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XJ1100 brake pad - total shim or partial shim?

Discussion in 'XJ Technical Chat' started by KA1J, Jun 1, 2011.

  1. KA1J

    KA1J Member

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    Location:
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    I'm kind of stuck in limbo, not sure what to do.

    I'm trying to understand if this is the way the brakes are supposed to be or if parts are missing. The shim for the front brake pad does not seem proper.

    The front R. brake only had one pad shim and it's a diagonal shim .015 thick which only covers 1/2 of the piston. Neither of the left side pads had a shim of any kind.

    Here's the one existing pad shim and pad next to it (you can see the residue left where the caliper was resting):
    [​IMG]

    Here is the shim on the pad. Notice how the piston had been pushing on the pad itself as well as the shim, the piston only hit 1/2 the pad.:
    [​IMG]

    And here is the passive pad on the inside of the caliper which contacts the caliper itself:
    [​IMG]

    Question 1: The shim seems to be only 1/2 of what should be there. Is there a 2nd part of a shim that is missing?

    Question 2: If I were to cut to form, the laminated stainless shim material used on car disc brake pads which attaches via an adhesive on one side and place that on the entire back of the pad, would that work well to reduce squealing? It's laminar construction is designed to be highly reflective to heat. The local brake shop gave me quite a bit of this stuff.

    Question 3: On the Left caliper, there was a very thin rectangular shim plate which was recessed inside a much thicker stainless plate on the top section. The shim was .005 thick. On the right caliper there was no thin shim. (In an earlier post it was noted sometimes this shim is missing. I wonder if this ultra thin shim is installed at the caliper maker to meet tolerances only and has nothing to do with heat or noise.

    Is this ultra thin shim used for leveling or for heat/noise issues? I'm not sure if I should try and form a matching piece for the right side or not.

    Lastly, if someone could post a photo of the shim on the front pad on a XJ650J I'm missing mine. When I bought new pads for it last year I didn't know to look for the shim & the new pads didn't come with any. Or... as I questioned above, could I just put that automotive stainless shim on it? When I use the front brake it squeals terribly & nothing I did including chamfering & applying anti-squeal paste helped in the least.

    Thanks!
     
  2. pirok

    pirok Member

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    As far as i know it's about noise - howlin and rattling.
    On the active pad the shim should be fitted to the upper half.
    In the bottom of the caliper there should be a anti-rattle shim.
     
  3. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Answer 1: Yamaha pad shims look like that, nothing is missing.

    Answer 2: If you want to do that, go ahead. But "mirror-match" the "half-coverage" characteristics of the shim in the pic. Then it should work fine. That strange "halfway" configuration is part of the anti-squeal magic and I haven't quite figured out why yet.

    Answer 3: The actual shim between the larger shim plate and the holding block ("upper" part of caliper) is there to take up slack and keep the caliper from rattling/hanging from the sliding pin. There may not have been one on the other caliper; I've never actually seen one "in the wild" just the plates. A shim may not have been necessary on the other caliper; or it is missing like you said.

    As for the 650, see answer #2 above.
     

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