Help! Brake vibrations.

quartersquarters Council Member
in Suspension, Braking & Wheels
Well I've been having brake vibrations between 90km - 65kmh. Anything over/under that it's buttery.
Last week i put brand new rotors on, and the vibration remained.
Yesterday I took an old set of rotors to get machined, and took off the brand new ones i put on.
This is what the front left brand new rotor looks like after 2 weeks.



if you look, there is a strange ring of what looks like a grab/release/grab/release. zoom in on the pic, the left of the pic really shows it off.

When I put the new machined rotors on, it was great and smooth for the 1st 100km-0 brake for bedding in the pads, after that it starts feeling like poo again.

What's going on here?

I'm going to pull my hair out.

Comments

  • Ryanthegreat1Ryanthegreat1 Wagonist
    Huh that is an interesting harmonic you have there.

    Are you bedding in the rotors and pads each time?

    http://stoptech.com/technical-support/technical-white-papers/bed-in-theory-definitions-and-procedures
  • greenteagodgreenteagod Moderator
    With the new rotors/machined rotors, are you using the same pads as before? There's definitely something there causing hot spots. Maybe you have a crap set of pads. What pads are you running? Some run hotter than others, maybe the pads themselves are overheating the rotor.

    Is that happening on both sides? Or is that just the front left causing the problem?

    If you look at the pad is the wear on it even or is it wearing on one side faster than the other?
  • quartersquarters Council Member
    I always follow the bed in procedure. using axxis ultimate pads which i really like. Only the front side of the rotor did that. im stumped! its a lot of vibration in the wheel, none in the pedal.
  • Ryanthegreat1Ryanthegreat1 Wagonist
    Both left and right rotors do this?
  • greenteagodgreenteagod Moderator
    I think I might be using some Axxis pads myself. I'm just wondering if at some point the old rotors got heated up and cooked the pads and then the cooked pads are leading to more cooked rotors. I didn't catch if you said when you switched rotors if you're using new pads or not. If new pads and rotors then I'm a bit stumped as well.

    Any wheel bearing play? Just thinking if that were to get wiggly and cause things to start binding up in a funky fashion. I'm just guessing at this point though.
  • quartersquarters Council Member
    the pads were not replaced with the rotors. Only the front left rotor is doing this. I dont notice any bearing noise or play.. So frustrating.
  • Ryanthegreat1Ryanthegreat1 Wagonist
    Are the caliper slide pins in good working order? Maybe the caliper is getting cocked and causing a vibration.
  • greenteagodgreenteagod Moderator
    Yeah definitely check the slide pins, but I know I've seen a cooked pad before so using a cooked pad on a new rotor generally isn't the greatest so with the cost of pads not being that much I'd consider a replacement or at least have any junk shaved.
  • LowFlyin'LowFlyin' Moderator
    Check the slide pins, I clean and regrease mine every time the caliper comes off. Check the caliper and piston to make sure everything is square and try compressing the piston all the way in.

    Also, check your pad for anything that looks out of place and your hub for movement.
  • MrJayDMMrJayDM Wagonist
    Anything I have wheel vibrations this is the check list I go though.
    Not in any order!!

    The Check List!!
    1. Front End Alinment
    2. Tires Balance
    3. Rotors (warped)
    4. Brake Pads (ware even)
    5. Calibers (Check the slide pins)
    6. Hub (check for a bent hub)
    7. Bearings (Any Play)
    8. Axle (bent or bad CV)
  • quartersquarters Council Member
    will check pins tomorrow. Should they have any slop in them. I recall having a tiny bit.
  • LowFlyin'LowFlyin' Moderator
    The pins shouldn't really have any perpendicular play. If they do, add more grease! Fill the hole until all of the air is pushed out when you push the pin in.
  • quartersquarters Council Member
    Ok, i'll pull the pins and add a shitload of grease.

    I did the rack-end bushing as well, need to adjust the pinion gear too.
  • greenteagodgreenteagod Moderator
    Update????
  • quartersquarters Council Member
    Update:

    I can't say exactly what did it but I have managed to get the vibration to a minimum. To the point where I don't AVOID using the brakes anymore.

    - swapped that rotor out of course
    - took the pads out, sanded them down on a sheet of 150grit, sprayed with brake clean
    - greased the slide pins heavily.
    - pushed the caliper piston all the way in as to maybe loosen it a bit if it was sticking.
    - adjusted the pinion gear on the rack
    - got an alignment.

    i wish i could say which of the above did the most to help, but i don't know. it's not 100% perfect, but it's pretty good.
  • quartersquarters Council Member
    Well that was a waste of time and money...

    I went for an aggressive mountain blast and by the time i was done the problem is back. The new rotor is starting to look very much like the one i pictured in the first post. Something is F*CKED!
  • LowFlyin'LowFlyin' Moderator
    Replace the caliper.
  • quartersquarters Council Member
    405.jpg

    the replacement rotor doing it's thing again, a bit hard to see because of shadows and it's still on the car, but you get the idea.
  • greenteagodgreenteagod Moderator
    Yep, at this point I'm with Lowflyin' replace the caliper, they're cheap enough.
  • LowFlyin'LowFlyin' Moderator
    quarters wrote: »
    the replacement rotor doing it's thing again, a bit hard to see because of shadows and it's still on the car, but you get the idea.

    Looks like uneven pad transfer.

    Overheating the brakes can cause this.

    A stuck/sticky caliper will cause overheating.

    I'd suggest trying a new caliper.
  • quartersquarters Council Member
    Getting a new caliper tomorrow.


    I ran another test today out of boredom/curiosity.
    I had a set of OEM replacement pads, at about 99%. scuffed them up and put them on. They barely fit with the full thickness rotor and thick pad.


    So i take it out for a spin, driving along fine, hit the brakes, everything seems fine, actually firmer than before. So i'm thinking it's fixed.
    Make it about .5kms before i start smelling burned brakes...
    stinking real bad.
    I turn around, hit the brakes a few more times thinking it will vibrate like crazy. It never did. But mad stink.
    Pull it into the garage after not even applying brakes for at least 2kms, and it's raining. Couldn't even grab a spoke of the rim, so hot.
    So it would appear that the caliper definitely stuck and the brakes were dragging even without applying them. The rotor was a nice blue color, but no spottiness.
    I let everything cool off, put my 45% axxis pads back on, took it for a spin, vibrations back and the spots on the rotor come back.


    Caliper replacement tomorrow.
    Thanks everyone, i will let you know how it goes.
  • quartersquarters Council Member
    fail. caliper replacement did not fix my problem.
  • greenteagodgreenteagod Moderator
    Well with that done I'd say the hub is in question. You never did say if you addressed that. How long ago were the hub bearings replaced, was the hub assembly replaced as well? You'd think that would be something that could have been ruled out with an alignment but sometimes they don't check that crap.
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