Sometimes ABS sucks

[CNY_Dave]

Does anyone have a quick hack for turning the ABS on and off?

 

I suspected there were situations where it was bad, and indeed found one last night.

 

 

Dave

[nipper]

install a on off sitch at the ABS fuse (dont foregt you still need that fuse in line).

 

nipper

[tomson1355]

Hey Dave, not a good couple of days in central NY. I had to plow and sand twice this am to get the milk truck up the driveway.

 

Anyway, I damaged the LF ABS wheel sensor replacing a CV boot on my daughter's 97 Legacy GT. The ABS light is on and the ABS does not appear to work. I'm not recommending this as a method to turn off your ABS, but that seems to be the effect.

[OB99W]

Does anyone have a quick hack for turning the ABS on and off?

 

I suspected there were situations where it was bad, and indeed found one last night.

I hope what happened didn't involve someone getting hurt. However, I'm not sure that disabling the ABS is a good idea. Food for thought:

 

1) Very few drivers have the skills to do a better job of stopping a vehicle without ABS than with it, under certain road conditions. If you're one of those who can, congratulations. However...

 

2) How can you anticipate when having or not having ABS would be better? You might decide that you can do outperform the ABS under the conditions you're observing, but what if you then hit a spot where the ABS being active would be an improvement? Would you have the time and presence of mind to switch the system on?

 

3) What would happen if you had an accident under road conditions where the police and/or insurance company felt ABS would have prevented or minimized damage or injury, and it was found that there was a modification to switch off the system (whether or not you claimed the ABS was active at the time)?

[nipper]

Most people are under the false impression that abs will shorten thier stopping distnace. This is true on dry pavement, sort of maybe true in bad weather.

 

The one time abs is bad, is on a loose surface, such as gravel or unpacked snow. This is when you need a switch. If you hard wire a switch, i recomend a latching relay. This way when you shut off the car it resets.

 

What people seem to forget is the two simple rules in bad weather

 

SLOW DOWN

BRAKE SOONER and leave alot of distance between you and the car infront of you.

 

Also test the road surface before you have to stop. Especialy if you have trraction control. Traction control can give you a flase sense of the road surface. Most people use tires spinning at start up as a measure of how slick a snow/ice covered road is. With traction control you loose alot of feedback.

 

ABS can shorten your stopping in slick conditions as oppsed to not having abs, BUT it will not keep it as short as dry weather. It will also haelp you maintaine control.

 

If you almost had a bad expierience with ABS, imagine what it would have been like without it.

 

Practice with ABS in an empty lot at the first real snow to refresh yourself on what it feels like.

 

nipper

[CNY_Dave]

In my case, I was going down a steep hill covered with snow and some slightly more slushy stuff.

 

The ABS kept me from stopping on the hill (low speed).

 

How do I know?

 

1)In my non-abs truck, in conditions like that, locking the brakes was the optimal solution- the wheels lock, and dig through the crud, and you stop. Same hill, same test conditions. Of course your tires have to have a fairly aggressive tread for this to work.

 

2) to stop on that hill with the subie, I yanked the e-brake and stopped in very short order.

 

For slowing on the hill, ABS was better. For stopping on the hill, ABS was a recipe for collision.

 

ABS is great, but repeat after me: the car is not smarter than me, and the primary safety system in the vehicle is... me.

 

 

Dave

[nipper]

Ah this is the achillies heal of abs. You need to do down hill descents at slow speed in neutral. What happens is (automatic) in gear abs will keep pulsing the brakes, and the drivetrain keeps applying torque. The ABS gets confused and does not stop the car. Between momentum going down hill, the driveline, and the abs the car will never stop.

 

In a manual this is when the switch would come in handy.

 

nipper

[backwoodsboy]

 

ABS is great, but repeat after me: the car is not smarter than me, and the primary safety system in the vehicle is... me.

 

 

Dave

 

I had ABS in my BAJA. I hated it when stopping in the snow.

With the antilock, the snow tires never get a chance to "bite down" into the snow when stopping, and greatly increases your stop-distance.

 

It IS nice when someone is braking WHILE turning (#1 sin of winter driving)

 

Like Nipper says..... it helps most people maintain control.

[idosubaru]

thanks for posting this, i had horrible problems last year, i am so glad to read this thread. being new to antilock brakes i didn't realize they would install something so pathetic in a vehicle. they trade a marginal improvement in safety in some areas for an enormous danger in bad weather...when driving is most difficult?

 

1) Very few drivers have the skills to do a better job of stopping a vehicle without ABS than with it, under certain road conditions. If you're one of those who can, congratulations.

in this case ABS is a POS.

 

my 1997 impreza OBS ABS system totally pissed me off last year, completely worthless. note my location....west virginia, terrain is steep, we get snow. on steep hills with snow it was literally IMPOSSIBLE to stop with the ABS, my wife couldn't even drive her own car. i don't understand how more people are not in accidents because of it. i had to drive the car, put it in neutral and the emergency brake was the only way to actually stop the vehicle. without the e-brake the ABS would pulse and pulse and never stop the vehicle. it wasn't even ice or that bad, any time it was snowy. my XT6 would stop on a dime with plain old all season tires.

 

my XT6 is unbelievably better in the snow than the OBS...same transmission, no antilock brakes.

 

Achilles heel as nipper said is an understatement.

[Manarius]

Well, I was in a situation where ABS would have been helpful. Two years ago I slid into a guard rail because my brakes locked up on slush. If I had ABS, I believe I would have been able to at least have avoided the turn rather than cock the wheels and slide straight into the guardrail head on.

 

I like the ABS on my SVX, I wouldn't trade it in for standard.

[CNY_Dave]

Well, I was in a situation where ABS would have been helpful. Two years ago I slid into a guard rail because my brakes locked up on slush. If I had ABS, I believe I would have been able to at least have avoided the turn rather than cock the wheels and slide straight into the guardrail head on.

 

I like the ABS on my SVX, I wouldn't trade it in for standard.

 

Overall, I find ABS useful, and I'm glad I have it.

 

I consider it a tool in my arsenal to drive well, effectively, safely, and in conditions that would make most run for mommy.

 

I also consider it my job to find where it does not help (or actively works against me!) and find effective strategies for dealing with those situations.

 

I hear rumors your insurance company may not pay if you have a switch to disable ABS and then you have an accident?

 

If the ABS fuse is in the passenger compartment, maybe I should tie some dental floss to it so I can yank it if need be? Or have some devious mechanism to deliberately blow the fuse...

 

Dave

[idosubaru]

What happens is (automatic) in gear abs will keep pulsing the brakes

oh man that is so annoying. on grades with snow you literally can not stop, absolutely baffling - would a manual do the same...in neutral...in gear?

[backwoodsboy]

I just put a blown fuse in the holder, and wrapped a wire over each blade.

The other end of the wire was connected to a switch in the ashtray with the wires loosely threaded in. If I was to be in an accident, one quick pull on the wire would yank out the switch, wire, and blown fuse. ....and a spare (good) fuse left in the ashtray was there handy to slide right in.

[85T-REX]

Two years ago I slid into a guard rail because my brakes locked up on slush.

Are you sure it wasn't because you were 17?

 

I used to drive an F-150 through the High Desert of California for my job. (Sand covered back roads) I pulled the fuse for the ABS because every time I hit the brakes and cut the wheel to take a corner (you know, rally style) it would slide straight through the intersection. With no ABS it would corner like a rally truck should.

 

Other than that, I think ABS is a good idea.

[OB99W]

[...]

1) Very few drivers have the skills to do a better job of stopping a vehicle without ABS than with it, under certain road conditions. If you're one of those who can, congratulations.

in this case ABS is a POS.

Which is why I said "under certain road conditions".

 

 

my 1997 impreza OBS ABS system totally pissed me off last year, completely worthless. note my location....west virginia, terrain is steep, we get snow. on steep hills with snow it was literally IMPOSSIBLE to stop with the ABS, [...]

I live in a hilly/often-snowy section of central New York, so I'm hardly a stranger to the conditions you've described. I didn't say ABS is perfect; it has its good and bad moments, and I've experienced the bad myself at times. It's easy to condemn ABS for the bad, but I'll repeat what I said above concerning disabling it:

However...

 

2) How can you anticipate when having or not having ABS would be better? You might decide that you can do outperform the ABS under the conditions you're observing, but what if you then hit a spot where the ABS being active would be an improvement? Would you have the time and presence of mind to switch the system on?

 

3) What would happen if you had an accident under road conditions where the police and/or insurance company felt ABS would have prevented or minimized damage or injury, and it was found that there was a modification to switch off the system (whether or not you claimed the ABS was active at the time)?

[OB99W]

I just put a blown fuse in the holder, and wrapped a wire over each blade.

The other end of the wire was connected to a switch in the ashtray with the wires loosely threaded in.

That approach leaves the circuit with no fuse protecting it.

 

 

If I was to be in an accident, one quick pull on the wire would yank out the switch, wire, and blown fuse. ....and a spare (good) fuse left in the ashtray was there handy to slide right in.

Even assuming that after an accident you were uninjured and remembered to do this, perhaps that time should be spent checking whether your passengers or people in any other vehicles involved were okay.

[CNY_Dave]

Which is why I said "under certain road conditions".

 

 

I live in a hilly/often-snowy section of central New York, so I'm hardly a stranger to the conditions you've described. I didn't say ABS is perfect; it has it's good and bad moments, and I've experienced the bad myself at times. It's easy to condemn ABS for the bad, but I'll repeat what I said above concerning disabling it:

 

 

My test-hills are outside Groton- not as steep as what you have near you, but one or two good ones to get to know the car.

 

 

Dave

[idosubaru]

i'm not slamming ABS and i don't disagree with your points. i think it's great, but a huge over sight. more people should know about it, and Subaru should do something about it. i don't care how effective a vehicle is at avoiding accidents that i have a 0.002% chance of seeing in my lifetime if the thing is physically incapable of even coming to a complete stop in conditions my wife has to drive in weekly. physically incapable of stopping??? that's my hang up, what other options do we have?

[OB99W]

[...]I hear rumors your insurance company may not pay if you have a switch to disable ABS and then you have an accident?[...]

Let's put it this way -- most auto insurance companies seem convinced that ABS is beneficial, hence they apply a discount to the policy if the car has ABS. How do you think the company will react if they find (especially after an accident where they might otherwise have to pay out a large sum) that you've installed a way of defeating it?

[CNY_Dave]

Let's put it this way -- most auto insurance companies seem convinced that ABS is beneficial, hence they apply a discount to the policy if the car has ABS. How do you think the company will react if they find (especially after an accident where they might otherwise have to pay out a large sum) that you've installed a way of defeating it?

 

Yep.

 

For me a defeat mechanism would be something to activate only after finding myself in the situation where the ABS was causing a problem. But, if going slow enough for this to rear its ugly head, most situations would be covered by yanking the Ebrake, albeit that only slows the rears.

 

I wonder what the duty C solenoid does when you're in neutral? If its in the 50/50 state (not being pulsed, or pulsing only enough to eliminate bind) that would transfer braking force from the rear to the front.

 

Hmmmmm...

 

You know, I bet you could get an idea what the duty c solenoid is doing by slapping a good 'ol analog dwellmeter on it, since that (mechanical points) is also a system where the wire is at gnd most of the time, with brief pulses to +12V. Or maybe just a good RMS AC voltmeter.

 

Dave

[nipper]

In neutral in a manual tranny you dont have the "creep" problem automatics do.

 

In neutral there is no need for the duty C to do anything (think about it).There is no torque for it to transfer. besides unless your engine braking, the brakes are in control, overpowering the driveline. Now if you manually downshift to first, then you have a 50/50 split.

 

The only time there is a huge investigation in an accident as to how the car was equipped or modified is if there was a fatality or a pedestrian hit (or assumed to be fatality). Then the car is gone over with a fine tooth comb.

 

Now there are ways to do it properly so no one can tell a ABS cut off switch form a fog light switch.

 

nipper

[CNY_Dave]

In neutral in a manual tranny you dont have the "creep" problem automatics do.

 

In neutral there is no need for the duty C to do anything (think about it).There is no torque for it to transfer. besides unless your engine braking, the brakes are in control, overpowering the driveline. Now if you manually downshift to first, then you have a 50/50 split.

 

The only time there is a huge investigation in an accident as to how the car was equipped or modified is if there was a fatality or a pedestrian hit (or assumed to be fatality). Then the car is gone over with a fine tooth comb.

 

Now there are ways to do it properly so no one can tell a ABS cut off switch form a fog light switch.

 

nipper

 

 

But, with an auto, in neutral, will it still creep is the question.

 

On a steep enough hill, it might.

 

 

You know, if you could just get the ABS to shut off for a split second, and lock 'em up right then, the ABS could be re-enabled because if the wheels are locked up, it doesn't know you're moving.

 

 

BTW, I did try stab-braking in this situation, you might get the speed down a skosh less, but not by much.

 

 

Dave

[nipper]

But, with an auto, in neutral, will it still creep is the question.

 

On a steep enough hill, it might.

 

 

You know, if you could just get the ABS to shut off for a split second, and lock 'em up right then, the ABS could be re-enabled because if the wheels are locked up, it doesn't know you're moving.

 

 

BTW, I did try stab-braking in this situation, you might get the speed down a skosh less, but not by much.

 

 

Dave

 

i said it would "creep in a few posts earlier i said it was more of an automatic transmission issue.

 

Stab braking is no differnt then just holding your foot all the way donw on the barke pedal with ABS.

 

nipper

[CNY_Dave]

i said it would "creep in a few posts earlier i said it was more of an automatic transmission issue.

 

Stab braking is no differnt then just holding your foot all the way donw on the barke pedal with ABS.

 

nipper

 

Except for that 1st better 'dig in' that you get before the ABS can figure out something is up, and can get the solenoids, etc. activated. It doesn't get you much, but can have some interesting effects at speed.

 

 

Dave

[OB99W]

Somewhat interesting/related reading:

http://www.oramagazine.com/pastIssues/0411-issue/041102t-finesse.html

 

Don't skip the last two paragraphs.