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ABS Kicking in early - S4

michaelg1001 May 14, 2015

  1. michaelg1001

    michaelg1001 Registered User

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    Good morning chaps

    This has been bugging me for a few weeks now, when I pull up to a junction or roundabout etc, the ABS seems to kick in and brake really sharply just as I'm coming up to a stop.

    From what I've read, this seems to be a broken ABS ring, however on measuring the wheel speeds yesterday through VCDS, there didn't appear to be any fluctuation between the speeds of each wheel when travelling in a straight line.

    I've got no warning lights on the dash at all, could this just be an ABS sensor rather than a ring?
     
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  3. Blue_Thunder

    Blue_Thunder Registered User

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    I had this on my old car. I also tried a number of times on Vagcom to check the wheel speeds and never saw a variation. But sure enough, when I dismantled the car I found a rear ABS ring split. Trying to link to a photo, but for some reason ASN doesn't seem to like cut&paste of links on my phone.[​IMG]

    Someone suggested I should have logged the wheel speeds using the VAG-Scope option, as even tiny variances would be shown.
     
  4. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    yep it'll be a broken ABS ring.

    Sometimes you'll see it on VAGScope, but not always.
     
  5. michaelg1001

    michaelg1001 Registered User

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    Cheers guys.

    What are these like to replace? Can the rings themselves be replaced or is it the whole CV?
     
  6. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    You can get the rings on ebay.

    Not replaced one myself, probably need to heat it up to press it onto the CV.
     
  7. Kevinb5

    Kevinb5 Registered User

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    I had the same symptoms on my FWD,turned out to be grease on the ring from not being careful refitting the disc.
     
  8. Chriscooke

    Chriscooke Clueless!

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    If it's the same as on the tqs I had similar symptoms after refreshing my breaks and it turned out to be a dislodged abs sensor.
     
  9. michaelg1001

    michaelg1001 Registered User

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    I'll check that out first, I don't know whether it's purely coincidental that this started happening around the same sort of time I had the front arms replaced, so the garage that did it could have possibly knocked the sensor when disassembling or assembling.

    I'll be having the front brakes off soon anyway to put my B7 A4 brakes on (I say soon, they have been waiting a fortnight already!) so I'll hopefully at least diagnose which corner and what the fault is.
     
  10. Chriscooke

    Chriscooke Clueless!

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    It's simple to check, for the fronts you just need to put the car on full lock and give it a reach around ;)
     
  11. michaelg1001

    michaelg1001 Registered User

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  13. spartacus 68

    spartacus 68 Registered User

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  14. michaelg1001

    michaelg1001 Registered User

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    Cheers spartacus, that's a big help
     
  15. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    I think the rings for sale only fit the rear.

    The front ones dont really fail.

    And yes, the rear has sensors, theres one on each corner.
     
  16. michaelg1001

    michaelg1001 Registered User

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    Well I'm doing the rear control arms and eccentric bolts this weekend all being well, so I might get a ring ordered and hope I can do it there and then.
     
  17. Mad Cow

    Mad Cow Registered User

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    Before you go ordering parts try blasting out the area between the tone ring and sensor with brake cleaner and compressed air. Sometimes it's as simple as gunk built up on the sensor.
     
  18. michaelg1001

    michaelg1001 Registered User

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    Never got round to looking into this, spent so long trying and failing to do the arms.
     
  19. mojocvh

    mojocvh Registered User

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    Hmm I'm getting intermittent abs yellow with associated triple chime sometimes goes off weeks at a time but then seems to return when front nearside finds a pothole or road debris (grrrr) what would be the best way of tracing this? I wonder if it could be the bumps or sudden shocks affecting the abs pump unit or is the problem at the wheel???
    Hacked off Andy
     
  20. spartacus 68

    spartacus 68 Registered User

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    Getting the car scanned should pinpoint it. In my experience the front ABS rings rarely fail, but could very well be damaged sensor. If it's an avant, then the rear reluctor rings can break. If you don't want to get it scanned it's a laborious job to dismantle each drive-shaft and check ABS.
     

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