Anti-Lock Brakes

Anti-lock brakes...and that's ABS...work mostly in the rain or snow. On dry pavement and with the wheels straight...a car will most often make a emergency stop without any wheel lock-up...and that's due to electronic-brake-balance along with modern tires.

But check out your anti-lock brakes with a drag-test to make sure they are not costing you. Drive by a sign on the Interstate at 70 MPH, then let the car coast down to 40 MPH, and note the distance the car coasted. Now take the fuse out of the ABS, repeat the drag-test, and see if the two coasting distances are the same...

Okay...put the fuse back in the ABS.

Reply to
PolicySpy
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Not if you have good brakes, good reflexes, and aren't afraid to give the brake pedal a good healthy shove. A car will stop a heck of a lot faster than most people have ever braked. If you're truly panic stopping, as in if you need to stop RIGHT NOW and don't know if you have enough space to do it but gosh darn it you're going to try, on dry asphalt and you don't feel the ABS kicking in (ASSuming an ABS-equipped car) you're not pushing hard enough.

Now, in a non-ABS car, the trick is to NOT lock up the wheels - because the coefficient of friction between tires and asphalt is significantly less when sliding as opposed to rolling - but to get as close to that point as you can without actually locking the tires. In practice what happens is a good driver will stab the pedal hard, then let off slightly when he feels the wheels starting to lock, but no more than necessary to keep 'em rolling. Only way to do that is practice...

nate

Reply to
Nate Nagel

Forgot to mention, getting a little OT... tires play a big role in braking performance. Some tires have so little traction that they are trivially easy to lock up, when braking not much more assertively than normal. GOOD tires will smash your eyeballs against the back of your glasses when you really mash the stop pedal. You ought to be able to panic stop at close to or above 1G on dry asphalt in a modern car with good tires.

Examples of the former category of tire that I've experienced would be the Goodyear Integritys that GM seems to put on everything, or the Continental all-seasons that came stock on my '02 GTI (why you'd equip a car with so much torque with such lousy tires I'll never understand - maybe the ease of doing big, smoky burnouts was a selling point?) or General Ameri-anythings. The latter category includes, in my experience, anything with Michelin Pilot on the sidewall...

nate

Reply to
Nate Nagel

Can I leave the fuse out of the ABS? It'a PITA...

Reply to
Hachiroku

ABS = the car is smarter than the driver :)

Reply to
gnu / linux

They will be the same. ABS is inactive during coasting.

Reply to
Ashton Crusher

Nate Nagel wrote:

No...electronic-brake-balance and modern tires...eliminates wheel lock up on dry pavement...when the wheels are pointed straight.

Now race cars have mechanical-brake-balance and no problem with wheel lock-up during a long, long, history of motorsports. In fact in setting up a race car...there is only brake size, rotor size, tire size, and mechanical-brake-balance. Well...a race car brakes the same way every time and only needs one brake-balance rather than a variable brake-balance of an electronic-brake-balance. But again...there can be uphills and downhills on a racetrack so the most modern race cars MIGHT have an electronic-brake-balance.

Reply to
PolicySpy

PolicySpy wrote:

Reply to
PolicySpy

Asht> They will be the same. ABS is 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.

Reply to
PolicySpy

I've been away from it for a long time, but contact your local SCCA Region and see if there is a Showroom=3Dstock driver you can talk to, maaybee you'll luch out and find one with a car like yours.

Reply to
SeaWoe

No, sorry. That is just not true.

ABS will prevent lock-up, not modern tires, not "electronic-brake-balance"

I don't think you even know whether "electronic-brake-balance" even exists.

Reply to
Alan Baker

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.

Reply to
S.Hansen

S Hans> You need to study ABS systems a bit harder. ABS may monitor the tire

And the ABS is also the stability control...

Reply to
PolicySpy

PolicySpy wrote:

With the correct amount of brake-balance...there is no wheel lock-up on dry pavement with the wheels pointed straight. (On most race cars there is no adjustment other than brake-balance. Now modern street cars have...electronic-brake-balance that reduces brake hydraulic pressure to the rear brakes as the brake pedal is pushed harder.)

ABS essentially unlocks a wheel that is locked-up. Well...a wheel approaching lock-up is turning slowly...and then the ABS kicks-in. So ABS most often works on slick roads or when emergency braking with the wheels turned...

Reply to
PolicySpy

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.

Reply to
PolicySpy

I'm sorry, but you're wrong.

No amount of "balance" can overcome the fact that the brakes of a modern automobile are powerful enough to lock the wheels.

...or with wheels straight.

Reply to
Alan Baker

Then you're not pushing on the brake pedal hard enough. (assuming you want to "panic stop.")

nate

Reply to
Nate Nagel

For a loose definition of "modern." It's quite possible to get wheel lockup in my '55 Stude with manual drum brakes. Very good manual drum brakes, but still.

*NOT* being able to lock the wheels on dry pavement is a sign that your brakes aren't good enough.

Nate

Reply to
Nate Nagel

Threshold braking is a lost art. I currently don't own a vehicle with ABS. The last vehicle I had with ABS spent the last 8 years of its existence with the ABS fuses (controller and pump) removed and with the warning light bulb removed. It stopped rather better than it did with ABS, and a LOT better than it did when the abs started throwing error codes.

Reply to
Steve

Not necessarily- that depends on the ABS implementation. Better ABS systems still have a mechanical proportioning valve assembly so that the front/rear bias is correct even without ABS. Only the low-end crap uses ABS as a hack-job approximation to brake balance.

Reply to
Steve

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