Dan GSR

Is left foot braking bad for your clutch?

I'm new to this left foot thing, so please bear with me.

I was practicing some left foot braking in traffic, I was bored.

It came to me.... if I'm braking hard, and gassing it....something has to give way?

wouldn't the clutch just spin? or put extra wear?

like at near dead stop speeds...im stomping on the brake, and trying to keep the revs up...is when this thought came into my head

thanks...


[Modified by Dan GSR, 11:13 AM 4/2/2003]

allenp

A typical minimum torque capacity for an OEM clutch is somewhere around 1.4x maximum engine torque. So there's no way the clutch is slipping unless it's severly worn, especially low RPMs where you're making very little torque anyway.

The only thing you're wearing is the brakes, as they are fighting the engine torque.

davidnyc

i believe you are correct in your assumptions, somewhat. But...

I use left foot braking as a means to rotate the car, not as a means to keep the rev's up or keep the car in boost, if I had a turbo car.

If I am entering a turn and the back of the car is unweighted, tapping the brakes can cause the rears to lock slightly, therefore causing rotation. But, I have not perfected the technique.


[Modified by davidnyc, 11:42 AM 4/2/2003]

Knestis

Sounds like you might be the victim of some bad info RE: left-foot braking. LFB is used (a) when you just need to slow down for a corner without downshifting, or (b) when you want to dramatically change the direciton the car is pointing (e.g., inducing oversteer on a loose surface or at high speeds on paved roads - danger!). You wouldn't ever be on the throttle in situation (a) and - I hope - you weren't trying for option (b) in traffic.* What "gives way" in situation (b) is the relative grip at the back end of the car and the front brake pads, which are trying to slow wheel rotation against the power of the engine.

I guess I would ask what you want LFB to do for you?

Kirk

*Ignoring the turbo lag stuff

JohnEX

if you're not on the throttle, then why left foot brake?

JeffS

One reason would be to get back on the gas faster.

phat-S

"Ask NOT what LFB can do for you reathah what you can do for LFB." - sorry, Kirk started it

Why? I'll sometimes hover w/ my left in a race start but definately where there is a section of track that req's braking but no gear change (RA T7, OakTree, CMP T5 - and sometimes T8 if I keep it in 4th, LMS T3b), it just seems logical to use that foot that is doing nothing at the moment. I have tried tapping the brake w/ the left mid turn to affect a change but never the luck/effect like I did w/ the 944 doing hte same (that **** really seems to work dramatically there, on the Rex, it just seems to slow the car \/)

Hracer

This could be a popular misperception about LFB, but anytime you are in gear, you can't really "keep the revs up" while braking. While in a gear, your revs are a function of speed. They will rise if you speed up and drop if you slow down, regardless of the foot that you are braking with, or even if you are on the brakes at all.

Lo-Buck EF

well, since were on the topic of LFB, i have a question regarding application of the pedal for rotation. when do u get on the brakes (with the left foot) to get the rear to rotate? i could never get this to work for me. so i end up lifting to rotate the car. but if i could do it while on throttle it would help cary speed. and i need all the help i can in that department.

-spenc
ps-dan. sorry to thread jack

Dan GSR

No...i wasn't trying to be an *** on public roads...it was bumper to bumper...i was trying to build up my left foot's sensitivity

CRX Lee

If you have the unpleasant situation that you are trying to performance drive an automatic transmission, left foot braking will not only let you keep the revs up but also keep the torque converter loaded and spinning at maximum multiplications and less lag for it to wind up again. If you autocross an automatic, LFB is a big gainer. Also if you have a turbo car and want to keep your boost up pressure up when otherwise the car needs to slow and lifting from the throttle would let the boost drop thus causing you to have to wait for it to spool up again.

Also left foot braking can be a good thing if you are driving a car with a loose suspension and keeping the driveline would up a bit can reduce the amount of excess body motion. If each of these cases you are not ever really trying to slow the car that greatly while keeping the throttle open but using the brake pedal lightly to help achieve or maintain a balance of the chassis.

Track rat

Quote:

"you can't really "keep the revs up" while braking."

True, but you can eliminate some of the mechanical delay associated with getting your foot back on the throttle, getting the throttle plate open again, getting the air moving into the motor again....etc.

I find LFB very effective in places where I need just a little deceleration, or just a little forward weight transfer. For example #5a at VIR, or between #16 - 17 at VIR. In those cases, the throttle foot stays planted. With more aggressive LFB, like #4 at VIR I lift off the gas.

Rodney

i started LFB midway through last year. LFB keeps the chassis settled, and allows minimal lag between getting on the throttle and brakes. In autocross, every milisecond counts, so as long as the course doesn't require multiple downshifts/upshifts (bmwcca comes to mind for this), you can be assured my left foot is hovering over the brake pedal. it takes some time getting used to, but i am getting quite good at it, even with my minimal use. at first i was flatspotting tires, but since i first tried it, my foot has gained much needed sensitivity. come to think of it, i used LFB before the main straight on limerock too.

ZUL8R

LFB

mos

I've read (on HT probably) that you can think of left foot braking as 'adjusting your brake bias rearward on the fly.' As you push the brakes and gas together, the gas cancels out some of the front brake, but none of the rear brake force is being cancelled. Other than rotating the car (on an FF non-auto non-turbo), I cant think of a reason to do this??

I guess if you're after those fractions of a second that it takes to move your foot over it may help.


[Modified by mos, 10:44 AM 4/4/2003]

Lo-Buck EF

yea rodney, ive watched your runs and u lfb like a mad man. im gonna take another stab at it this season. see if i cant use it affectivally(sp)