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Old July 28th, 2004, 08:30 AM   #1
dougmack
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Stopping Quickly on the track

When slowing down at the end of a long straight on an autocross course, I often find myself engaging the ABS. I'm now wondering whether it would be more effective to try to hold the braking just below the ABS threshold.

At Alameda, I got to ride with a really quick driver who muttered with some disappointment that he'd engaged the ABS towards the end of the braking zone at the end of the first long straight. It made me think.

In May, I took the 3-day Russell Racing course at Sears Point. They control speeds while you're learning the line and technique by controlling the rev limiter. They start with it really low (3K), so you're bumping into the rev limiter often. I quickly learned that I could go a bit faster by holding the engine just below the rev limiter threshold. Hitting the rev limiter seemed to slightly slow the car.

I'm wondering if the same is true for ABS. Any ideas?

Doug
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Old July 28th, 2004, 09:57 AM   #2
ar38070
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In theory

if you can brake at just below ABS activation then the car will stop quicker. In practice the difference is probably not that much. Braking under ABS theoretically will allow you to still turn the car if necessary. Theoretically at if the car is at maximum brake effort without ABS activation turning the car would not be possible. You could theoretically pump the brakes at maximum brake effort to allow you to turn the car but the skill level to do this is high. ABS makes us less skilled drivers look like we have better driving skills than we really do.


(It also keeps us from flat spotting tires.)
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Old July 28th, 2004, 09:58 AM   #3
EdSac
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ABS, to engage or not to engage

I've been told by two driving instructors to "stand on it" at the end of the straight. I don't like the feedback of the ABS, but I've been told to engage it.

I'd defer to Doug d, as I saw him tear up the autocross course our SVR PCA club had set up. Very smooth and fast.

What say you, Doug d?
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Old July 28th, 2004, 10:12 AM   #4
Mdreiver
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The fastest way to trim off speed is to engage ABS. There are still circumstances when you won't want to though. But any time when threshold braking is appropriate, you want to ultimately have ABS engaged.
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Old July 28th, 2004, 10:58 AM   #5
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ABS frustrates me too

I drive two other non abs cars, a 914 and a hopped up Echo, and I feel like I get better threshold braking than in the Boxster with those cars. I always seem to get early activation of ABS in the Boxster as well. Wish there was an easy way to dial in a little more agressive setting with abs. My Audi A4 seems to have better ABS modulation than the Boxster too. I have rarely activate abs in the Audi - although I activate Stability control program on a regular basis in the Audi and that can be irratating as well in a car that likes to plow.

I took the same Russell school as you. Great expereince. Those mazda's on the last day were the best. Talking about a car that lets you brake late! My best moment was when one of the instructors pulled the fast 3-4 of us in a group and he looked at my time and assumed a 21 year old kid with karting expereince set my time. Once he realized it was my time he said wow not bad. Thats good for a 42 year old guys ego and made my $2500 investment feel worthwhile! I was ready for F1 circuit, then reality set in!
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Old July 29th, 2004, 11:44 AM   #6
doug_d (Cameron Park, CA)
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such pressure...but since i've been called out, i'll throw in my 2 cents....

stand on it. if you've got abs, use it! as ar38070 said though, in practice, the difference probably isn't your biggest opportunity to go faster.

while maximizing the length of the straight and maximizing your speed along that straight are good things, i know that for me, the opportunity to lose time is a lot greater by entering, taking and exiting a corner wrong than it is to gain time by perfect braking.
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Old July 29th, 2004, 12:21 PM   #7
KenJ
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I spoke with that guy...

... the one DougMack rode with and he mentioned his concern for unsettling the car at a critical point. Smoothness and correct lines have been mentioned and that was his primary reason for grumbling at the end of the long straight - in his effort to get back on the throttle without the car still deciding whether it wants to skid a tiny bit (10-20 times) or allow a smooth weight transfer. He was trying to get all the ABS finished by the time he transitioned, but he blew it and was braking a bit too late.

He mentioned he should probably work on that.
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Old July 29th, 2004, 04:45 PM   #8
Docdanracy
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Talking Abs?

STAND ON IT!!
Only with ABS can you stop and steer the car at the same time. You can practice threshold braking until the cows come home and never be able to accomplish what the ABS does in an instant with out thinking about it.
After AXing with 3 flavors of 914 from mild to wild and 2 Carreras and 1 944 Turbo of my own I can say that the Boxster is the easiest to brake steer and accelerate.
By the By Ken, who was that masked instructor Doug Mac rode with anyway?
Was he a Boxster driver? Most of the Boxster drivers that I know that are experienced in the Box and instruct are comparatively smooth...if there is such a thing in AX.

Dan
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Old July 29th, 2004, 07:21 PM   #9
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For me I'd rather have the abs off and drive in manual mode. That way I'm making all of the inputs and learning what it takes to increase my cornering speeds.

Unless I was driving something with big horsepower, my strategy is to go in fast, which means being off the brakes before turn-in, getting on the gas before initiating my turn-in. Gentle throttle thru the turn to balance out the tires and then accelerate as I unwind the steering wheel.

I see a lot of overbraking into turns that lowers cornering speed and overall track times.

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Old July 29th, 2004, 08:27 PM   #10
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Exclamation Abs?

I believe we are talking about AX not big track driving. I agree that threshold braking is better on the big track but in AX the inputs are much more abrupt and aggressive. Almost violent if you will.
With that and the turns come much more quickly some times you need to use the braking action to help rotate the car, along with steering and gas input. In many instances I use the braking action to rotate the car in quick switch backs instead of the steering wheel to help avoid understeer.
Big track tech requires smooth inputs with the wheel, brakes and gas.
Driving on the big track or aggressive street driving require entirely different techniques from AX (if you want to do either well)
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