Left-foot brake checking; do you?

Just to expand on a topic that started in the Mark Pombo crash thread on RRAX; how many of you guys do the left-foot brake test going into heavy braking zones? I never have, mainly because I questioned its usefulness. I always figured that by the time you realize something is wrong, and react, you're probably going to be around the same point on the track where you would have been going to brakes anyway. Also, since you're just tapping the brakes, I figured you probably wouldn't notice a failure that would occur under heavy braking. But, as is often the case, I'm probably wrong...

So how about it? How many of you test your brakes, and of those how many have found a problem in time to take a different course of action than you would have had you not checked them?

Almost always. Been there, almost did that.

On edit: to clarify, there's no way that a left foot tap is going to discover an imminent failure of a major component, such as a brake line or caliper; something like that is catastrophic. However, I developed a habit of left foot tapping from the old Showroom Stock days, when pad pushback, melted stock pads, and not enough brake fluid for the amount of pad travel was common. I wanted assurance that when I hit the brakes I at least had the beginnings of a good hydraulic system.

Don't jump to conclusions on the Pombo incident. I've seen exactly ZERO technical analysis on what happened, but I'd not be surprised to learn that the hydraulic system was fine...

I confess "no." I've always had relatively slow cars with relatively robust brakes - at least since we ditched the SSA Mazda MX6 Turbo in 1988.

K

I go through a lot of trouble to have very "free" calipers, both for the VWs and the SM cars. The amount of play in the bearings, flex, etc. will push rhe pads back, creating a long pedal. tapping the pedal will reduce the pads clearance.
The SM needs some LFB to turn in sometimes, as do the Big TA /ASA cars. They are so pushy that they will not turn in without trailing brake.( they are pushy to take more power mid turn out). The trailing brake is LFB, as the right foot is part way down and the trans is no clutch .( not SM)
The locked diff VW sometimes needs the LFB to decrease the turn arc, reducing power will just go straight . So there are times when you have some power and some brake on, esp. in the rain.
MM
So yes. I use LFB and teach it for advanced racers

Yes, I LFB too. my old brake setup didn't require it, but this one does so I have plenty of pedal going into the hard braking zones. the issue for me is consistency. if I don't pump the pedal a couple times before I nail the brakes, the pedal *can* be quite long, which provides for uncertain braking points as you're trying to find the happy place in the pedal travel without locking the front end or driving off the end of the track.

There is a difference between a tap to set the pads and make there is a pedal and full on pumping....as Greg notes.

On my car, yes, after a few laps I'm tapping withthe left to set the pad on the rotor and help with pedal feell, and near the end of races at VIR and CMP, I may have to actively pump the pedal up some.

With my Prelude only sometimes do I find it necessary (main straight at Summit Point for example). In the Miata, I didn't until the brake went MUCH further down than I anticipated at LRP. It's worth a little tap to set the pads, plus if I don't feel much there I can better prepare.

In my MK1 Scirocco yes, since the rules required solid rotors and solid front rotors excel at getting high spots in the them that knock the pad back, creating a long pedal.

In my Baby Grand, no need as you have to left foot brake that car so that you can keep the engine (which comes into the powerband at 6k and redlines at 13k) spooled up. Plus the Baby Grand has real modern brakes with large air duct bring air to them to cool them properly.

YMMV.

cheers
dave parker

I started doing it for big brake zones, but not sure if it would really detect an issue. As Greg said, if something is going to catastrophically fail then it probably won't happen till you jump on the brakes hard, which a tap isn't going to achieve. It does let you know the brakes are there and what kind of pedal you have. In that respect it instills some confidence. And if you have some sort of hydraulic leak then you'll know before you jump on the brakes hard.

David

I tap the brakes before entering every heavy braking zone, and at the end of the race, almost every braking zone in general, all using my left foot. I eventually started just Left foot braking on accident. If I don't have to shift, there is no reason to tap the brakes with my Left foot, then actually brake with my Right foot a few seconds later, so I just started keeping my Left foot over the brake pedal after I checked the brakes. I first did this entering the chute at Summit Point (on accident) I figure if everything turned out fine then, it should be fine anywhere else.

Steven

I learned the exciting way at NJMP that anytime I hit a curb, my S2000's pads rattle back. That got me in the habit of doing a quick double-pump anytime I even suspect I've rolled over a curb. That, in turn, evolved into the same habit on any long-straight-into-braking-zone.

I discovered the usefuleness of tapping the brakes before heavy braking zones at Grattan last summer. The CRX (and maybe Honda's to a certain extent) are not so great on master cylinder displacement especially as your pads start to get worn down. I ended up having pads at roughly half life before the race started and while racing into turn 8 following a sweeping up and down straight the brake pedal punched to the floor.

Ultimately the brake pads had bumped out a bit and the master cylinder had run out of stroke to get the pads back to the rotor and apply sufficient force. Now at the end of every straight I double pump the brakes to make sure I have the pads to the rotors before I go inot heavy braking.

To date I have done this with my right foot basically tapping the pedal lifting and then punching the pedal for my braking zone. I have always just done this because I am used to right foot braking and I need my left foot to operate the clutch to shift. I can see a case though for using the left foot a little before the braking zone just to keep the right foot firmly planted on the acclerator.

Another path I am looking down is taking some used up brake pads, maching off the remianing brake pad material, and using the backing plate as a spacer to help with the pedal feel on the Honda. As the brake pads wear I notice a large change in the brake pedal travel verse fresh pads. Thinking that if I place a spacer in at roughly half wear that should help the pedal feel better during the later life of the brake pads. This also provides more surface area to heat sink to as the brake pads get thinner.

Interesting replies. I had forgotten all about the issue some cars have with pad push back, so pumping makes perfect sense if that is happening. I guess I'm kind of spoiled, driving a modern car (only 22 years old :D) that has decent brakes and a big enough reservoir. I'm also pretty anal about changing pads & rotors when the pads are 50% gone, so my biggest concern is a catastrophic failure.

That said, I can't really see any down side to checking the pedal. It's probably a good habit to get into; who knows, maybe some day I'll get the chance to take a Honda out for a spin ;)

I'm just not able to pull off the physical aspect of heel toe, so I do left foot brake. I've had pedal's go to the floor in the Fiat, and the Honda had a pad fuse to the caliper piston, causing me to lap VIR with out brakes.

So yes, I have pumped brakes with my left foot. For what it was.

in the 944 I never felt the need, but in the 300ZX I am going to have to start. Last years ARRC, lap 1, in a freight train going in to turn ten, the pedal went straight to the floor making any kind of downshifting impossible, resulting in a forced spin and resultant loss of 4th place. Not that it wouild have mattered, since the ignition packed it in anyway...

I did it once to see if it made any difference to correct for pad knock back. What I found was that that tap exhausted the vacuum in the booster and since there is no vacuum at WOT it took more effort to stop the car.

In my ITA car (Honda Civic) I always left foot "tap" the brakes on long straights due to pad kick back. Not heavy though..just enough to make sure I have a good solid pedal before the braking zone.

The only other time I will left foot brake is in the T1 car. If a small amount brake is needed (mostly to settle the car) I will apply left foot brake. The worst thing you can do in a big horsepower car is snap of the gas when lightly braking and then slam back on the power.

Other than that I usually do not left foot brake.

My first thought was that it could also be useful for throwing off anyone on your tail possibly causing them to brake early. But the more I think about it, it would just invite a pass attempt even more. Unless you're already in traffic...

Thus the term "brake checking". Not really a way to win friends. I know that after a few I'd just accidentally hit ya. ;)