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ABS: Pump or Hold?

Dear Readers:



My '03 Cavalier 2DR 5 spd has ABS. I have read the owners manual and it says to HOLD the brake to the floor, because the ABS does the pumping action. My family says that ABS brakes are able to be “pumped” to slow the car down. Am I right that holding down the brake and letting the car do the work is correct, or should I be pumping them(regarding emergency stops)?



Sincerely,



Casey

Pumping ABS brakes entirely defeats their purpose. Just stomp the peddle as hard as necessary and try to drive around the obstruction. Your family is wrong on this one.

Congratulations on reading the manual. Follow the instructions. HOLD stead pressure on the brake pedal and let the ABS do its job. Your family is defeating the purpose of ABS by pumping, and their advice is incorrect.

The ABS pumps the brakes for you several times a second-- way faster than you can! No additional pumping is necessary.

First, I also want to congratulate you for reading the Owner’s Manual. Far too few people actually do that, much to the detriment of their car and their wallet.

That being said–Why would you assume that various family members know more than the people who designed and built the car?

Your family is wrong, wrong, wrong, and you would be very foolish to take their advice over that of the engineers who actually have the credentials to know how the car’s ABS system operates. When making an emergency stop, push the brake pedal firmly, as far as it will go, and allow the car’s braking system to operate as it was designed to.

Don’t pump,studies have shown that people don’t press the brake pedal hard enough in max stop situations.

By all means, apply what ever pressure you need and let the abs do the work. Some cars, mine, the abs doesn’t function at very low speeds…<5 mph. Rolling out of a steep drive in slippery conditions for example, may require a little pumping to retain steering.

Not only do I agree with the others 100%, I think it is time to stop listening to your family’s automotive advice. Good job reading the owner’s manual, which is the untimate authority on your particular car.

Some of us will read the instructions then try to do something else. Eclectic instruction can lead to mistakes. You never pumped brakes to slow the car down anyway. You used to have to pump them so the car wouldn’t go into a spin on slippery surfaces. (To maintain steering control too.) Now ABS takes care of it.

I agree with “hold.”

One additional question: since every time the ABS “pumps,” there’s a brief loss of braking, would there be any advantage to pushing JUST hard enough to get the ABS working vs. attempting to push the brake pedal through the floor?

ABS only kicks in when one or more of the tires skid. If the tires are skidding, there’s no point in applying more braking pressure. However, in an emergency, do you really want to risk trying to find the spot where ABS just starts to engage? Just romp it down like 99% of the driving public would do in a panic and let the system do the work.

The ABS may be activated because just one wheel is slipping. In that case, applying more pressure will help. It would add more braking effort to the three wheels that aren’t slipping. The #1 mistake that people make with ABS in an emergency is to back off on the brake pressure when it activates.

Like others have said, push hard. A number of makers are even adding systems to add extra ‘push’ when they sense the driver’s not pushing hard enough, called ‘brake assist’.

I believe that Abs works for several reasons;
The release of the brake allows the front wheels to free wheel slightly to regain steering.
Secondly, a fully locked wheel can, like an ice skate allow a water layer to build up encouraging less stopping friction.
Third, in snow, a rotating wheel allows snow to clear the tread where a locked wheel can clog the tread which deceases control and stopping.
In really wet snow while depressing the abs assisted brakes, you may feel the car actually maintain speed instead of stopping, which is quite alarming…it’s still working to stop you in a safer manner that you could on your own.
This discussion is really good, because getting your brain on board with abs function means there is a better chance you’ll use it correctly.

Dear repliers:

I have another question. My girlfriend states that older/newer ABS systems in different cars can act differently…is this true?? I guess I just want to get different opinions, and see if they match.

Yes, different cars have different systems which may seem slightly different. However, old or new, and no matter which car, the usage is the same. Press and hold, do not ever pump. Don’t reduce your pressure on the pedal when it modulates. If you’re close to hitting something, then push the pedal as hard as you can.

H O L D ! ! !

Pumping the brakes (on anything) is wrong to begin with.

You either “threshold” brake (hold the brakes just before the point of lockup) or you let technology do the work for you, in a vehicle with ABS, and simply put the brake pedal to the floor and let the ABS do the work.

Pumping the brakes is dangerous, and should NEVER be done.

Funny, I seem to recall being taught to “feather” the pedal in snowy conditions.

Not a binary “stomp/release,” but “press to lockup/back off just enough to get wheels rolling/press to lockup.”

Seems logical: if you don’t press to incipient lockup, you’ve no idea if you’re getting max performance; then, if you don’t periodically back off a bit, you have no steering.

I suppose that’d be the best bet an ANY case, but the last time I truly needed a panic stop (elk in the headlights), it was just a reflexive “stomp and pray,” to tell the truth.

(Note that I’m referring to non-ABS, BTW.)

Stomp, stay, steer.

Stomp on the brake, stay on the brake, steer around the object. (courtesy the psa that ran on MotorWeek for years).

Yes, different cars with ABS will probably have different technology, but even if that is the case, how the driver uses the ABS doesn’t change.

There may be differences in how different ABS systems act, but the whole point of ABS is that it can pump the brakes faster and more effectively than any human ever could. So if you pump ABS brakes, you are defeating the purpose of their existance, no matter which type of ABS system you have.