weird: abs kicks in

[rjcj]

Hey, question for you all...

I went off the road recently in a snow storm and had to get some work done on my '94. Specifically a new driver's side front spindle, wheel and alignment.

I just got it back and the abs kicks in right before I'm about to come to a complete stop. Its kind of tough to describe but I can just be driving along and hit the brakes, and I slow down alright, but right before I come to a complete stop, the anti-lock kicks in. It definitely wasn't like this before I took it in. I get no idiot lights.

Can anyone explain this? Has this happened to anyone else? Could I have messed something up in the ABS system in my accident? Could they have screwed something up in the shop?

TIA
Ron

<small>[ March 25, 2003, 02:36 PM: Message edited by: rjcj ]</small>

 

[jelloslug]

Sounds like the sensor ring is cracked. There is a ring that looks like a gear, that what the ABS sensors uses to see if a wheel is locked up. If there is a crack and one gap is larger that the others, it thinks the wheel is locked and blamo! ABS kicks in. If the gap gets wider it will kick in at higher speeds, so you might want to get it fixed soon.

 

[rjcj]

Any idea how much it would cost to fix this? I'm taking it to the shop tomorrow and I'm definitely on a limited budget.

Ron

<small>[ March 26, 2003, 04:26 PM: Message edited by: rjcj ]</small>

 

[Rob94]

When mine cracked, I just replaced the entire halfshaft which came with new sensor rings. I believe it was $65 for the part from NAPA. Autozone.com also has them. Relatively simple to replace.

 

[jasonty]

Also, if there is a bunch of grease and dirt on the ring, it could give the WSS (wheel speed sensor) inaccurate measurements. The ring is metal, and it makes a magnetic contact as it spins with the WSS, kind've like the crankshaft position sensor. If there is a bunch of dirt covering up the ring, it could give the ABS computer a false reading, and lock up the brakes.

 

[RStalveyARFF]

also the CV axle locknut can be loose. Check that first, it should be torqued to around 200 lb ft.

 

[Paul T]

I have a 1990 SHO and recently my front drive shafts had to be replaced. When I braked the wheel shook violently. When the mechanic replaced both drive shafts, he also turned the front rotors and installed new brake shoes (front).

I had the same experience with the brakes disengaging just before a normal stop.

I took it back and he found everything tight so he tried calipers and brakes hoses.

The problem still was there. Then we found the instrument cluster has some loose connections. He pulled the panel and tightened the connections. (This brought back my tachometer which had ben dead for 2 years..). Now the ANTI-LOCK lamp worked and cycled normally.

He took it out and drove it for 1/2 hour. The problem did not occur again.

I used the car last night and drove without incident until I got home.

When I pulled in the driveway, the brakes acted up again. This time it really felt weird and I noticed I had the wheel turned over in a hard left at the time. When I backed up and drove straight and applied brakes, I had the same "brake release" problem.

Does this sound like the same problem with the sensor as reported above?

Any info greatly appreciated..

Thanks

Paul

 

[Doug Waschenko]

95% of the ABS lockup problem is caused by a cracked "exciter" ring.
They generally aren'tserviced sererately, but they come on rebuilt axles.
This is a very common problem.
Mine was damaged as delivered new. It came off of the transporter that way.

 

[89 black SHO mtx]

here is an interesting problem! i ran into an abs problem similar to this awhile back on a chevrolet. it turned out to be the hub bearing was bad and when the wheel was turned the bearing moved and the exciter ring pulled back from the sensor. a very weird problem as this was the first and only time i had ever seen this happen. but after readinng some of the posts it started to sound like the exact complaint the customer had. so in short check your hub bearings for excess play.

 

[rjcj]

Turns out it was the sensor ring. The part ended up costing $110. ouch!

Ron

 

[Paul T]

My mechanic replaced the axle unit (includes the sensor ring) at no charge and replaced the sensor unit (no labor charge).

The car seems to be fine now. Won't know until I have a chance to drive it for a few days.

Thanks for the help.

Paul