On Mon, 27 Apr 2009 20:29:22 -0700, gnu / linux wrote:
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...
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.
You need to study ABS systems a bit harder. ABS may monitor the tire
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.
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...
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.
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.
ASE Master Tech,
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.
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.
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.
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.
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.
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
And there are times... very few of them.... but there are times when locking
up the brakes is the right thing to do.
"C'est un Nagra. C'est suisse, et tres, tres precis."
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
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.
"C'est un Nagra. C'est suisse, et tres, tres precis."
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.