I was under the impression that having ABS will improve your stoping distance. I know that it will help during a breaking/skid keeping the car in more of a straight line (especially on wet roads) --- but while I was at a Mazda dealer dissusing my next car, he said"having ABS would make the car take a longer distance to stop"

OK, I need you guys (who know more that I do) to tell me what is true!

Thanks!

There are a great number of factors to consider, not the least of which (it will likely be argued) is driver skill. The other major factor will be road conditions.

For my two cents worth though, I'll keep it simple: if the anti-skid is inoperative on an Airbus A320 jet airliner, we add a full 50% to our landing distance, regardless of runway surface condition. Since we are only going in one direction when stopping (hopefully), and the control surfaces doing the steering (rudder and nosewheel) are not contributing to the braking in any way, directional control is not a factor.

Sure, airplanes and cars are different. But, IMHO, unless you are Michael Schumacher or Chuck Yeager, for 99% of the conditions anti-skid will do a better job for 99% of the drivers.

yes and no.

one, it depends on how well the abs system is designed.

two, it depends on surface. on gravel and snow it will lengthen stopping distance as when the wheel is locked, a "wall" will begin to form in front of the tire helping to slow the car. this wouldn't happen with abs. i had an on/off switch in my wrx and could match the abs with it off a couple times. but to do so consistently as the abs can would be highly difficult. there are some drivers that can better the abs. but in normal driving i wouldn't count on it. it will save your ass more then it will hinder you.

The Sales Manager did tell me that ABS was first developed for planes (which I did not know).

Originally posted by 73JPS
... we add a full 50% to our landing distance, regardless of runway surface condition. ... . But, IMHO, unless you are Michael Schumacher or Chuck Yeager, for 99% of the conditions anti-skid will do a better job for 99% of the drivers.

... Since I am NO Michael Schumacher or Chuck Yeager, I'm glad that it will help me stop in a shorter distance!

;)

Originally posted by jeremy
yes and no.

one, it depends on how well the abs system is designed.

two, it depends on surface. on gravel and snow it will lengthen stopping distance as when the wheel is locked, a "wall" will begin to form in front of the tire helping to slow the car. this wouldn't happen with abs. i had an on/off switch in my wrx and could match the abs with it off a couple times. but to do so consistently as the abs can would be highly difficult. there are some drivers that can better the abs. but in normal driving i wouldn't count on it. it will save your ass more then it will hinder you.

...Thanks, ... :confused: But are you saying that if I'm on dry pavement with (Mazda) ABS on - it might take longer?

Typically in car racing, shorter distance are possible without ABS. In F1 for example, they don't have it, although it may be due to regulations (safety could be a good arguement against that, and traction control is/was permitted for 2002).

I believe that the earlier ABS systems worked on the model that if one wheel locks up, ABS will take over all the wheels, even if they still have traction. I think more sophisticated multi-channel ABS systems now have independant sensor readings to prevent this from being such a disadvantage. Also, I think that ABS 'senses' (vehicle speed vs wheel speed) lockup before it actually occurs. Hence, the percentage of braking left between ultimate threshold braking and sensed lockup is also some wasted braking efficiency.

For we typical drivers, the best benefit of ABS, besides the fact it releases a locked wheel many more times quicker than a human, is that it eliminates a huge amount of processing power, and muscles coordination/skill when other variables have to also be taken into consideration. In AutoX and lapping with my previous FD, I always left the ABS engaged as it made my life easier to concentrate on placement and exit strategy of the vehicle coming into a turn. Sure, I gave up some time in braking, but I felt I could gain more concentrating on other things. Pro drivers have the skill to handle the extra load of variables and hence could include the benefit of non-ABS on a track. I'm curious if SCCA National champs chose to keep their ABS active.

Originally posted by FritzMan
Typically in car racing, shorter distance are possible without ABS. In F1 for example, they don't have it, although it may be due to regulations (safety could be a good arguement against that, and traction control is/was permitted for 2002)... It's all due to regulations. The only reason why traction control was allowed in 2001, is because it was too difficult to look through each team's proprietary ECU software to determine whether or not someone was using some form of traction control. So, in fairness to the other teams, they allowed it across the board.

They are now looking into eliminating alot of that again.

The only time ABS extends braking distances is if it's from a low-end street car that is racing. ABS systems for racing, and high-end sports cars, are not detrimental anymore.

---jps

The big thing with ABS isn't that it reduces stopping distances. It maintains steering control under low traction and/or threshold braking. When I need to slam on the brakes, I like having my steering continue to work without having to pump the brakes.

Originally posted by Rich
The big thing with ABS isn't that it reduces stopping distances. It maintains steering control under low traction and/or threshold braking. When I need to slam on the brakes, I like having my steering continue to work without having to pump the brakes.

Thanks ... I was wondering about the stoping distance, becaue I was #4 in a 6 car accident on the freeway during the morning commute a few weeks back ... I felt I was driving a safe distance before I saw the red brake lights ...

:(

I guess I didn't make my point clear. If you're asking about reducing stopping distances, ABS isn't the right place to look. Upgrade tires first, then possibly the brakes. Most places I've looked say that ABS doesn't reduce or increase stopping distances in the dry much. A 5 second goole search turned up these quotes and the links on the first page. I just picked the relevent quotes from the first few links that worked. I will let you judge whether or not the sources are honest:

http://www.auto123.com/en/info/columns/advice/view.spy?artid=599
"Because there is a high friction ratio between tire and road on rough and dry pavement, there won't be much of a difference in braking distance whether using ABS or not."

"Shorter braking distance and better steering control on slippery surface are the main advantages of antilock systems. ABS does not make much of a difference on dry pavement but do provide more stability when applying brakes in emergency situations."


http://www.mucda.mb.ca/aboutabs.htm
"Is the stopping distance shorter with ABS?
No! From early commercials, it may have looked like you could stop on a dime. That instantaneous stop is not realistic. When braking on dry or wet roads your stopping distance will be about the same as with conventional brakes.
You should allow for a longer stopping distance with ABS than for conventional brakes when driving on gravel, slush, and snow. This is because the rotating tire will stay on top of this low traction road surface covering, and effectively "float" on this boundary layer.
A non ABS braked vehicle can lock its tires and create a snow plow effect in front of the tires which helps slow the vehicle. These locked tires can often find more traction below this boundary layer."



http://cartalk.cars.com/Mail/Letters/05-16-97/9.html
"The Insurance Institute for Highway Safety has issued statements claiming antilock brakes do not provide a substantially shorter stopping distance on dry pavement, nor have they reduced the number of crashes in vehicle insurance claims.
General Motors has released statements saying that their antilock brakes will give shorter stopping distances with the exception of gravel roads, where stopping distances may be longer, but the driver will still benefit from increased steerability.

http://www.csu.edu.au/division/healsafe/webpages/guides/ABS.htm
"Always assume that ABS equipped cars will take the same distance to stop as cars which are not equipped with ABS. "


http://www.nhtsa.dot.gov/cars/problems/equipment/absbrakes.html
"Do cars with ABS stop more quickly than cars without? ABS is designed to help the driver maintain control of the vehicle during emergency braking situations, not make the car stop more quickly. ABS may shorten stopping distances on wet or slippery roads and many systems will shorten stopping distances on dry roads. On very soft surfaces, such as loose gravel or unpacked snow, an ABS system may actually lengthen stopping distances. In wet or slippery conditions, you should still make sure you drive carefully, always keep a safe distance behind the vehicle in front of you, and maintain a speed consistent with the road conditions."

Originally posted by Rich
... A 5 second goole search turned up these quotes and the links on the first page. I just picked the relevent quotes from the first few links that worked. I will let you judge whether or not the sources are honest ...

Thanks Rich, for all of the links and info!

:)

True, I never know if the stuff I read on the web can be trused or not ... I remember those old car comercials where it may have looked like you could stop on a dime ... so I'm glad that we have this forum around to learn from!

:D

You gave me a lot to think about!

Thanks for everyone's input on the subject, too!

Looks like the salesman was right.

thanks for backing me with some more concrete qoutes rich. i'm impatient and never make it to quoting.

http://www.whnet.com/4x4/abs.html

Good ABS pretty much always results in shorter or at least equal stopping distances compared to non-ABS, from what I understand. It isn't used in racing much because it isn't allowed. If it was allowed, I would expect every car in the series that allowed it to have ABS at the next race. Same thing with traction control, though street cars are pretty much always slower with TC on. Perhaps ABS is the same way -- you can make a high-end, race-oriented system that results in better performance, but cheap ones increase stopping distances when compared to a good driver (note: only a small percentage qualify as "good drivers"). However, I think ABS systems are more mature and the best performing system is also the safest system (unlike TC), so I would think that the ABS on all modern cars is good enough that it is better than just about any driver in most situations.

ABS is also nice for avoiding flat spots on your tires at the track.

-Max