Brake Problem Not Brake Related?

Discussion in 'Mechanics Garage' started by ZenkiGuy, Apr 18, 2019.

  1. ZenkiGuy

    ZenkiGuy New Member

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    I haven't taken the pistons apart and from what I know, the previous owner has never taken the calipers apart either.
     
  2. ZenkiGuy

    ZenkiGuy New Member

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    I have a new slide pin and oring installed freshly lubed. What other areas of the caliper should I check exactly? I've also lubed the slides that go in-between the SMC bracket bolt and mounting bolt. Both seem fine. How should I check if they're moving properly?
     
  3. ZenkiGuy

    ZenkiGuy New Member

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    I will take some videos and pictures today the best of my ability and you can see if it's what you're talking about. It's definitely metal on metal.
     
  4. Darth Vader

    Darth Vader New Member

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  5. Darth Vader

    Darth Vader New Member

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    In the above 11 is the pad retaining clip and 19 is the pin which goes thru the hole in the pad. Are these bits in good order ? Does 11 seat properly in the caliper body ?

    13 +12 are the caliper sliding pins , are these greased and the caliper moves freely?
    The pad poping out and the metal on metal noise in your video can only be related to the 4 above parts
     
  6. ZenkiGuy

    ZenkiGuy New Member

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    Sorry for the late replay(s).

    I had my SMC replaced yesterday and they greased all of those parts and they all move freely/in place. (11-14).

    Grinding is still here but now it is some what on the left side not just the right. It is worse in some spots of the rotors than. I've adjusted the axle some what and that helped. Here's a video that I made today (sorry for it being such crap quality). But the grinding is much less than before SMC replacement. Tomorrow I'm going to check the discs to see if they're warped.

    One thing I haven't check are the front wheel bearings but not sure if that would cause this issue as I don't hear any noise or anything while the calipers are off the bike.

    One question I had: Would bleeding the brakes help this issue? Maybe make the brake pads stay retracted? This is driving me insane now because I've checked everything and it all looks good.

    Thanks for the help, guys.

    Vide from today (can get better one)
     
  7. Terry Smith

    Terry Smith Member

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    I'm not sure that I am seeing any real problem there. Hearing some pad drag on the disc surface is normal, and from your video that looks like pretty good free rotation of the wheel. I'd also expect there to be minor variation in contact (and hence noise) over the disc surface as the wheel rotates and there is a spec in the service manual for maximum allowed run-out of 0.2mm, which is actually quite a bit.

    Before you did this video, did you press the brake lever and pedal to get the pads into their normal just-used position?

    There is a requirement in the manual to check the clearance between the disc and caliper after a wheel change using a feeler gauge, but I've never needed to do that. You should tighten the axle bolt, bounce the suspension, tighten the right clamp, bounce the suspension again, then finally tighten the left clamp. That allows the left leg to find its most natural rest position on the axle.

    Why would you need to bleed the brakes? Surely that was done when the SMC was replaced? Bleeding the brakes won't help the pistons to retract, they rely on the seals and release of fluid pressure back to the master. Bleeding just replaces old fluid with new and pushes air out of the system.

    One thing which can cause brakes to retract poorly (or not at all) is a clogged port in the brake master. If you open the master for the front brakes, on the floor of the reservoir is a thin metal cover, you can pick that out and under that is the tiny compensation port. When you release the brake pressure the piston moves back and uncovers that port which releases the line pressure back to the master. If that gets clogged, it will restrict the pressure release. There is a similar port in the rear master and also in the SMC; actually there are two in the SMC, one is built into the little plastic one-way cartridge. In the hand brake master you can easily see if that port is clogged, when you squeeze the brake without the cover in place a small jet of fluid will come up out of it (careful now).
     
    Last edited: May 2, 2019
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  8. ZenkiGuy

    ZenkiGuy New Member

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    To answer your question, the hoses are not installed on the caliper. So I haven't even bled the brakes yet. My concern is that I will go through the bleed process and still have a rubbing issue. But I'll go ahead and bleed the brakes, get them pads in position by squeezing brake levers, then go from there.

    I haven't bounced the suspension. By that you mean: Tighten axle bolt > bounce front suspension > tighten right clamp bolts > bounce suspension > tight left clamp bolts? I just put the wheel back on, axle in, and torqued them all down.

    I'll go ahead and loosen the bolts and bounce suspension. I'll bleed brakes and if still having an issue I'll check the masters. I just had the SMC rebuilt and cleaned out so I think I'm good there. Thanks!
     
  9. gips

    gips New Member

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    Not sure if related, not read all, but if your disk is draggin on the caliper, is the RIM put the correct way .................. if you put the rim hte wrong way it drags on the brakes....... it looks like its the same both ways, but its not. If you measure it the disks are biased a bit hence, you need to put the rim the correct way.
     
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