Leftfoot braking
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From: Fremont, CA
Car Info: STI and Outback Sport
Originally Posted by Lurk
I use left foot braking to "brake boost" to build boost while racing from a roll.
Looks like I need to practice pulsing. Makes sense now why it worked well for me in dirt and wet but not in the dry
JOhn
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From: UCIrvine
Car Info: '05 Crystal Grey Metallic WRX Sport Wagon
Originally Posted by scoobsport98
Is this for AWD? Wouldn't your rear tires have some accelerating force also? And can a tire be accelerating and decelerating at the same time?- (the .5g-.4g= .1g thing) Wouldn't the .5g acceleration go away once the brake is applied? This explaination kinda makes sense, but it's hard to understand and very possibly flawed in the physics behind it. I'm not sure how much physics the instructors really know- they do know how to drive, and have real-life experience- that's whats important.
From my knowledge of physics (BTW it's my major in college - And go ahead, call me a nerd
), the first thing that comes to mind is this:
Since the front brakes are doing most of the braking, it causes the front tires to 'stick' moreso than the rears, and under lateral acceleration (cornering), the rear tires are therefore more apt to deviate from the circular path and 'swing out,' following more or less the tangent to the circle.
The friction of your tires is the force that causes centripital acceleration (vector pointed toward center of circle). This force keeps you traveling in a circular path... so, since your front tires are experiencing more of this frictional force under braking, they can still follow the curve. Since the rears don't have enough of that frictional force, they lose traction and the rear of the car slides out.
This all follows the 'ball on a string' model, where if one swings a ball attached to a string in a circular path (think lasso), when released, the ball continues in a straight path, tangent to the curve. In this case, the tension in the string is the force causing the centripetal acceleration, keeping the ball from deviating from the circular path.
And since frictional forces are dependent on mass, weight transfer must also be a factor, as others have already noted. But...We'll save that lesson for another day.
Physics ain't so hard to understand now, is it?
From my knowledge of physics (BTW it's my major in college - And go ahead, call me a nerd
), the first thing that comes to mind is this: Since the front brakes are doing most of the braking, it causes the front tires to 'stick' moreso than the rears, and under lateral acceleration (cornering), the rear tires are therefore more apt to deviate from the circular path and 'swing out,' following more or less the tangent to the circle.
The friction of your tires is the force that causes centripital acceleration (vector pointed toward center of circle). This force keeps you traveling in a circular path... so, since your front tires are experiencing more of this frictional force under braking, they can still follow the curve. Since the rears don't have enough of that frictional force, they lose traction and the rear of the car slides out.
This all follows the 'ball on a string' model, where if one swings a ball attached to a string in a circular path (think lasso), when released, the ball continues in a straight path, tangent to the curve. In this case, the tension in the string is the force causing the centripetal acceleration, keeping the ball from deviating from the circular path.
And since frictional forces are dependent on mass, weight transfer must also be a factor, as others have already noted. But...We'll save that lesson for another day.
Physics ain't so hard to understand now, is it?
This is a better explaination of what I was trying to convey. The thing about the torque on the wheels contributes to this (and it's something I overlooked). However I contend that what matters most is the difference in friction between the front and rear tires. The fronts get more friction during LFBing because of the weight/load transfer, and because there is aproximatly no net torque on the wheels (braking torque~=driving torque. And the rears get less friction during LFBing because of both weight/load transfer and the fact that they are being driven somewhat. Together this lets the rears slide while the fronts stay tracking. I'm not a physics guy (biochem instead), so those of you that are please let me know if this sounds about right.
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