940 brake vibration

Discussion in 'Volvo 940' started by Tony Stanley, Aug 5, 2003.

  1. Tony Stanley

    Tony Stanley Guest

    I changed the disks on my 1995 940 Turbo SE Estate front and back over a
    period of a few months. They seemed OK at first but now I am noticing a
    pronounced vibration under braking at lowish speeds with the steering wheel
    oscillating back and forth.

    Are these brakes suseptable to warpage and I need to select a better
    supplier, or could I have assembled them poorly? I did clean up the
    surfaces before assembly. Could it be something else?

    I have modified the turbo for more power, and may have been driving the car
    quite hard at times.
     
    Tony Stanley, Aug 5, 2003
    #1
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  2. From a point at sea, to the circles of your mind, this is Tony
    Stanley:

    People here have suggested that over tightening the wheel nuts
    promotes disc warpage - I've never had a problem on my 740. But warped
    brake discs are more likely to be felt through the brake pedal than
    the steering. I think I'd be having a look at wheel bearings or track
    rod ends.

    Jack the wheel off the ground and grasp it at 6 and 12 o'clock; try
    rocking it. Ideally you shouldn't feel any play. Don't confuse it with
    steering or suspension movement. If there is any play, suspect wheel
    bearing.

    Do the same at 3 and 9 o'clock. If you can feel movement, have someone
    put the foot brake on and repeat. If the movement is still there,
    suspect track rod end. If it disappears, suspect wheel bearing.


    --

    Stewart Hargrave

    A lot faster than public transport


    For email, replace 'SpamOnlyToHere' with my name
     
    Stewart Hargrave, Aug 6, 2003
    #2
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  3. Tony Stanley

    Mike F Guest

    While it's possible that the disks are indeed warped beyond specs, what
    could be happening is the minor (below spec) warpage that is normal can
    be amplified if the bushings at either end of the strut stay (aka
    caster) rods are worn.
     
    Mike F, Aug 6, 2003
    #3
  4. Tony Stanley

    Stuart Gray Guest

    I remember reading somewhere, probably here, that heating up the brakes a
    lot, then sitting on the brake causes transference of material from pad to
    disk. Apparently if you look at your disk (both sides) you may see an
    outline of the pad left on the disk. Sort of like leaving an iron on a shirt
    I suppose. This can cause snatching. I wish I could remember the website.

    Stuart.
     
    Stuart Gray, Aug 6, 2003
    #4
  5. Tony Stanley

    Mike F Guest

    Most of the time what I see is this effect caused by rust. Where the
    pads are sitting is protected, the remaining unprotected surface rusts.
    This is not a problem on a car driven every day, or stored in a garage,
    but can cause a really uneven surface on an infrequently driven car that
    sits outside, especially in the rear.
     
    Mike F, Aug 7, 2003
    #5
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