Hard braking engages Anti-Lock on dry pavement?

[NECorolla]

I had one of those looking off to the side of the highway and then look back to the front to see brake lights and the rear end of the car in front of me coming at me fast and furious, so I stomped on the brakes and I actually felt the anti-lock mechanism kick in along with the gear grinding sound that accompanies it.

I'm just wondering if this is normal on dry pavement? I know in my Tundra my brakes would lock up on dry pavement and I would be rewarded with a nice rubber on pavement brake screech.

Is this a concern? The vehicle stopped in time, but I think on dry pavement I want the wheels to just lock up. Is that old school?

[sienna1]

That's what an ABS system is designed to accomplish (prevent wheel lock-up).

[LeanBurn]

Old skool. I think of it as Assisted Braking while Steering.

If your wheels locked up you would lose the ability to steer while braking, and would just slide with the original direction of travel. By not locking up you wheels continue to roll allowing you to steer and avoid the obstacle.

[NECorolla]

Originally Posted by sienna1

That's what an ABS system is designed to accomplish (prevent wheel lock-up).

Ok, I was under the wrong impression that it would only engage when traction was an issue. Like with snow, ice, or sand.

I assume there have been studies on the braking effectiveness of locking up the brakes on dry pavement, versus ABS?

[AlaricD]

For almost any set of materials, the coefficient of sliding friction is much lower than the coefficient of starting friction. If you lock your brakes on dry pavement, potentially it'll take longer to stop than if you can modulate them to get to the point of sliding and then back off. Even if the ABS doesn't modulate fast enough to reduce the stopping distance appreciably, you do get the advantage that you retain the ability to steer.

In a panic situation like you had, traction WAS an issue! Also consider when someone goes into a panic and locks their brakes, and seeing themselves sliding towards the hazard don't realize that they should let go of the brake to regain steering control or at least be able to restore the lost traction and brake again, and instead just stomp even harder on the brake. ABS helps immensely in that case.

[shotgunjimmy]

Originally Posted by NECorolla

Ok, I was under the wrong impression that it would only engage when traction was an issue. Like with snow, ice, or sand.

I assume there have been studies on the braking effectiveness of locking up the brakes on dry pavement, versus ABS?

If your tires are locked up due to heavy braking, then traction IS an issue.

[SuperchargedMR2]

Originally Posted by LeanBurn

Old skool. I think of it as Assisted Braking while Steering.

If your wheels locked up you would lose the ability to steer while braking, and would just slide with the original direction of travel. By not locking up you wheels continue to roll allowing you to steer and avoid the obstacle.

+1

Just hit the brakes & steer where you need to go.

[OkSlim]

Originally Posted by NECorolla

Ok, I was under the wrong impression that it would only engage when traction was an issue. Like with snow, ice, or sand.

I assume there have been studies on the braking effectiveness of locking up the brakes on dry pavement, versus ABS?

Traction was an issue. You were on your brakes so hard they were about to lock up and start sliding.


That's how AbS works.

[flamedrgn]

thats what my car sounds like.

[dcam09]

Mine will do the same thing on dry pavement. It's normal in my opinion.

[rolla-XRS]

One other thing to consider. You're in Maine...which (like Ontario) is sitting pretty cold right now. Probably below 32F.

So if you're using All Season tires, their traction is reduced below 5C (I think that's about 40F). That's basic physics and why so many people invest in winter tire rubber compounds that are better suited to near freezing temperatures. If Maine uses salt on the roads, then this too will reduce traction.