ABS unnecessarily kicks in while turning sharp

[93silverbulletSH0]

Just seeing if this is normal... When turning sharply (quick rights) the ABS kicks in (or at least the pedal shudders pretty bad) about halfway through the turn if I am still on the brakes relatively hard (not hard enough to kick in ABS going straight). I went out and made a couple different panic stops to make sure it was the ABS kicking in. 60-0 pedal to the floor ABS barely kicked in (mostly at lower speed), and pedal barely shuddered. 30-0 more shudder but still not as bad as when turning. 20-0 on the dirt caused pedal to shudder violently, worse than when turning but closer than others. One time I was pulling into my driveway, there was someone behind me so I pulled all the way to the right so they could go by as I slowed and made a right into my driveway. I was still going about 10 mph and using medium braking force when my tires went up the sloped curve into the driveway it did it again. No ABS light has come on, but I have't checked the codes. Does anyone elses car do this? I wast able to dig anything up through the search. Sorry for the long write up, I like to provide as much relavant info as possible. Thanks.

 

[290]

This happened to my friends 4x4 ranger, according to his mechanic it ended up being a bad wheel bearing and the slop in the wheel was causing his abs to go off while making left turns. The abs uses a hall sensor and a sloted disc on the inside of the wheel to sense if the wheel is turning or not while braking. The sloted discs are plastic in the front and metal in the rear. Something could be up with the sensors, the discs, or posibly bad bearings.

 

[jedhead]

Check to make sure the abs rings on the hubs are not cracked.

Bob

 

[NJSHO]

Are you lifitng up a back tire by any chance when turning sharply? With my subframe connectors I sometimes lift a tire when going up a driveway with strange slope. You could be sending the abs system into ice mode if there is such a mode on these cars.

 

[93silverbulletSH0]

I don't think my wheel bearings are bad, steering is very tight, no clunks when turning. The front ABS rings do not appear to be bad, couldnt see the back ones from under the car (must have to take off the wheels?... have to go to work soon, so I will check another time.) I wish my car could lift a tire! It is bone stock for now. Strut tower bars and subframe connectors will probably be one of the first mods. I like a stiff car and would love to get rid of the rattles over bumps. I hate when you can feel how soggy a car is. I am driving like a grandma until I get the potential SHOboom diff problem fixed, 't and the original 125k mile clutch replaced (still engages well and doesn't seem to slip, but I hear it is the bearing I need to be weary of). Back on topic-attempted to check the codes and nothing came up. Are there only codes stored when the ABS light stays on? Is there no "everythings good" code?
Back off topic-NJSHO-Are any of the subframe connectors you can buy better than others? I have a friend that is very handy w/ tubing and a welder (builds prerunners) If I had him fab something up what are the best mounting points? Does it actually bolt to the front subframe (at its mounting bolts or somewhere else?) or the front "frame rail"? In the back would it go to the tension strut mount or the piece of frame that comes back and up from it, or somewhere else? Would it be beneficial attach at all or the above and some mounting plates on the floorboard, or would that be overkill? By the way I love overkill... which is probably evident from my long posts. Thanks.

 

[NJSHO]

The subframe connectors are weld on only. The connect to the "frame rails" under the car near the seats and at the flat spot under the rear tension arm bushing. If you do a search on the forum you can come up with build plans, installation pics, and opinions on the different styles (long vs. short.) Just remember that these things have some weight to them (mine are 32 lbs for the long style) so dont go too overboard.

 

[ohfosho]

how about warped rotors?

 

[93silverbulletSH0]

Yeah, my rotors are a little warped, but it is defiantly the abs kicking in. Only notice the warpage when braking at high speeds.

 

[crazy_canadian]

my ABS kicks in everytime I turn sharp and brake. Because I think when you take a turn at higher speed, the weight is transferred to one front wheel. So, the brake pressure are the same for both front wheels. Then, when you brake hard, since a tire is not sticking as much as the other on the road (weight transfert) the wheel will lock more easly than the other who have all the weight on it, and then ABS will simply kick in.

Correct me if i'm wrong.

 

[93silverbulletSH0]

Sounds like an excellent explanation to me.

 

[jammin]

its the wheel speed sensor, been there.

jason

 

[NoSlo]

Another reason that this will happen more when turning to the right is because the brake bias valve is linked to the left rear control arm. The brake bias valve is there as a poor-man's antilock; under hard braking the rear of the vehicle will lift up as weight is transferred to the front, and the valve is designed to reduces brake fluid flow to the rear brakes when the rear suspension ride height increases. The valve only works well when traveling in a straight line, and can be fooled when you are also turning when braking. When you turn right (transferring more weight to the left) the bias valve is compressed (opened) more than when going straight, which lets more brake fluid pressure go to the back wheels. When turning to the left and braking, however, the suspension on the left side will be in a higher position and will cut off more pressure to the rear brakes. There is therefore more rear brake pressure in a braking right turn and the ABS will kick in sooner.

The rear wheel on the inside of the turn will be the one with the least weight on it and will start to lock up first. On a braking turn weight is transferred to the front outside tire, with the least weight on the opposite corner's tire. On very aggressive braking turns with stiff springs and anti-roll bars, the rear inside tire can even lift off the ground and any amount of braking should activate the ABS system to keep the airborne wheel from locking.

A warped rear rotor could make the brake caliper tend to catch and lock more easily on the warped uneven surface. However, warping seems rare for the rear rotors unless something bad happened like a seized caliper or collapsed/plugged brake lines.

 

[ShoMotion93]

You might try pulling the ABS fuse in the main power box under the hood if you haven't already done so. This will give you a constant light,but maybe you can narrow it down between rotors and ABS. If the problem goes away with the fuse out I'd be looking at the rings and/or sensors. As a side note, grungy, sticky slider pins on the brakes have caused me simular aggravation as have sticky calipers. Been there,done that. Good luck

 

[Racer X]

my ABS kicks in everytime I turn sharp and brake. Because I think when you take a turn at higher speed, the weight is transferred to one front wheel. So, the brake pressure are the same for both front wheels. Then, when you brake hard, since a tire is not sticking as much as the other on the road (weight transfert) the wheel will lock more easly than the other who have all the weight on it, and then ABS will simply kick in.

Correct me if i'm wrong.

What he said.