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ABS/Brake pulsing?

Discussion in 'A4/S4 forum(B5 Chassis)' started by fallmonk, Jul 8, 2012.

  1. fallmonk
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    fallmonk Turbo Sport

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    Hi folks quick question ,
    recently replaced all brake disks(inc exciter rings) n pads, plus a O/S/R caliper
    brakes working fine and ABS light coming on and going off as ment to on start up

    BUT as i come to a stop i get a slight pulse as if Abs not working ? it only does this as it basicly comes to a stop . every other time its fine ???????
    any ideas folks ?
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  2. spartacus 68
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    spartacus 68 Member

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    Is it a quattro? The rear ABS reluctor rings can split - and symptoms are exactly the same.
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  3. PAULF
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    PAULF Active Member

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    :iagree:

    Like this

    [​IMG]


    You may find it has just picked up rust flakes on the sensor, but I've had 3 go so far on my two cars.
    You can find the rings to change I got one mine from ABS Reluctors (I think!) but it was expensive. The other two I fixed with oxy-acetylene and a jewellers torch.

    [​IMG]

    To change one, you need to clean the driveshaft properly with a file, heat the ring to dull red and pop it on. It shrink fits. A duff welding job will now crack!!
    Last edited: Jul 8, 2012
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    AudiA4B596 likes this.
  4. AudiA4B596
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    AudiA4B596 Member

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    Its probably one of the abs sensors hasnt been put back all the way in, I had the exact same problem two weeks ago when i git new brakes put on, its a delicate job though, you need to locate and find the one or more inncorrectly inserted senors, they are right next to the brakes and its a job that is supposed to be done by hand once you have the wheel off, i fixed it myself so you shouldnt need to take it to a garage! Good luck, let me know how you get on!!!
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Yeh its either a split reluctor (though i think you've indicated in your post that you've replaced those?) or a sensor isnt quite seated fully home.

    if you can find someone with vagcom, you might be able to find the faulty wheel using its measuring blocks mode.
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  6. murran
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    murran Active Member

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    agreed with the measuring blocks/actual values, select each wheel and roll the car along at like 2-3mph. i bet ones reading 0 untill about 5 mph. sensor just needs pushing in fully home then pulling back ever so slightly.

    these early systems, the air gap is adjustable and is pretty critical, the further away the sensor is from the abs ring the weaker the signal is.
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