AntiLock Braking-Is this how it feels?

1769 Views 21 Replies 14 Participants Last post by tasteycow, Jan 21, 2002

SlimChance

Discussion Starter · Jan 3, 2002

I purchased my 01RS last April and haven't regretted it since. Anyway, we're finally getting some snow here in Denver and I wanted to test out how the RS handles in the snow. And I'm concerned that my antilock braking system(still stock) is working properly.

When going down a snow pack street and and I slam on the brake, I here kind of a pulsing grinding sound and the brake pedal pushes back on my foot(very strongly). And the car doesn't seem to slow down at all. It seems that the braking improves that when the pedal pushes back, I really, really push down on the pedal.

Is this normal operation? I have taken the car to the track a couple of times and was wondering if I hadn't done some damage.

Thanks for the feedback,

Slim

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SubaruStu

· #2 · Jan 3, 2002

That's exactly what it is like! Crunchy-grindy-springy kinda
noise etc. It's not the smoothest ABS system I've ever
driven. Don't worry, that's the way it works.

Stu

JGard18

· #3 · Jan 3, 2002

yep, that's normal!

it's a little scarey, because you aren't stopping...but it's still slowing down more than if the tires were locked up and sliding

RS25.com

· #4 · Jan 3, 2002

That is exactly right - without that ABS you'd have slid off the side of the road already. Believe me.

Oh, and ABS and AWD don't do crap if you try to TURN while you're doing all this. Hence why I crashed my RS into a snow bank last year. Thank god for POWDER snow! :biggest:

BTW, I have found in my RS if I *do* start to skid, DON'T hit the brakes and DON'T floor it - keep the gas where it was - i.e., cruising speed - and drive like you're in a FWD car - it will go where the front wheels are pointing - mostly.

Good luck!

Hndatch627

· #5 · Jan 3, 2002

RS25.com said:
Oh, and ABS and AWD don't do crap if you try to TURN while you're doing all this. Hence why I crashed my RS into a snow bank last year. Thank god for POWDER snow! :biggest:

now was that you biffing the snow bank in the cars gone wild video?? hehe we're trying to figure out who it was.

oh yeah ur brakes are fine the reason the brakes felt better when the pedal kicked back is cause it is relieve pressure to the point where the wheel starts to spin agian and then instantly stopping again...it does this till the car actually stops.

RS25.com

· #6 · Jan 3, 2002

Hndatch627 said:
now was that you biffing the snow bank in the cars gone wild video?? hehe we're trying to figure out who it was.

No, actually I did it up in Tahoe. No video. being a dork and fuckign around on the snow. I went across the middle of the road and off the other side. Poof! Then the snowplows came and pushed a foot of snow on me while I was standing there!!! I was PISSED! Finally some guy in a Ford Bronco pulled me out - THANK YOU MR. BRONCO! Stopped up traffic for the 2 minutes it took to pull me out sideways... :lol:

I had some pictures up on my site for a while but since I *was* going to sell the car, I took them down. I guess I can put them up again now that I am keeping it, huh?

G

· #7 · Jan 3, 2002

Um, actually the ABS will help you turn more than non-abs would.

And for that matter, stopping distance in compact snow is better without the abs than with, if you can dig down into the snow and pile it up in ftonr of the tires. On ice, you're focked. Only thing that really helps on ice are chains or studded snow tires.

ChaosThom

· #8 · Jan 3, 2002

We had 8" of snow today. The first thing I did was test the ABS. It does seem like gravel under the pedal, but like they said, that's how it's supposed to work.

I pushed the pedal all the way and then turned the wheel. Response was a little delayed, but the car still turned well with the brakes full on. Try that without ABS and you'll do nothing but slide.

Of course, if you're going too fast, you're going to pay.

G

· #9 · Jan 4, 2002

ChaosThom said:
Of course, if you're going too fast, you're going to pay.

And that's EXACTLY why so many Subaru drivers end up in the ditch, in a pole, against a curb, etc. They think AWD and ABS will save their bacon when they go messing around doing stupid stuff. They just help make things better, they can't save you from yourself.

SlimChance

Discussion Starter · #10 · Jan 4, 2002

Thanks guys,

Slim

FuJi K

· #11 · Jan 5, 2002

as far as i know,

ABS will not have a shorter distance in braking in snow/gravel but will have a straighter braking line.
ABS will have shorter distance on pavement and will have a straighter braking line.

Non-ABS will have a shorter braking distance in snow/gravel but will not have a straight braking line
Non-ABS will not always have a shorter braking distance on dry pavement and won't have a very straight braking line.

Can someone explain if ABS will have a shorter distance in wet pavement?

FuJi

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yamarocket630

· #12 · Jan 5, 2002

FuJi K said:
Can someone explain if ABS will have a shorter distance in wet pavement?

FuJi

Yes, it will. Thre only reason ABS loses out in the snow or gravel is the "snow-dam" effect of snow or gravel building up in front of sliding tires. Since this isn't possible with water, and a rolling tire will have more grip than a sliding one, you will stop shorter.

Andrew

· #13 · Jan 5, 2002

i have a question about ABS and racing. why would you not want it on for a race?

FuJi K

· #14 · Jan 6, 2002

Andrew said:
i have a question about ABS and racing. why would you not want it on for a race?

sometimes one wants to lock the tires so they can drift.

i other situations, i.e. 22B, WRX STi and the WRXes that are equipped with adjustible centre locking diff., are not equipped with ABS. it's worthless because the centre will not let the other(front) spin faster than the rear. So ABS will do nothing much in this situation.

EXAMPLE: if you have centre locking diff. 50:50, would you need ABS? One of the front will spin the same speed as one of the rears. If you brake hard and lock up one of the rears, one of the fronts will lock up also.

ABS is to keep wheels from locking up. it's scensing all the wheels when braking. when one wheel locks up, the ABS will kick in and let that rotor go.

without ABS, i think one can trail brake better because the rears will be able to lock and lose traction for the trail braking drift. With ABS, i think it may be harder to get the rear to break loose for trail braking.

if anything is not right, feel free to correct me!

FuJi

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meebs

· #15 · Jan 6, 2002

stopping

if you are in desparate need to lose speed, in a straight line; non ABS is the way to go. Friction is your friend when you want to stop.

if you want to lose speed in a hurry, but also need to steer, ABS is the way to go.

ABS is for an "emergency" situation, and should not be considered a performace feature.

When racing you want max G-load on the tires when braking, without them locking.

G

· #16 · Jan 6, 2002

if you have centre locking diff. 50:50, would you need ABS? One of the front will spin the same speed as one of the rears. If you brake hard and lock up one of the rears, one of the fronts will lock up also

Um.

With open front and rear differentials, and a locked center diff, locking one tire would have no effect on the others. Lock a rear, and the torque will transfer across that axle to the other rear tire. Same at the front.

With a lsd/locked rear, open front, and locked center, a locked rear tire will severly retard the other rear tire (or lock it entirely), causing the entire rear axle to basically stop spinning, and the front axle will want to match speeds. If the front driveshaft (or input shaft, whatever's going on up there... I'm more of a 4x4 guy) has 0 RPM input, the tires are not going to want to spin together. I THINK on an open differential that if you spin one tire (like on a lift, just turning the tire by hand) the other will spin the opposite direction. You might be able to get one tire spinning backwards and one forwards, depending on what sick move you're doing.

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remarcable

· #17 · Jan 7, 2002

Some cars have scary ABS side effects, like the Ford Taurus. The damn brake pedal will actually try and rise all the way up!

ABS is great because it allows you to maintain lane control while panic braking. This is the #1 application of it and the reason it was invented.

G

· #18 · Jan 7, 2002

Yeah. I was watching a polce chase video on TV the other day and a cop laid on the brakes to avoid plowing into somebody and this HUGE cloud of smoke erupted from underneath.

No ABS for the coppers, they get school instead.

Xian

· #19 · Jan 7, 2002

from what i have read ABS is only for not having your brakes lock up on you not for shorter stopping distance. a non abs car should stop shorter in almost all conditions....

ivbdn

· #20 · Jan 16, 2002 (Edited)

My friend recently got a speeding ticket and is doing a home version of traffic school.

Anyway, in the little handout that was provided, it talked about ABS. When it pulsates, they suggest you step harder to ensure that it engages completely to all 4 wheels.

Then it goes on talking about stopping distances and what not. ABS was meant for emergencies only and will help you stop your car faster as opposed to a car that isn't equipped with ABS.

Of course it also mentions that proper tire pressure and other variables can affect the car's ability to stop. Tire specialists say that when a tire achieves 15% - 20% skid, the tire is working at its optimum level for braking situations. So if you've got a driver that can sense that, he/she would probably stop sooner than a car w/ ABS, but what do I know...I'm just a fan of the Impreza

!

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