ABS defeat?

[caramall2]

Hmm, interesting. I've wondered about the ABS sensitivity as well on glare ice. Certainly on panic stops in somewhat slippery conditions, ABS helps keep directional stability (depending on how bad one panics), but on the real icy stuff, it does seem to over pulsate (I don't like the feel either).

 

I've had a couple of low speed glare ice stops that seem to take forever. I'll have to try this.

[Guest]

Today after driving on some first serious slush/snow mix, I am definitely annoyed by the oversensitive ABS.

 

How is the switch working for you, LBGT?

[mccorry]

:subscribe:

[LittleBlueGT]

Today after driving on some first serious slush/snow mix, I am definitely annoyed by the oversensitive ABS.

 

How is the switch working for you, LBGT?

 

Works great!

 

I use it about 15% of the time in the winter.

[gianspi]

I've had a couple of low speed glare ice stops that seem to take forever. I'll have to try this.

 

I just tried it without the ABS on an icy road. WOW! The car stops much much quicker when I just pump the brakes manually!

[mwiener2]

I thought my new brembos would be too much braking for snow....but they're actually alot better. ABS doesn't get in the way. Since I can actaully feel what's going on at the wheel through the Brembos and the SS lines, I can actually feel the threshold of the ABS and stay off it. It's only untill the last 2-3mph that the ABS gets hard to control

[Xenonk]

just have to be more sensitive to threshold braking... I left my ABS on and I decided to use more of my e-brake turning on the icier corners.. it's no big deal if you clutch in prior to the e-brake pull.. I dont recommend this to anyone if they don't know what they are doing, it's something that has to be practiced with an instructor or that you have a large wallet to use to repair if something breaks.

[mbcracken]

Warning thread creep...

 

I was wondering, but have not investigate, how the pulling the e-brake would affect the AWD.

 

My buddies and I use to have a lot of fun working the e-brake with our POS highschool cars.

 

My fav e-brake snow story is when a couple kids threw a snowball at me in my old GLI. I was doing about 35, slowed a little grabbed the e-brake to do a 180 and executed perfectly. Scared the $hit out of the little brats to have me turn around so quickly that they took off running.

 

Cheers,

Mike

[bugblatterbeast]

Warning thread creep...

 

I was wondering, but have not investigate, how the pulling the e-brake would affect the AWD.

 

Cheers,

Mike

 

This might work but someone would have to try. On my old Acura, I'd sometimes disable the ABS by pulling the ebrake up one notch and wait 30 seconds. The ABS computer would flag the fault and shut down. The catch is I added some slack to the ebrake adjuster so pulling it one notch would push the switch but not actually pull the cable. If it wasn't so bloody cold outside I'd consider fiddling with the Subaru. Maybe someone with a warm garage can try

[bergs]

So with this mod....how does it affect the cruise control?

 

My RS lost the cruise if the ABS fuse was pulled....will it happen with this too?

[gianspi]

^ My cruise light was blinking. But after a couple restarts it is not on anymore. Only the ABS and "brake" light is on.

[Xenonk]

generally speaking, pulling the e-brake is bad if the car is still in gear.. if you pull the ebrake and push in the clutch, it's ok, the front end is an open diff, so it'll just spin whatever left from the front (so long the tires are still spinning at the same direction prior to clutching in), normally you want to incorporate braking, clutching, and pulling the e-brake to make a quick tight turn on LOOSE pavement (such as gravel, snow, ice, or other slippery stuff) in a specific order as well. Unlike a fully built rally car with a hydraulic electronic tranny that disengages the center diff when you activate the e-brake, our production cars are not that sophisicated.

 

Sure you can just yank the e-brake alone, but dont come crying when you need to repair the center diff and tranny.

 

The technique is designed so that when you do hit the brakes, you achieve full-lock up, but you modulate the roll of the front wheels to give you just enough control to make it your pivot point.. you achieve this with clutching in the car (to prevent tranny damages from any back lashes or negative forces on the tranny) and modulate the brakes just enough to make the front end bite so that the rear end will slide out.

 

takes practice, lots of slippery stuff, and of course, slow speeds and a safe place to practice in.

[mccorry]

I don't see how one of the front wheels can turn with the rear wheels locked without causing some binding in the center diff...

 

+1

[Xenonk]

I don't see how one of the front wheels can turn with the rear wheels locked without causing some binding in the center diff...

 

the key is clutching in to disengage the power off. The front end is open, so any left over forces will dimenish from the open diff. You are locking up the rear so there's nowhere else for that force to go but to goto the front of the car to the wheel with the least amount of resistance (aka open diff).

 

When the center diff reaches max torque split to the rear, it sends the power to the front (by viscous coupling, think of it as an egg yoke inside an egg, spin the egg, stop it, the yoke is still sloshing around, friction from the egg yoke and shell will want to move the egg shell and continue to spin it, that's the best way described by http://www.howstuffworks.com).. so by pulling the ebrake, you are causing the front to reach full capacity at 50% torque transfer since now the rear is static... remember, the center is still viscous.. not mechanical.. you're still just spinning fluid.. you're probably thinking that it's mechanical that if you lock the rears up, the diff clutches stop spinning (that's lockup on a mechanical like the EVO).. the fluid still spins and gets heated up from all the friction, but dont forget that the tranny is still spinning too which if the clutch isnt pushed in, the motor is still spinning the tranny.

[robinlsb]

the key is clutching in to disengage the power off. The front end is open, so any left over forces will dimenish from the open diff. You are locking up the rear so there's nowhere else for that force to go but to goto the front of the car to the wheel with the least amount of resistance (aka open diff).

 

When the center diff reaches max torque split to the rear, it sends the power to the front (by viscous coupling, think of it as an egg yoke inside an egg, spin the egg, stop it, the yoke is still sloshing around, friction from the egg yoke and shell will want to move the egg shell and continue to spin it, that's the best way described by www.howstuffworks.com).. so by pulling the ebrake, you are causing the front to reach full capacity at 50% torque transfer since now the rear is static... remember, the center is still viscous.. not mechanical.. you're still just spinning fluid.. you're probably thinking that it's mechanical that if you lock the rears up, the diff clutches stop spinning (that's lockup on a mechanical like the EVO).. the fluid still spins and gets heated up from all the friction, but dont forget that the tranny is still spinning too which if the clutch isnt pushed in, the motor is still spinning the tranny.

 

 

Golly Kieth, you are getting really smart!!! Seat time makes the difference!

[LittleBlueGT]

the key is clutching in to disengage the power off. The front end is open, so any left over forces will dimenish from the open diff. You are locking up the rear so there's nowhere else for that force to go but to goto the front of the car to the wheel with the least amount of resistance (aka open diff).

 

When the center diff reaches max torque split to the rear, it sends the power to the front (by viscous coupling, think of it as an egg yoke inside an egg, spin the egg, stop it, the yoke is still sloshing around, friction from the egg yoke and shell will want to move the egg shell and continue to spin it, that's the best way described by www.howstuffworks.com).. so by pulling the ebrake, you are causing the front to reach full capacity at 50% torque transfer since now the rear is static... remember, the center is still viscous.. not mechanical.. you're still just spinning fluid.. you're probably thinking that it's mechanical that if you lock the rears up, the diff clutches stop spinning (that's lockup on a mechanical like the EVO).. the fluid still spins and gets heated up from all the friction, but dont forget that the tranny is still spinning too which if the clutch isnt pushed in, the motor is still spinning the tranny.

 

I understand what you have said, have understood that for a while, but you did a nice job of explaining it.

[Xenonk]

Golly Keefe, you are getting really smart!!! Seat time makes the difference!

 

doh, you actually pulled out the sarcasm card, didn't you..

[robinlsb]

doh, you actually pulled out the sarcasm card, didn't you..

 

ABSOLUTELY NOT NOT NOT. It was a heartfelt compliment. I don't know why you took it as sarcasm. It certainly was not meant to be that. I gotta a LOT of respect for you kid, and THAT IS NO LIE!

 

 

You show to a lot of people the commitment required to really do well in the racing game. And I suspect that, we will here more about you in the future, IN THE NEWS!

 

So I am sorry if you took it the wrong way.

[Xenonk]

^ ah ok, there's so many others that pull that sarcasm card on me all the time, I wasnt sure if that was the case.

 

 

Does anyone know if the GT is just relying on the speed sensors on the hubs to activiate the ABS? That would probably answer the question of why it's soo sensitive. I believe more higher end cars use accelerometers and as well as electronic brake sensors for the pedal and as well as pre-emptive brake/caliper positioning for wet conditions for the ABS to function "better" than relying on the speed sensors from all 4 corners.

[Impulse]

wait, so how did you do the defeat switch? ive been reading this thread over and over and still cannot find the pictures/walk through/description of how you wired the defeat switch?

[KartRacerBoy]

Keefe, I've been having fun at about 10-20 mph with my handbrake to rotate the car into opposite lock (20-30 degrees) but with power to the front wheels while on the handbrake. I meant to pull the car around with power while on handbrake. I figured it would shorten the e-brake life (bye-bye pads) but not too much in 15 degree weather since it would hard to overheat it. But you're saying it's bad for diffs becz overheats the center diffs and rear diffs fluids (being viscous not mech diffs)?

 

If so, replacing fluids in diffs is probably a key to longevity (generally and abusing e-brake specifically), n'est pas?

[Xenonk]

actually, it's your brake shoes in your rear drums that may take a beating, but if done correctly, it's not your pads that is wearing out, it's your ebrake cable that is being over-stretched.. the GOOD thing is that in the snow, there's less friction.. not to mention that our cars are open diff up front, so if there's a lot of friction from the rear, it will send power to the front tires and it will spin the tire with the least amount of grip.

 

Most likely it will heat up the center diff more so than anything.. since you have a spinning tranny (input) and a spinning front shaft (output) but a stationary rear (the other output).. so with that difference from one input and two outputs, that would give the fluids something to rub on since the difference gets larger and larger if you use higher/taller gears.

 

replacing the fluids is a good and happy life for the viscous diffs.. if these were mechanical diffs, we would all be in trouble when pulling the ebrake in such fashion. You would need constant rebuilds on the clutch packs.

[KartRacerBoy]

Should've said shoes. Yes, lots of snow. I try not to play rally racer when cars are on street or near turns with brick mailboxes at streetside!

[LittleBlueGT]

wait, so how did you do the defeat switch? ive been reading this thread over and over and still cannot find the pictures/walk through/description of how you wired the defeat switch?

 

I thought I wrote it up.

 

I used a relay to mimic a blown fuse, can't rmember which (can't find out now either because my car is in the shop) fuse but it is not that hard. I have done it on every car I have owned.

 

I cut no wires, just pulled a fuse, relocated it and used a relay to make the ABS computer think the fuse is gone.

 

I press the switch and then the ABS light comes on and will not work again until the switch is turned off and the egnition key is recycled.

 

The nice thing about not cutting any wires is if I ever need warranty work it is 100% reversible.

[robinlsb]

^ ah ok, there's so many others that pull that sarcasm card on me all the time, I wasnt sure if that was the case.

 

 

Does anyone know if the GT is just relying on the speed sensors on the hubs to activiate the ABS? That would probably answer the question of why it's soo sensitive. I believe more higher end cars use accelerometers and as well as electronic brake sensors for the pedal and as well as pre-emptive brake/caliper positioning for wet conditions for the ABS to function "better" than relying on the speed sensors from all 4 corners.

 

The LGT has a four channel system w/g-sensor. Speed sensors on each wheel.