Mechanic Advice - brakes

Discussion in 'OT Driven' started by Coottie, Apr 25, 2008.

  1. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    So a couple of weeks ago, I took my bike to the dealership to change the brake pads. They said they did but I went out riding tonight and man....they were screaming at me. I mean it's worse than when I took it in.

    I'm wondering if they even changed them out in the first place. They are disc brakes so I shined a flashlight down there and the pads look tiny, compared to car brake pads.

    I don't know enough about motorcycle brakes to know if they even changed them or if they're just BSing me.

    I called them back and I've got an appt for Sat but I'm wondering if you guys have any other suggestions.

    Any ideas?
     
  2. Vtec44

    Vtec44 OG!

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    There are wear grooves on the pads that you can check. Typically, if it's approaching about 2mm then it's recommended that you change them.
     
  3. deusexaethera

    deusexaethera OT Supporter

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    I know on my mountain bike, new pads are silent and don't grip well until I do a few hard stops on them to break them in. Then they start screaming for a while, then after a few more hard stops they settle down.
     
  4. DoucheBag

    DoucheBag New Member

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    a lot of times if the rotor isnt resurfaced.. it will squeal. your pads dont wear %100 evenly.. so they leave grooves.. and with a brand new, perfectly flat pad... it has to wear around and down those grooves in the rotor.
     
  5. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    Well I specifically told them to change the pads, they charged me for them and said they changed them. I'm not sure I agree but well see.

    They told me that they aren't asbestos brakes anymore and so they are a bit noisy.
     
  6. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    I thought about this but these grooves are minor.
     
  7. DoucheBag

    DoucheBag New Member

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    doesnt really take a whole lot to make noise. even if you can barely feel them by running your finger across the rotor... it still may be enough to make noise.

    also, your old pads.. how long did you have them on? you should be able to notice wether or not new pads are on. most new pads are usually 1/2" to 3/4" thick.
     
  8. Junkie

    Junkie re-tarded OT Supporter

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    :rofl: not on motorcycles
     
  9. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    Yeah see...that's what threw me. The motorcycle ones are different, much thinner.

    Well I took it back to the dealership today and there was a different mechanic that helped me. He test rode it, looked over the other guys work then said they check out fine.

    He also told me that the noise is part of it because I have ABS systems on front and rear. Apparently this system hold the pads much closer to the rotor and that can cause the rolling squeaks I heard. He said the noises on braking are not out of the ordinary and that I probably got exceptionally lucky with my last set of brakes (lucky in that they didn't make much noise).

    So the noise is there but I guess it's getting less noticeable. I'm just glad he didn't tell me, "Yeah looks like the last tech didn't change them." lol

    Oh and fuck me it's awesome riding weather today!!! After the shop, I went on a nice long ride. I love riding when it's 60-65 degrees out. This is perhaps my favorite riding temp.

    Anyways, thanks for the feedback.
     
  10. Junkie

    Junkie re-tarded OT Supporter

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    Looking at the calipers off the Katana I have sitting here, it looks like the total distance between the pistons is about the width of a nickel, maybe a bit less. That's with the pistons pushed all the way back into the calipers of course. So yeah, there's never all that much pad.
     
  11. HattoriHanzo

    HattoriHanzo New Member

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    There is a metal shim that is supposed to go on behind the pad or it will be noisy. Make sure they put it on.
     
  12. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    Wait...a metal shim behind the pad would push it closer to the rotor right? Wouldn't that increase noise?
     
  13. Junkie

    Junkie re-tarded OT Supporter

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    The pad is touching the rotor, period
     
  14. Coottie

    Coottie BOOMER......SOONER OT Supporter

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  15. Junkie

    Junkie re-tarded OT Supporter

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    the brake pad is always in contact with the brake rotor, it just isn't always being pushed against it
     
  16. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    Hmm...I didn't think the pads always touched the rotor but I did think they were close. I guess I just assumed there was a tiny space between the pads and rotor while not braking. Obviously when braking they would be touching. But then again...I'm no mechanic.
     
  17. Junkie

    Junkie re-tarded OT Supporter

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    what would be pushing it back from the rotor when you weren't on the brakes?
     
  18. Coottie

    Coottie BOOMER......SOONER OT Supporter

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    When I used to work on my car, there was some gunk that you put on the back side of the pads. It was blue and sticky and it would hold the pad to the piston.

    Also I thought a spinning disk gave off air, like the Coriolis effect or something like that. Like when a CD spins, I thought there was a cushion of air created over the disk.
     
  19. deusexaethera

    deusexaethera OT Supporter

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    That's true, they're either metallic or ceramic. I think there's also kevlar, but they don't stand up to heat very well.
     
  20. deusexaethera

    deusexaethera OT Supporter

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    The brake levers use an open fluid system, wherein the first couple of millimeters of master-piston travel doesn't do anything because there's a hole in the side of the master-cylinder to let in extra brake fluid as the pads wear down. Once the master-piston moves past that hole, the system seals up and the master-piston pushes fluid into the brake line. When you let go of the lever, the master-piston retracts, and it pulls the slave-pistons back into the caliper a little bit, until the master-piston uncovers the hole in the master-cylinder again, and the system opens up to let fluid in/out again.

    It's that tiny bit of retraction when you first let go of the brake lever that pulls the pads away, provided that there is a retraction spring pushing the pads away from each other. (EDIT: Or, you can use the sticky goop someone else mentioned, to glue the pads to the slave pistons.) Because of the leverage ratio between the master cylinder and slave cylinders, the pad retraction isn't enough for you to see without a microscope, though.
     

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