Anti-Lock Brakes

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On Mon, 27 Apr 2009 16:21:32 -0400, PolicySpy wrote:


Can I leave the fuse out of the ABS? It'a PITA...
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ABS = the car is smarter than the driver :)
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On Mon, 27 Apr 2009 20:29:22 -0700, gnu / linux wrote:

gnu/linux...which version?
I REALLY don't like ABS. It 'works' at odd times, like if the car hits a bump with the brakes applied, etc. it's a real pain.
I like to have more control over my car than my car has over me...
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wrote:

They will be the same. ABS is inactive during coasting.
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PolicySpy wrote:

Ashton Crusher wrote:

PolicySpy wrote:
ABS...MODULATION...is inactive during coasting. Hopefully the ABS system does not have any undesired characteristics on the baking system...when it is inacative. And if it does then decide if it is a characteristic of ABS or if it is a maintenance or repair problem.
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rotation but don't do a darn thing until you mash on the brakes. As cars get more complex, it will behoove you not to mess with the system. They are getting tied together to do more than abs.
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S Hanson wrote:

PolicySpy wrote:
The ABS is also the traction control. You could have a bad wheel-speed-sensor thinking that there was a small amount of wheelspin and thus applying a small amount of braking to a drive wheel.
And the ABS is also the stability control...
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I mean...the traction control and the stability control...share or depend on the mechanism of the ABS. And the traction control or the stability control could be applying a small amount of braking as a malfunction. Of course the ABS itself can only...modulate and that would be obvious if a malfunction.
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But IF there is a speed sensor error, it will throw a code and let you know. the engineers have put fail safes into the system. Do you have any idea the amount of checks that is done on a o2 sensor? More than you can imagine.. The same is applied to all aspects of the cars. IE GM uses 3 voltage reference on the electronic throttle position 0-5v, 5-0v and a mathematical difference between the two. If it sees a slight variation beyond the tolerance it sets a code and may go into failsafe. When you talk about Traction control and stability systems, your right the wheel speed sensor does play into it. But some cars have yaw sensors. WHAT IF IT IS FAILING!!!! OMG!!!! WHAT DO I DO!!!
Trust the system to inform you of a fault, it can and will do this.
Steve. ASE Master Tech, L1 Diagnosis Subaru Tech.
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S Hansen wrote:

No...cars are being found with brake drag with the ABS fuse in...that is eliminated with the ABS fuse out. And there are no error codes...
But in one case there is a feeling in the steering such that the problem probably is the traction control. And in fact in that case the traction control can light up...in normal driving...just showing a moment of useage but no error code.
I didn't say that before...I just here's an easy way to test for brake drag. And that's coasting distance from 70 MPH to 40 MPH...with the ABS fuse in and with the ABS fuse out.
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PolicySpy wrote:

On some models, brake drag may be caused by a defective windshield rain sensor.
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i must say, your partial grasp on abs and traction control systems is providing entertaining reading to a shop with 4 techs: 3 of them ASE master techs, 2 of them Subaru Senior Master Tech's and one turning wrenches for a lot of years.
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On Thu, 30 Apr 2009 10:55:31 -0700 (PDT), StephenH

The techs in my kid's shop (suspensions) mostly goof off by welding containers to hold liquid nitrogen for cooling chips on old PC's, and taping the overclocking benchmarks for Youtube. Different shops, different goof off procedures.
--Vic
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wrote:

LOL, reminds me of my AF days.., Liquid Oxygen...
With the recession, things are slow in the shop.....
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S.Hansen wrote:

Not only that, many ABS systems CAN'T do anything without foot pressure on the brake pedal, even if their control relay sticks and the pump motor runs constantly. Without the master cylinder being partly activated, all the pump can do is circulate fluid around.
It all depends on the PARTICULAR ABS implementation.
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I've been away from it for a long time, but contact your local SCCA Region and see if there is a Showroom=stock driver you can talk to, maaybee you'll luch out and find one with a car like yours.
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Well...this subject did not go well here. But I appreciate that everyone did just stick to the subject...
One last parting shot...
Old cars locked up their brakes because they were set up for even brake wear front to rear...and thus old cars had too much percentage of hydraulic force going to the rear brakes. And old cars also had narrow tires...
You shouldn't say that old cars locked up their brakes and then say that new cars should lock-up brakes even more. New cars lock up their brakes less...because they proportion front to rear hydraulic force and because they have wide tires.
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Old cars locked up their brakes because that's what brakes do.

What does the proportion of force between front and back have to do with locking the brakes up? If you apply enough force to the pad, the brake will lock up. It doesn't matter whether the front brakes get more or less force than the rear brakes.... get enough force and the brake will lock up.
And there are times... very few of them.... but there are times when locking up the brakes is the right thing to do. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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Scott Dorsey wrote:

PolicySpy wrote:
Cars of fifty years ago often became race cars. They had two master cylinders...one for the front wheels and one for the rear wheels...with a lateral rod connecting them together. Then one rod came from the brake pedal to the lateral rod. The lateral rod could be adjusted with a screwdriver to vary the proportion of hydraulic force going to front and rear brakes...and that just based on the leverage of the lateral rod. Also the master cylinder for the rear brakes was smaller than the master cylinder for the front brakes. Now the race cars of fifty years ago did not have a problem with brake lockup...
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Yes, but what does this have to do with anything? This is totally irrelevant to the subject of brake lockup. Why do you keep going on about proportion of braking force?

What is a "problem?" Cars of the fifties... you could lock their brakes up. Cars today without ABS... you can lock them up too.
In a racing situation there are a couple of different cases where locking your brakes up is a very important and useful thing to be able to do. There are a lot of other cases where you don't want to ever lock your brakes up. This is why skilled drivers are used, because they can make qualified decisions about proper braking under varying circumstances. --scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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