Disable ABS

Hi Tom, All!

On Wed, 10 Aug 2005 10:24:24 -0400, Tom Reingold wrote:

True. Putting studded snows on m'ladys Forester made a huge difference. I use the Michelin Alpin Pilots on my rex. They just don't offer enough grip on ice (despite being offered as an "ice" tire; the Arctic Alpin is much better, and no longer available, naturally) to get the ABS to work properly. The real problem, tho, seems to be in the way the ABS control modulates the brake pressure. The Subaru unit seems to pulse the brakes a lot slower than the GM I was comparing it to; Subaru is a definite on-off-on-off sensation, while the Caddy is more of a HUMMMMMMM. The dirt road issue is, I think, an entirely different thing, and may be common to all ABS systems (never tried _this_ with the Caddy ;-). When braking hard into a bumpy corner (washboards), the tires experience less grip, (and hence some wheel lock-up) as they skip thru the bumps. The ABS responds by modulating the brake pressure, giving the sensation of drastically reduced braking. You'd probably never notice this driving at rational speeds, but when cornering at the limits of traction, the effect is extremely disconcerting, and may result in a quick trip into the ditch at the outside of the corner! Trust me; I have tried both ways looking for that edge, and the difference is dramatic. With the ABS off, the WRX will hammer an apex and rocket out of a turn with very little fuss; point it and put the pedal down. With the ABS on, it is difficult to "turn in" to the apex properly; you either have to begin braking way early, or aim for an apex way short of where you really want to be, and then wait until things settle before getting back on the gas, neither of which results in a fast line thru the turn.

ByeBye! S.

Steve Jernigan KG0MB Laboratory Manager Microelectronics Research University of Colorado (719) 262-3101

Reply to
S
Loading thread data ...

Reasons for disabling ABS:

  1. You can actually stop faster without it. ABS was designed to allow you to manuever your car while stomping on the pedal, not necessarily stop you faster, in some cases it does have the affect of stopping you faster, but in my WRX that is not the case.

  1. Being able to actually lock the brakes can be advantageous for certain auto-x or roadcourse type races.

  2. The ABS in the WRX is WAAAAAAAYYYYY Y too touchy and has been documented by many nasioc people to engage while going over bumps w/o the pedal depressed.

  1. Trusting ones own instincts over those of a machine, I prefer being in control.

  2. I've found that big brake kits tend to suffer when using ABS in conjunction with them as the ABS computer (for lack of better terminology) is programmed to apply "w" amount of pressure on a "x" sized rotor that weighs "y" more/less than stock w/ "z" number of pots on the caliper. Change either "x" "y" or "z" and the formula is messed up. Same theory would apply if he went with a larger/smaller or heavier/lighter wheel & tire combo.
Reply to
iksalama

You're saying the WRX ABS causes brakes to "apply", with no brake pedal depression??

First I've heard of that one!

Reply to
CompUser

Reply to
Edward Hayes

just today at Nasioc I saw a 'tbs'/recall (sorry, don't recall which now) for '02 WRX ABS brake issue. Seems Subaru and NHTSA agreed the ABS can be disconcertingly slow to engage and some type of sensitivity adjustment can be made. Seems somewhat opposite of the complaint here. I dunno.

Carl

Edward Hayes wrote:

Reply to
Carl 1 Lucky Texan

In article , JD wrote: (snip)

I like ABS, too - I find it helpful in the snow. I finally got around to looking in the WRX manual's ABS section, though, and it says,

"When driving on badly surfaced roads, gravel roads, icy roads, or over deep newly fallen snow, stopping distances may be longer for a vehicle with the ABS system than one without."

Clearly they have /some/ reason for writing that. Then again, my understanding was that ABS was usually better for giving you extra ability to steer when braking rather than for reducing the stopping distance.

-- Mark

Reply to
Mark Carroll

formatting link
the above has a lot more insight on what I meant by ABS engages, The brakes themselves don't engage when going over a bump, but the ABS system can engage giving you zero braking power for a full second after hitting a bump. I should have been more clear.

Reply to
iksalama

allow

rotor

caliper.

Same

  1. Not really the case, while sometimes it causes you to stop longer, it is not designed to, and it is not designed to "allow you to manuever" either, just allow you to remain in control.
  2. Yes, every now and then not having ABS is good, but really only in extreme cases, not day to day.
  3. w/o pedal depressed?!?! if that has ever happened its a flaw elsewhere, not a flaw with the ABS, if it goes off over a bump thats gotta be a big enough bump to depress the pedal by shock value alone, or cause the sensor to read as such.
  4. VERY VERY VERY few people have better reaction time than a computer, and the few that do can still be caught offguard. differing your driving style is needed for ABS vs Non-ABS, just like Auto vs Stick. Just gotta know how your car handles and adjust.
  5. not sure the effect of big brake kits; but it is safe to assume that anytime you alter the braking system it will preform differently; and if the computer is unable to learn big brakes then an adjustment should be made so the system know what to do.
Reply to
xmirage2kx

Ok, that's *completely* different from what was clearly said initially.

Oh, BTW...if you're braking and running over a surface that's rough/ripply enough to get wheel (s)intermittently "airborne" and out of contact with the road surface, yes, the ABS will tend to activate on the wheel(s) that are no longer in contact with the road surface, possibly still with ABS operating on them for a short period after they return to contact with the road.

ANY vehicle that has ABS, not just the WRX, will do that.

Reply to
CompUser

Is this the old one from a couple of years ago, or something new?

Reply to
CompUser

Because it's true. ;-)

That's basically it!

Reply to
CompUser

ABS service bulletin thread;

formatting link
Carl

CompUser wrote:

Reply to
Carl 1 Lucky Texan

Thanks Carl...it is new.

The fact that NHTSA investigated and dismissed any safety concern, and Subaru *still* took action to address it, impresses me favorably.

Reply to
CompUser

formatting link
>

My original post was "The ABS in the WRX is WAAAAAAAYYYYY Y too touchy and has been documented by many nasioc people to engage while going over bumps w/o the pedal depressed." I don't know if its *completely* different. I said it engages, not applies the brakes. Though I wasn't 100% clear the way I worded it and I apologize.

Yes, but the WRX ABS system will at times have the above scenario happen even when drivers are not on the brakes going into the bump but apply the brakes shortly thereafter and have no brakes for about 1 second....lots of bad things can happen in one second.

Reply to
iksalama

  1. Kinda splitting hairs on that one aren't you? Doesn't allow you to manuever but allows you to stay in control? Either way the idea behind ABS is the three "S's" STOMP on the brakes, STAY on the brakes STEER the car. " The IIHS report, issued December 10, 1996, notes that in single-vehicle accidents, cars with antilock brakes are as much as 44% more likely to produce fatalities than are cars without the antilock system. " Taken from this website
    formatting link
  2. Thank you for saying exactly what I said, the OP never (at least not from what I read) stated why he wanted to unhook his ABS, maybe it was for this type of event?
  3. See elsewhere in this thread, I explained it more clearly. The way I wrote it was not how I intended to say it. The ABS engages, not necessarily the brakes...the brakes may not engage for a full second after hitting a bump which can be dangerous.
  4. Again, not for everyone. I seem to recall a magazine listing this as the #1 mod they'd do on a WRX if they were going to race it however.
  5. Show me the software that can effectively make this change and I'm all over it. I don't think it exists, if it did, everyone that auto-x's would utilizing a computer to manipulate their abs system in a manner that they feel comfortable with. (Similar to how engine management is used to optimize the fuel/ignition/boost/etc... to extract extra power) Seriously, if someone came up with this type of software, I think you could make LOTS AND LOTS of money from racers.
Reply to
iksalama

Lol...check with Bosch, they did Subaru's ABS.

Reply to
CompUser

Yeah....like bosch is going to give out its (most likely) proprietary ABS software to the general public, seems like a lawsuit waiting to happen there (BTW, I did contact them, they won't give it out). I'm not saying the software for the ABS can't be reflashed back to OEM specs by a subaru dealer, but that won't help the big brake situation.

Reply to
iksalama

Already been done.

Reply to
CompUser

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.