Weird ABS Feedback After Install

[Kampfzentrum]

I have a '05 RS wagon and recently swapped out the front suspension to a sedan (sedan sways, extended axles, etc.) to get proper suspension geometry for my D-specs and Kings.

Today when driving home from work, the ABS brakes started going off just before coming to a complete stop - only on the front passenger side. I did a visual and the rotors are fine, axle nut is still in the last torqued position. I didn't take off the wheel to look as I got home tonight at 11pm and am going back tomorrow at 7am to do a 12 hour day - what do you think pays for my hobbies?

I am worried that something is coming out of place due to the recent suspension swap. What would cause this?

I pulled the ABS fuse and it stopped, but I know the condition is still present. After the fuse was pulled I got a "brake" and "ABS" light.

Anyone?

[UP2MTNS]

keep the fuse out, ignore the 'brake' and 'abs' lights.

[williaty]

You probably pissed off a wheel speed sensor.

[97ScoobyL]

Make sure all of your wheel speed sensors are in tight and have no rust build up on the mounting surfaces. Also make sure they are plugged in. :shootsself:

[Newk_Rally]

i've had my abs pulled for a year and wouldn't think about putting it back in

[Kampfzentrum]

i've had my abs pulled for a year and wouldn't think about putting it back in

Yeah, you also live in CA. Try that up here and you'll be changing your mind.

[UP2MTNS]

Yeah, you also live in CA. Try that up here and you'll be changing your mind.

Try driving a car with a better ABS system, and you'd change yours ;) I don't know what it is about Subaru ABS, but it sucks.

I drove my WRX in all conditions, and now I fully race it, and I'd never put it back in. Unless the 'RS' ABS is significantly different from the WRX version?

Mine would kick in at the worst possible time, for no apparent reason (like downhill corners on DRY pavement) and was even worse in the snow.

Besides, ABS was designed for idiots that can't drive.

[Kampfzentrum]

Besides, ABS was designed for idiots that can't drive.

Well, I guess I'm a f*ckin' idiot then, cause when I'm doing 40 downhill on an inch of ice - it's pretty nice.

[UP2MTNS]

Well, I guess I'm a f*ckin' idiot then, cause when I'm doing 40 downhill on an inch of ice - it's pretty nice.

I bet w/o it you'd still do fine going 40mph on ice...

ABS its designed for the average driver, who, in an emergency situation will just slam on the brakes, lock them up, and then slam into whatever is in front of them because once the brakes lock up, you lose steering (duh).

ABS makes sure those people can still steer despite slamming on the brakes.


Like I said, if its working properly....then good for you. I found my ABS to work like crap, and its not uncommon.

http://nz.answers.yahoo.com/question/index?qid=20071202122209AAvt5EG

[williaty]

On pure ice, the ABS likely has an advantage due to the fact that the mu is so low that threshold braking is beyond the capabilities of the human foot. With all 4 wheels on a surface like dry snow or gravel, ABS is a disadvantage because PURELY FOR STOPPING locked wheels work better. On dry tarmac, it's a bit of a tossup. Often, a good driver can out-brake the ABS by threshold braking. However, the ABS has the ability to "unlock" a single wheel at a time as it skips over a bump (if the ABS system isn't retarded like Subaru's is).

However, if you don't have all 4 wheels on the same surface, ABS is untouchable for the simple fact that it can apply less torque to the wheel that's on grass than the wheels that are on tarmac.

[DN1911]

mine started doing the same thing after a wheel bearing install. found the sensor not in the optimal position for a strong signal. the ABS wires have since all been cut :) like it better with out it. and just get some snow tires for winter, they are way more benifical in winter than ABS :) the only downside i see to no ABS is no cruise control....

[Kampfzentrum]

On pure ice, the ABS likely has an advantage due to the fact that the mu is so low that threshold braking is beyond the capabilities of the human foot.

I could not have said it better myself. I've driven in icy conditions and have had the ABS go out. The brake pedal is so sensitive (i.e. what Ty referred to as the "threshold") that you either are driving or slipping. There was no fine tuning with the pedal like when on dirt or tarmac. Period.

[williaty]

It should also be said that it depends on tires and conditions. The better your tires are matched to the conditions, the more likely you are to be able to out-brake an ABS system. Keep in mind that ABS is not supposed to make you stop shorter, it's designed to keep the wheels rolling at all times so you maintain directional control of the vehicle. The potential for longer stopping distances was a design compromise for the retention of directional control.


And Kamp, "threshold braking" is a specific braking technique.

[Kampfzentrum]

And Kamp, "threshold braking" is a specific braking technique.

Well it sure sounded right.

[UP2MTNS]

The brake pedal is so sensitive (i.e. what Ty referred to as the "threshold") that you either are driving or slipping. There was no fine tuning with the pedal like when on dirt or tarmac. Period.

in that situation, down shift and let your differentials do the work....its a built in ABS system that slows you down AND keeps the tires rolling so you can still steer. At the same time it increases the threshold/decreases brake pedal sensitivity (ie its harder to lock them up) because now they're braking against the engine as well and you have a LOT more control.


same concept going uphill even though it seems counter intuitive....in a higher gear, its easy to get on the gas (to keep your speed up) but then once you lose traction there's no load on the engine and all 4 tires break loose because you suddenly jump from 3.5K to 6Krpms and you're sliding off the road....by keeping your rpms up, you're less likely to 'spike' the rpms and suddenly lose traction. If you do, its much more controlled and you have a lot more throttle control to regain traction from the slide (or just keep modulating the throttle to hold your slide and have fun with it :) )

[williaty]

That only works on cars with good differentials.

Those of us with an RS have an open front, and open rear, and a center so weak it may as well be open.