M758

I once had situation fo glazed pads. In a pratice session and tried to make pass on slower car in tight 180 corner. Got to the inside and on brakes. Should have been a no brainer.. Alas the car did not slow. As I saw his driver door get closer I know I could not stop nor turn. So I dumped the clutch in 2nd gear. That broke the backend loose and she roated around and I made the pass and drove away without incident. Next lap I can in swapped pads. Not fun I can stay that, but it is amazing what you can use to slow down when you have no brakes.

Professor Helmüt Tester

Back to the original question - as Z-Man suggested, the driver is probably trying to induce additional rotation on entry. Yes, it unsettles the car, but you can use it to get a pushy car to rotate, without actually 'braking' too much.

If you've ever done any ice racing, you'll know that this is a common technique. Also a great technique on pavement, especially in FWD in the rain. I even do it in RWD race cars in the rain. I may be a putz most of the time, but I will boast that I'm freakin 'Rocket-Boy' on a wet race track.

RedlineMan

Hey All;

I guess there could be a few reasons why someone would brake like that.

- Maybe a needlessly spastic attempt to pump the brakes?
- Maybe solving knock back?
- Cadence braking (replication of ABS) is done this way. Don't know why he would need to though?
- Heavy and repeated front weight shift?

I myself found the Stab & Steer method pretty effective at Lime Rock this September. After 5 days of rain, the track was totally green, and there was no grip in Big Bend for me. I kept the throttle down and found that if I dabbed the brakes with my left foot every time the front started to wash out, I could transfer enough weight to get front grip, and carry much more speed than I could otherwise.

I also have been a pre brake zone tapper for years. Having gone into The 90 at Watkins Glen and had the pedal go to the carpet some years ago sort of put me in that habit. Fortunately my car does not go as fast as a Viper!!! People always ask why I'm doing that. When I explain, they quickly see the wisdom behind it!!

As for Viper man, I don't think there was much he could have done. The one thing he did do was go in fairly straight. Whether this was on purpose or not, it is the absolute BEST way to hit anything without doubt!

By the way, if you lose your brakes going into Roller Coaster, ease it LEFT!!!!

LS7-Kevin

Not a fun way to end a weekend.

Another Brake Fail Story-
I was in SCCA driver's school at Great Southwest Airport (Dallas Area). At about 140 I let off, stabbed the brakes, and thought the throttle was stuck open. Fortunately, the "escape road" (one of the old runways) was dead ahead and was able to negotiate it. Turned out, I had lost the front system of the master cylinder. Never will forget the "pucker factor".

P.Po

Gumball, perhaps you and Dave are speaking about different things. I believe Dave is talking about a system where each caliper gets connected to a seperate bleeder. Fluid travels from the Master Cylinder to the Caliper, to the self bleeder and back to the Master Cylinder again. This system is used to help keep fluid cool, air free, and circulating. It was very well described in a Panorama issue sometime this year.

-Patrick

Carrera51

Regarding the original question. Billy Bob said the brake lights were blinking about every 1/4 second. Is it even possible for most humans to pump a brake pedal that fast? Maybe the brake lights on the car were wired to rapidly blink when the brakes are applied (like I have seen on some motorcycles).

My guess is that the driver was left foot braking while still applying the gas with the right, in order to rotate the rear end a little.

ScottMellor

Going back to the Viper wreck.
Question:
Why would you yank on the handbrake to get the car spinning?
You could possibly go off the track and dig into the dirt and start rolling.
(Thanks for the tip about grabbing your harness prior to impact.)

M758

IF... you have an asphalt run off getting the car sideways will force it so slide and the tires will grip asphault sideways much better than rolling tire. This way you can slow down faster.

Gravel traps are nice, but asphalt traps are much better for this reason. They can dissipate energy with much less risk of roll over. Plus easier cleanup.

Alan Herod

I have not been able to view the video regarding the Viper crash and one of the subsequent posts mentioned the back straight at VIR, 170? In SCCA I think I experienced every type of brake failure possible. Fortunately, back in that day the car would barely go half that fast and had no where near as much energy. I know this is not very macho; but, as an instructor, having a personal speed limit is a good idea, particularly with very inexperienced students.

DGaunt

Gumball:

Not true. Nascar cars use this system on road course to help prevent brake fluid boiling in the calipers. The purged fluid goes to a catch can. differnt system than what you are talking about. I made the leap that if the good ol' boys figured that out, perhaps the application was braoder. Could be wrong.

Professor Helmüt Tester

Some clarity here - the circle track guys use a 'brake fluid recirculation' system, not a 'total loss' fluid change system. On short tracks, their brakes take a beating and some of the brake manufacturers developed the recirculators to try and cure the problem. It doesn't dump it into a catch can, but rather it's a closed-loop system that has check valves to allow the some volume of fluid to return to the system on the pedal return stroke. Tilton used to/may still make the key pieces, along with a bunch of other vendors.

I have some experience with brake fluid recirculators on race cars, and they are an evil, wicked pain in the ***. Nearly twice the plumbing, and a bunch more stuff to go bad. Stay away. If you think you need something like this, you're using the brakes waaaay too much. Middle pedal = bad lap times.

fatbillybob

carrara 51,

No the video I saw was a japanese jgtc race driver in a nismo skyline. It showed a view down the track that the driver would see and a picture in a picture of what his feet did. It was very cool. And yes on the approach to a braking zone instead of a full progressive threshold brake/shift/trailbrake/gas, he pulsed the brakes about 4 times in a second or two... heeltoe downshifted and gas through the apex. The skyline is 4wd.

DGaunt

I stand to be corrected Prof. Helmut. I was repeating bad info I guess. I agree that if you need this on a street car, you either over-built the engine, or need more instruction.

However, the purpose of the thread was to explain the driver's actions entering the corner. do you have a comment on that?

Professor Helmüt Tester

Dave - see my post on 11\01 at 10:46pm, above.

I haven't seen the clip, but I would bet money that he was rotating the car with the brakes, like the Scowhegans in Rally introduced us to in the 60's - stand on the gas and rap on the brakes to break the back end loose.

I 'ice race', in addition to road race. That's what you do on a frozen lake, sliding around at 100+mph, to get the car to turn. I also do it in the rain on road courses - to induce rotation and to settle the chassis - in fwd and rwd cars...even in rear-engined, rear-wheel drive cars. Seems natural, and it works well.

DGaunt

Helmut, I read your post of 5:26 and still wonder, why would he rapidly pulse rather than just a quick stab to loosen the car. seems tricky to induce rotation that way. Surely you want a fast weight transfer forward to loosen the car and then catch the rotation at the right point. I understand the technique you describe, but I am not convinced this is what he was doing. I AM convinced he was doing something tho....