ABS brakes - good/bad?

[WALKA]

not to mention it saves your track tires from flat spots

[Gairloch]

Unless you get them from going sideways

[kbrew8991]

its hard to go off perfectly sideways and stay that way... esp with our low polar moment of intertia

not that I've had alot of experience at spinning off and/or going off or anything...

[kevinp]

I have to disagree with the sentiment that a human can't "out-brake" ABS. I attended a driving course for the military. The "highest performance" car they had there was the Police Interceptor Crown Victoria. They pulled the ABS fuse because 1) having ABS makes it impossible to stop using a threshold braking technique and 2) when driving at 10/10, ABS hurts more than helps. Someone also said that ABS was so that you could turn while braking. WRONG. ABS is so that when Average Driver jams the brake pedal to the ground, the back tires won't lock and send the rear of the car to where the front is supposed to be. Early in the process of teaching my 15-year old daughter how to drive the deuce (which is not equipped with ABS) , I demonstrated jamming on the pedal and executing threshold braking. While she enjoyed the spin that resulted from just squishing the pedal, she saw the value in threshold braking.

For everyone who says that ABS is "better" in DRY, relatively well maintained roads, I say that you need to learn how to use your brakes.

<wait while I put on the fire-proof uniform>

Alright, bring it.

[kbrew8991]

OMFG how many damn times do I have to say "it depends on the car/system"

Ford - sucky abs
MR2s - good abs

/thread

[Gairloch]

Like Ken says, and I think I mentioned at some point, not all ABS systems are created equally.

Originally Posted by kevinp

Someone also said that ABS was so that you could turn while braking. WRONG. ABS is so that when Average Driver jams the brake pedal to the ground, the back tires won't lock and send the rear of the car to where the front is supposed to be.

Kevin, I'm sure they mentioned the effects of going outside the traction threshold in that driving course you mentioned. I'm sure they also mentioned that while a tire is skidding it is incapable of providing any directional influence because there is not enough grip to influence vector. A good example of this would be what happens when you toss a small fuzzy animal across a freshly waxed floor You watch them scramble to move their own direction but their momentum keeps them going in a straight line because they have no grip.

There are two purposes behind ABS. First is because a machine that can monitor whether a tire is turning or skidding is going to be able to ride the traction threshold much closer than a person can, there's just no two ways around that. All we have to work with is our butt dyno, ABS can actually monitor whether the tire is turning or not and adjust accordingly. Older ABS systems were not precise enough in this process to exceed the capability of a skilled driver but that hasn't been true for years now. The grip of a tire that exceeds the traction threshold gives you much less grip than a tire that is still inside that threshold.

The second reason for ABS is indeed to maintain the driver's ability to steer a car during a hard stop. If a tire is skidding it's like that fuzzy creature skimming across the waxed floor and it doesn't matter what you do with the steering wheel.



As is demonstrated in the preceeding graphic not only does braking require a measure of a tires finite available grip but so does turning. This means that if you want the tire to not only slow down the car but also provide direction you're going to only have a percentage of the total grip available to each task. Managing how much grip each task is consuming is very difficult for even good drivers; that is why good driving instructors will advise especially their newer students to avoid trail braking (braking while turning). The second benefit of ABS is that if a driver is required to manuever while braking there is very minimal chance of locking up the tires, skidding, and taking away both the ability to stop and to steer.

[kevinp]

Originally Posted by kbrew8991

OMFG

snip

I have hemmed up many a soldier for that. Totally uncalled for....

I would say that ANY ABS system is inferior to an experienced driver. "Butt Dyno" has nothing to do with knowing that point at which the rear tires lock. The ability to modulate the brakes AT THAT POINT is not limited to a computer or mechanisms. Pick ANY vehicle (ANY) and I still believe that an experienced driver can stop it in less distance without the ABS. I have seen it, experienced it inside the car and done it behind the wheel.

Kevin

[kbrew8991]

well, this doesn't look like an Army base to me no offense, but this thread is getting beat to death because there is no hard and fast rule that ABS is never better, or ABS is always better.

the MR2 system rides this magic line, its just modern enough to be good (many channels, very quick pulses), but not so modern it "overthinks" stuff and ends up being worse because of it (Mercedes and BMW comes to mind)

You're welcome to attempt to pull a higher decel than 1.26g out of a stock suspension MR2 @ 2700lbs (or more if you want) with driver to prove me wrong though. But you won't. And even if you do, I can do it every single lap every single time...

Your experiences sound like they're in big fat luxobarges, HumVees, etc. Not that there is anything wrong with that, but they aren't exactly track weapons

[kevinp]

Originally Posted by kbrew8991

well, this doesn't look like an Army base to me...

No, you're right. It's a place where people should actually be a little MORE cautious and considerate. Or maybe that's just my opinion, too.

Originally Posted by kbrew8991

but they aren't exactly track weapons

THAT depends on the track.

I'm going to drop it. I agree that it's one of those things that would be hard to prove or disprove. My personal preference is no ABS. Yours is for ABS. Tomato, tomahto, speaking phonetically.

Kevin

[kbrew8991]

I've done what I can to experiment with both with the MR2, and its pretty stark how different it turns out

the OP asked about MR2s, and we crapped on this thread into a war on if it was good/bad period without regards to the application....

[sleepermr2]

Originally Posted by kevinp

Someone also said that ABS was so that you could turn while braking. WRONG. ABS is so that when Average Driver jams the brake pedal to the ground, the back tires won't lock and send the rear of the car to where the front is supposed to be.

Gairloch nailed it. as i said earlier, ABS IS designed so you can turn while braking. i dont have a whole lot of experience with racing but im a tech and i know for certain what ABS is intended to do.

[kbrew8991]

more modern ABS systems, specifically those integrated with stability management, won't allow alot of rotation while the ABS is activated

see also: old ABS and very modern ABS systems *can* suck and make you slower there is the right amount of intervention where all it does is pulse the brakes right at the limits of adhesion only

[midngn]

Any one have issues when you are under somewhat heavy braking and you hit some bumps in the road, it whacks out the system and the car won't stop? My car has a very stiff set up, but it seems like hitting bumps in the road messes with the ABS. If I quickly release the brake and depress it again, it "resets" but it can be scary. Anyone experience this?

[kbrew8991]

haven't been running anything that could be construed as stiff yet, but I seem to get better decel force the more rapid I can get the ABS to pulse

ymmv

[midngn]

Thanks Ken, not sure if you realize who this is, but it is Jeff from Hankook Tire. As of today I will be leaving as the Motorsports Manager and taking a job with Pirelli Tire.

[TreyMR2]

as far as my MR2 goes, I very rarely have issue's from not having ABS but there are a few times you'll wish you had it. Mainly in the rain. I almost never lock them up in the dry but its like super easy in the rain. If I had to make a call on this I'd have to vote ABS over non ABS. I've had times in my moms 2008 accord where I had to slam on the brakes in the rain on the interstate and you can still steer that car like its on rails, when trying that in my MR2 would have ended in my rear ending someone.

[kbrew8991]

Originally Posted by midngn

Thanks Ken, not sure if you realize who this is, but it is Jeff from Hankook Tire. As of today I will be leaving as the Motorsports Manager and taking a job with Pirelli Tire.

ah yeah, got your email