dan_uk

yea realy we should settle this with a race I think

I tried skipping gears and not letting the clutch out at road atlanta last time and I didn't feel it stopped as well
Maybe I just like a bit more rear bias.. I don't think I am much good on the brakes realy

TTMartin

Probably time to close this thread.

WynnS123

Good idea!

robrob

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Minor point: It is more important to be correct than to use a larger font!

I'm not intentionally changing the font size. I'm getting font size 3 as I type this, I believe size 2 is normal, and I've had size 4 institute itself. I have to select the entire post and change it back to size 2. If I edit a post some of the quotes will auto change font too.

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There is too much inertia in the wheels and tires alone, not to mention the entire driveline, for the wheels to actually come to a full stop and resume full rolling speed with every cycle of the ABS. Do you realize how much damage that would do to your transmission and engine parts when ABS engaged at 100 MPH if that were actually true?

How long does it take to lock the wheels of a non-ABS car when you stomp the brakes? It's pretty quick. And when they're locked what's the driveline doing?

macr88

It's not going to do anything, ABS is preventing a speed differential. It's not 100 to 0 it's 100 to 90 or whatever the split happens to be.

ZDan

In both my Z and in my ABS-disabled S (on 225/245 R-comps), the fronts always lock before the rears (despite all the reports of rear bias on the s). The driveline being engaged should act somewhat like abs at the rears. Of course power from the brakes acting to stop the rear wheels will easily overwhelm the power of the engine at idle. But the additional effective rotating mass of the entire driveline will give the rears additional resistance to absolute dead-stopped lockup vs. the fronts. Anyway, I've locked the fronts numerous times, never the rears, which presumably would kill the engine, though if you leave the driveline engaged it should bump-start back to life when you modulate off the brakes and the rears spin up again.

Leaving the driveline engaged is and has been the standard technique and shouldn't have any negative effects on braking or on the driveline, with or without ABS.

TTMartin

I think there is a serious misunderstanding of how ABS works, or a blending of ABS and VSA concepts here.

ABS reduces braking pressure on a wheel that has impending lock up.

VSA works by braking a specific wheel in order to maintain directional stability.

In either case we are talking about a single wheel, and a Limit Slip Differential, not a NON Slip Differential. Locking one rear wheel, which neither ABS or VSA do anyway, transfers power to the other wheel.

Wiki: Anti-lock braking system

Howstuffworks: How Anti-Lock Brakes Work

jelanier

I applied what I learned here on my track day this Friday/Saturday at Road Atlanta. I made a few shift errors, but for the most part I stayed in gear in braking zones. It made it easier to downshift as well.

I improved by 3 seconds on my lap times. I still have lots of room for improvement. I coast a lot before T3 and the esses. I also brake too early for T1, T6 and T10a. I am still timid My previous best was 1:56. I got to 1:53. The car is stock except for the Carbotech XP10/XP8 pads.

The video is not very exciting. (5 laps 1:53.5,1:53,1:53,1:56,1:54)

Jim

http://www.youtube.com/watch?v=1-XpiyDP73A