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Thread: Wheel bearing-like grind under moderate+ braking?

  1. #1
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    Default Wheel bearing-like grind under moderate+ braking?

    Shortly after installing slotted rotors some time ago, I noticed a slight growl under moderate and heavier braking. It's far too rapid to be a warped rotor. I've had slotted rotors on other cars and never had this symptom before. It's almost like a heavy wheel bearing failure sound/feel. But I assume a wheel bearing would also present issues in other cases besides braking. It has gotten a bit more pronounced over time, but it's not a major annoyance.

    Is it just the rotor slots?
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    VIP Member BuildItYourSelf's Avatar
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    Probably junk pads. Maybe rotors. Or something wasn't installed correctly.

    Are they cheap rotors and pads?
    Old pads on new rotors?
    2008 GT-M. PBM, #885

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    Wagner thermoquiet pads on powerslot rotors. All new at the time.
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    How can I diagnose? The sound doesn't have clear directionality. One wheel isn't dusting any more than others. I haven't noticed any steering wheel vibrations. I think I can kind of feel it in the brake pedal, maybe.

    I don't think I could have installed anything wrong. It's easy enough to determine inside pads from outside pads. The rotor slots all sweep the right way.

    What else can I look for?
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    Hard to say. Maybe just the way they are.
    I have dba with hawk. They are a little noisy but nothing crazy.
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    Beyond Help Napalm's Avatar
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    what slotted rotor did you have before this.

    I find the DBA with the curved slots are rather smooth and quite vs the straight lined slots of other brands. So far that is.

    Question looking at the rotor do you happen to have grooves (circular ones) in the face? Or do you happen to have streaks in the face?

    Might be indicative of a harsh wear - which might be your notice. Mine growl a little here and there if I'm on them lightly. more pressure and it goes away. SOmething I've found to be normal with slotted rotors.


    If it was your wheel bearings - and it might be - jack up the suspect wheel (s). then take and try to twist the tire from the 9 and 3 oclock positions. IE try to turn it in and out of the car - if it wobbles around - try again from 6 and 12. Granted that could be things like ball joints - so look back there to see if anything else moves - but doing it from more than one position is indicative of a wheel bearing that's worn. In other words you can move the slop in the wheel hub. Its hard for me to describe right now but you'll know it when you feel it. The front ones are easy to replace.
    If Guns Kill people, then Spoons Cause Diabetes

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    I think all the slotted rotors I've done on other cars have been powerslot. All straight slots. I can't remember if the slots all went to the edge or stop short like these current ones. It'll be around Thanksgiving when I put the winter wheels on, so that'll probably be when I try wiggling wheels. I did take a look at the rotors quick the other day. I didn't see any grooving or streaks that seemed out of the ordinary. Maybe I'll take a closer look this weekend.
    Last edited by J Wikoff; 10-10-2017 at 07:35 AM.
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    I have had some of this on drilled/slotted rotors. A little more noise is a tradeoff. I did have one that the owner put RF on the LF and the LF on the RF...this was quite a bit of grinding noise!
    Yes for us larger guys that screw can be a pain!

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