severe braking vibrations and soft pedal on 05 Impreza Outback Sport

Discussion in 'Subaru Impreza' started by Dave Botsch, Aug 29, 2007.

  1. Dave Botsch

    Dave Botsch Guest

    So, the car is just over three years old with about 20K on it (yes, I
    don't drive that much).

    While there has always been some vibration when braking (presumably due to
    the antilock brakes grabbing and releasing), I just noticed that even if I
    brake a little bit, say to slow down 5 mph from around 55 or 60mph, there
    is severe vibration that I'm even feeling in the steering. Could this have
    anything to do w. my pads starting to get close to the replace point or
    tire rotation (just done)/etc? Normal ride/coast feels just fine, and at
    lower speeds, not nearly (if any) vibration -- car also seems well aligned
    and stays straight when braking/accelerating/letting go of wheel).

    I think this is not normal, but need to know what to tell them since they
    will probably tell me everything is within spec and it's normal for this
    age of pads/etc.

    Since the NYS annual inspection about two years ago, when I picked up the
    car after that inspection, I discovered that I suddenly had to press the
    brake pedal down much further before the brakes would physically engage
    (the brake light still lights as soon as the pedal is barely tapped)
    whereas before that inspection, the brakes were quite tight (I did not
    have to touch the pedal much at all for the brakes to slow the car). Went
    back to the dealer and told them, they checked, told me that the distance
    to pressing the pedal was normal, everything was within spec, and that if
    I pumped the brakes a little it would get better (which it does, but it
    always goes back down to that point after a while and I've occassionally
    felt the pedal sink down while stopped back to that point). It's never
    gone below having to press the brakes more than that.

    So, they claim everything is right... but clearly something changed during
    that one inspection (which included checking the brakes).

    Any thoughts on either or both of these issues w. things I can tell them
    to check?

    Thanks!
     
    Dave Botsch, Aug 29, 2007
    #1
    1. Advertisements

  2. Dave Botsch

    AS Guest

    It sounds as if your rotors (discs) need to be resurfaced. Since you
    drive so lil, i think the rotors may get rusty between uses and cause
    all sorts of issues. At 20K i doubt you need new pads.

    The vibration when slowing down the 5 mph you say, could be warped
    rotors, uneven surface on them, alignment (doubt it) or suspension wear
    (really doubt it).

    Warped discs or air in the brakes hydraulic system may cause the pedal
    to feel soft.

    In NY, do you have the car inspected at a mech. shop, right? Was it the
    dealer that you refer to? Tampering? Do they have the equipment to
    test all wheel drive vehicles? Was the awd disconnected during the test?

    Good luck!
     
    AS, Aug 29, 2007
    #2
    1. Advertisements

  3. Dave Botsch

    .._.. Guest

    No.

    -- not specifically to poster --

    HEY GUYS. WITH MODERN CARS, YOU REALLY REALLY SHOULD LEARN WHAT ANTI-LOCK
    BREAKS ENGAGING FEELS LIKE. GET OUT FIND SOME GRAVEL IN A SAFE AREA, GET
    SOME SPEED AND STOMP ON THE BREAKS.

    THIS LITTLE BIT OF EDUCATION CAN SAVE YOU PANIC WHEN IT HAPPENS IN REAL
    LIFE, WHEN YOU SHOULD BE THINKING ABOUT GETTING OUT OF WHATEVER SITUATION
    YOU ARE IN.

    -- end not specifically to poster --

    Knowing what ABS does is as fundamental to driving a modern car as locking
    it in the parking lot is.

    I just noticed that even if I
    I'd suspect rotors.
     
    .._.., Aug 29, 2007
    #3

  4. There is a good chance that your caliper has frozen. It's
    supposed to be able to float over the disk, and if it quits doing
    that, you'll get the symptom you describe. That, or a warped
    rotor, or both.

    OBTW, anti lock breaks don't kick in under normal driving
    conditions, unless you normally go into panic stops.
     
    Steve Daniels, Aug 29, 2007
    #4
  5. Dave Botsch

    Dave Botsch Guest

    With respect to rustiness, we do have the salt on the roads up here in the
    winter. And, the car is stored outside, unfortunately.

    I would say it seems like it's somewhat worse since the last NYS
    insepction (which was combined with a regular subaru maintenance interval).

    I only take my car to the local Subaru dealer - for any repairs, subaru
    maint. intervals, and for New York state inspections.

    The pads are getting down there... I would have to look, but I believe
    they are now under 50%.

    Are the rotors something that can be easily tested? The stuck caliper
    mentioned by a previous poster?

    and any thoughts on the "soft" break pedal?

    thanks.
     
    Dave Botsch, Aug 29, 2007
    #5
  6. Dave Botsch

    Dave Botsch Guest

    Hi.

    While I appreciate the suggestion, the brakes do feel significantly
    different as compared to braking at high speeds versus low speeds. And
    while I do, every year, take the car to a parking lot to remind myself of
    how it responds and skids to braking at low speeds (say 20 mph) on snow
    and ice, I'm not about to try that test on any surface of slamming on the
    brakes at 60mph.

    Yes, even normal stopping coming up to a stop sign at 30mph, a nice and
    gradual stop, it's not a completely smooth stop as if the brakes are not
    grabbing the wheel consistently (and back when I had a GM car, the then
    dealer told me that that was a symptom of the antilock brakes constantly
    grabbing and releasing a bit) -- not sure I buy it since I thought
    antilock brakes were only supposed to really release if the wheels were in
    danger of a skid.
     
    Dave Botsch, Aug 29, 2007
    #6
  7. Dave Botsch

    Dave Botsch Guest

    thanks for the response!

    Let me ask the following:
    1. would any of these symptoms be related at all to what I described as
    the brake pedal softening (having to push it down further) -- as if when
    they took it apart for that first inspection it never got put back
    together quite right?
    2. Presumably, there's some adjustment that tells the antilock brakes when
    they need to do their thing -- could that be off?
    3. Warped rotor/stuck caliper - can one lead to the other, and is it easy
    for the dealer to test for these?

    Thanks!
     
    Dave Botsch, Aug 29, 2007
    #7
  8. No, but it's certainly a serious issue in its own right.
    Got me. But if you drive on salted roads, the chances of your
    calipers being frozen are a lot higher than your ABS going on the
    fritz.
    It would be unusual for a rotor to be warped at 20K miles, but
    the salt may have done Bad Things to your brakes. It is easy for
    the dealer to check. All he needs to do is test the rotor for
    runout, and while the rotor is off for that test, to see if the
    caliper can be slid back and forth a bit.

    Were I you, I'd get a complete brake inspection and fix whatever
    is wrong. If you motor quits, you can't go. If your brakes
    quit, you can't stop. Guess which condition will get you into
    the most trouble?
     
    Steve Daniels, Aug 30, 2007
    #8
  9. Good post except rotors can have uneven pad material deposited in the
    first mile. Whether someone at the dealership is responsible - who knows?
    Assuming you are not a do-it-yourselfer, I'd suggest taking your
    concerns and your car to another dealership or GOOD independent
    mechanic/brake shop.

    A single hard stop - followed by holding the car stationary for a few
    minutes with the brake pedal, CAN create what most folks call 'warped'
    rotors. check;
    http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

    Carl
     
    Carl 1 Lucky Texan, Aug 30, 2007
    #9
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.