the day...damn video camera didn't work on the last 2 runs

Austin

 

left foot braking most definately works on pavement. the majority of our race cars have dog-tooth gear boxes meaning that no clutch is need for shifting. due to this, ALL of the braking is done with the left foot. i've gotten so used to it, that even in cars with a street-derived gearbox, i left-foot brake whenever i don't need to downshift. when you've gotten good at it, you can be much smoother under braking and carry more speed into the corners. the concept is that if you're braking with your left foot, your right foot can continue to modulate the gas pedal--eliminating the "dive" that a car expiriences when you lift completely off the throttle.

 

This is a great thread. Thanks for all the info people.