ioTus

iTrader: (5)

WHY is it so easy to lock the brakes with your left foot?

Its not only in my rex, it happens in my mom's 98 honda accord ex too.

Any clues?

abeomid

because your left foot is used to dealing with clutch which is just a hard push. After enough practice with left foot, you will get used to it and it won't luck up anymore.

Project84

Yeah, its like the hand you write with. I'm left handed, so when I write, its feels so narural its almost unconscious, it just happens. If I try to write with my right hand, I have to put serious effort into each letter. Same with braking. You learn to brake with you right foot until its a reaction more than an effort.

MIKE-P-28

iTrader: (1)

So why do you want to use your left foot to brake?

abeomid

Left Foot Braking is mostly used in FWD cars. When u left foot brake u can keep the RPM's up and also load the front wheels so they have more grip and it unloads the rear wheels so u get more oversteer=less understeer since most of the FWD cars understeer.

In a RWD car the soul of LFB is to keep the RPM's in the desired powerband OR IF YOU HAVE A TURBO, keep the boost up.

LFB is mostly used in Road racing (SoloI, GT, etc.).

Project84

Whats the difference between SoloI and SoloII? I don't want to hijack this thread or anything, but I thought that since you brought it up you know what it is and can tell me.

Defprun

Yeah, i was watching these guys racing in a Skyline GT-R and two AE86's and all three were using their right foot too brake...One guy would actually use the heel on his right foot to give the car gas blips to keep his lower powered trueno some revs in the turns.

abeomid

SoloI is mostly on track and higher speeds and the turn radius are larger.

SoloII is usually pylons set on a parking lot or an airport runway and has lower speed the the turn radius are generally smaller.


Heal/toe is used when the person is downshifting to matches the revs of the lower gear (higher ratio) so the car doesn't jerk when he lets go of the clutch. It was also used in older cars in which the transmission did not have any synchros.

peejay

Don't confuse heel/toe with double clutching! Heeltoe has nothing to do with the tranny having synchros or not.

FWIW, I had to learn to LFB with my Subaru... Subaru brake pedals are really soft and squishy even when everything's in perfect order, and the brake would squish halfway to the floor under heavy braking. Not very easy to blip the throttle for a downshift unless you have Bergeson joints in your ankle! So I would just brake with my left foot and downshift without the clutch. (Oh yeah, I also learned to shift clutchless in that car too )

LFB is traditionally braking and holding throttle at the same time. In a FWD, it's like grabbing the handbrake. (Some autocrossers just hold the throttle to the floor and LFB to control speed... ) The rear brakes work but the front brakes and the power application cancel out. It's like adjusting the brake bias with the throttle pedal.

It also came in handy on my first RX-7. The problem with drum brakes is that they lock easily due to the self-actuation effect of the shoes. Not a good thing to lock a rear wheel when braking deep into a corner. A little throttle negates that effect.

Defprun

Could be that he was matching revs...but the GT-R wasnt! How come?

The guy in the AE86 would kinda hit the gas a couple times, is that how you would match revs?

peejay

You match revs by revving the engine up to the speed that it will be at in the next gear.

Let's make a simple example. Car has a 2-speed transmission, first gear is 2:1 and second is 1:1. (Simple)

You're in 2nd gear, 3000rpm, and you want to downshift smoothly into 1st. At that speed, 1st gear would have the engine turning 6000rpm. To downshift smoothly, you blip the throttle to rev the engine up to 6000 before letting off the clutch in 1st gear.

Three points:

In the real world, you just have to get a feel for how quickly your engine revs and the space between gear ratios. If you sit there watching the tach and trying to get the engine speed right you will never shift. Takes practice. The little double-hit that you mention the one driver doing could be just the way he's found to get the revs right - he knows "if I tap the throttle just so, twice, then revs will be right". I do this, it's easier than one longer blip.

If you can match revs well, you don't need the clutch at all. Slip the trans into Neutral, rev the engine up to the appropriate RPM for the next gear, and the lever will just fall into place. Double-clutching is similar - you let the clutch out in Neutral and rev the engine up to get the transmission's internals spinning up to the new speed. Then you push the clutch in, shift into the next gear, and let off the clutch again. Synchronizers get the trans internals up to speed for you, which is why you do not need to double-clutch a trans with operable synchros.

Heel-toe downshifting is braking while simultaneously revving the engine to rev-match the downshift. Heel-toe is kind of a bad term since in modern cars you use the ball of your right foot on the brake, and rotate your ankle to hit the gas pedal with the other side of your shoe's sole.

Now that you know what all the terms are, just imagine doing a proper double-declutch downshift while braking... one of the most complicated dances in the world

Defprun

A dubble de-clutch whazzatwhazzit?! I'm not even gonna ask!!!

Is the engine always spinning in the lower gear(in this case its fitting ) at exactly twice the speed of the gear your are already in?

Project84

To learn about double clutching, click here

Its long, so order a pizza or some wings or something, use the bathroom before we get on the (information)highway, buckle up and go!!

As for the engine always spinning at twice the rpm as the gear you are going into, the answer is no. He was just using even numbers to make the explaination more understandable.