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Old 03-05-2003, 05:36 AM
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Unhappy Anti-lock rear brake dragging

Help,
Wifes 97 ply breeze Anti-Lock rear brake draging!! Only happening on one side.I have replaced Drum,Wheel cyl,Shoes and Hardware kit to no avail,Any ideas?? Never had this with my old cars and not be able to repair them!Local parts people said to do what I've done above and Garages say bring it in with the Big Wallet in hand.
Any help would be great!
Thanks,Rudy

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Old 03-06-2003, 09:33 AM
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Check out the sensor (hall effect?) on that wheel. If it's reporting a higher speed than the other wheels under braking, the computer might be giving it more pressure. Not sure exactly how they work on your particular car, but that's where I'd start. Look for sizeable debris on the inside of the rim, that could cause a hall effect sensor to report the speed doubled.
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Old 03-12-2003, 04:09 AM
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Stinkin-V8,
Thanks for the Info,will check it out.Not familiar with term " Hall Effect" but will look into it.
Thanks again,
Hotrod Rudy
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Old 03-14-2003, 07:26 AM
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A hall effect sensor is kindof like a proximity sensor.. You'd have something like a bolt on the inside of the rim and a sensor somewhere near it's path of rotation (say, on the brake caliper). As the bolt passes near the sensor, it reports a reading. Number of readings per second is the speed.

This is the way that I understand them to work, there will be some differences from manufacturer to manufacturer but I think the fundamentals are the same. Should give you a good starting point for your investigations.
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Old 03-15-2003, 05:37 AM
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Stinkin_V8,
Took it apart and found a magnetic sensor simular to the pick-up for a Distributor.I cleaned it and the veined rotor piece with no change.I replaced the Wheel cyl. because the heat build-up melted the seals on a recent Sunday drive.Is there a new way of bleeding brakes on Anti-Lock systems? Could improper bleeding cause this? This is the second wheel cyl.Diving under car to check for pinched brake lines today.Thanks for your help!
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Old 03-15-2003, 12:28 PM
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You first need to isolate the problem as being either mechanical or ABS.
  • You need to scan the system for code(s). Does the ABS lamp stay on after initial start-up? If you haven't access to a scan tool, usually an auto chain store (AutoZone) will offer scanning.
  • Jack the rear of the car up and rotate the tires by hand to see if they turn without about the same resistance. Apply the brakes. Rotate by hand again. Apply the handbrake and release. Does the right one now drag? Are the shoe(s) hanging on a worn spot on the backing plate not retracting fully? Does one brake cable not fully retract?
  • Drive the car. Jack it up again and rotate the tires by hand. Is it dragging now where it wasn't when cold? Open the cylinder bleed screw and if excessive fluid pressure is released, you either have a blockage in that circuit (possible collapsed flexline) or the ABS pump may be frozen causing that one particular wheel to have constant pressure.

You can still bleed most systems with vacuum. If you do bleed an open circuit and air remains, you may have to energize the pump with a scan tool or there is a low cost tool available to energize most pumps to bleed it the pressure way.

ABS systems should have the fluid changed every two years at the least as if the pump is never energized, the static fluid will cause corrosion in the pump which will lead to pump failure. It is a good idea also to panic stop the vehicle in an open parking lot a few times a year to keep the brake fluid from becoming stagnet in the pump.
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