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  1. #1
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    We the people ... How to use Avid 185mm rotor with Hayes Hydros

    I just figured out how to use the Avid 185mm (7") disc and mounting bracket with a Hayes hydraulic caliper. If one simply tries to mount the Hayes caliper to the Avid bracket then the caliper will hit the bracket, but if one picks up a set of "cup and cone" washers for each side of the caliper flange then the caliper will be spaced correctly and no longer hits the bracket. You also get the benefit of multi-axis alignment the same as how Avid mounts their calipers. Any bike shop should have tons of the cup and cone washers- they are the washers used on each side of brake pad studs for V-brakes or cantilevers. Anyway a picture is worth a 1000 words so here is a close up of one side of my Hayes caliper mounted using the cup and cone washers. Also note that longer mounting bolts will be needed.


  2. #2
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    Quote Originally Posted by VT no 1 2 or 3
    I just figured out how to use the Avid 185mm (7") disc and mounting bracket with a Hayes hydraulic caliper. If one simply tries to mount the Hayes caliper to the Avid bracket then the caliper will hit the bracket, but if one picks up a set of "cup and cone" washers for each side of the caliper flange then the caliper will be spaced correctly and no longer hits the bracket. You also get the benefit of multi-axis alignment the same as how Avid mounts their calipers. Any bike shop should have tons of the cup and cone washers- they are the washers used on each side of brake pad studs for V-brakes or cantilevers. Anyway a picture is worth a 1000 words so here is a close up of one side of my Hayes caliper mounted using the cup and cone washers. Also note that longer mounting bolts will be needed.
    Actually, If you are using the Avid 185 mm (7.28346") bracket you do not want to use the washer stack. The washers will move the caliper too far from the rotor.
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  3. #3
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    Quote Originally Posted by shiggy©®™
    Actually, If you are using the Avid 185 mm (7.28346") bracket you do not want to use the washer stack. The washers will move the caliper too far from the rotor.
    I have to use the washer stack or the caliper will hit the bracket. The rotor in the picture is a 6". I will update with pic of the completed installation once I get enough longer mounting bolts.

  4. #4
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    A much easier way.

    There's a much easier way.

    Get a rear hayes adaptor and bolt it on the front. This gives you the spacing for a 185mm rotor with standard hayes parts (other than the rotor of course).

    Multi-axis mountings are a waste of time with a hayes hdyraulic. They have swivelling pistons which self align the pads to the rotor anyway.

  5. #5
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    Quote Originally Posted by Dougal
    There's a much easier way.

    Get a rear hayes adaptor and bolt it on the front. This gives you the spacing for a 185mm rotor with standard hayes parts (other than the rotor of course).

    I will check into using the rear Hayes mount on the front. Also noticed and then measured the Avid rotor as compared to the Hayes rotor and the Avid rotor is thicker- maybe another problem area since the Hayes have pretty tight tolerances.

  6. #6
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    Quote Originally Posted by VT no 1 2 or 3
    I will check into using the rear Hayes mount on the front. Also noticed and then measured the Avid rotor as compared to the Hayes rotor and the Avid rotor is thicker- maybe another problem area since the Hayes have pretty tight tolerances.
    I know people who've ridden hayes with 160mm avid rotors without problems. Just check for clearance in the back of the caliper before you ride. I can't remember if the hayes adaptor on the front fits a 180 or a 185mm. If it's a 180, then you may need a washer between the caliper and the adaptor for space.

    Good luck
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
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  7. #7
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    Thanks for the tip.

    Using the rear mount on the front along with the cup and cone washers does work (I needed to use the washers since the caliper was canted when using the rear mount up front) and caliper alignment came out OK.

    The thickness of the rotor is a problem for my setup- the Avid rotor is 3/1000 ths thicker than the Hayes rotor- I know it does not sound like much but my Hayes always self adjust to leave about 12/1000 ths total gap between the rotor and pads. Take away 3/1000 ths and add a little rotor warp makes setting up without the rotor scraping when the brakes are cold impossible. Just the expansion of the brake pads and seals from the heat is enough to make my Hayes scrape when hot and they stop scraping once they cool down- the scraping doesn't really bother me as long as it goes away when the cool- the Avid rotor would scrape when cold and really scrape when hot- so I went back to the 6" Hayes rotor.

    At least I had a relaxing afternoon wrenching on the bike and it is already for a nice ride tomorrow.

  8. #8
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    Quote Originally Posted by VT no 1 2 or 3
    my Hayes always self adjust to leave about 12/1000 ths total gap between the rotor and pads.
    Actually your pads self adjust to be always the same distance clear of the rotor. If you push the pads/pistons right back, then install the new wheel/rotor then it'll come out right.
    The rotor width is only a problem if it's fouling on the caliper body.

    If you're getting heat expansion then you have a bleed problem. Either air or too much fluid in the system. Yesterday I got mine hot enough to colour an 8" rotor. The pad gap and lever position stayed right where they should.
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  9. #9
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    There is nothing wrong with them- no bad bleed, no air in the system. The problem is the operator who forgot to push the pistons back into the calipers before using the thicker Avid rotor.

    As for scraping while hot- even my mechanical Avids (no fluid here to expand) will scrape after a long downhill run- heat causes expansion in the pad material, metal of the caliper, etc. and if tolerances are tight enough a scraping can be heard when the materials have expanded.
    Last edited by VT no 1 2 or 3; 04-04-2004 at 10:39 AM.

  10. #10
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    Sorry to pick up such an old thread, but I am now also looking to install a 7inch rotor on the REAR of my VT (having burnt out a 6, and given possible fitting issues with an 8) using existing Hayes HFX9 Caliper.

    There is plenty of conflicting opinions out there, has anyone actually made it work??

    My lBS says the Avid 7' adapter wont fit with my hayes HFX9 caliper, not sure if this is right or wrong. Certainly contrary to "Tonys" opinion on a recent thread title "Hayes 180mm rear?"

    Others also suggested using a Hayes 203 FRONT adapter, are there different specs of these??

    Is there any difference in fiiting 180mm v 185mm?

    Given I have pay to order stuff in, I want to know what will work?

  11. #11
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    The front 203mm adaptor will work with a 185mm rotor on the back. But once again it's wise to check for clearances before you go riding.

    You'll need to get the 203mm adaptor for a QR fork, the 203mm adaptor for a 20mm axle fork is 5mm too wide. Not a problem if you have a milling machine handy.

    Quote Originally Posted by Gaunty
    Sorry to pick up such an old thread, but I am now also looking to install a 7inch rotor on the REAR of my VT (having burnt out a 6, and given possible fitting issues with an 8) using existing Hayes HFX9 Caliper.

    There is plenty of conflicting opinions out there, has anyone actually made it work??

    My lBS says the Avid 7' adapter wont fit with my hayes HFX9 caliper, not sure if this is right or wrong. Certainly contrary to "Tonys" opinion on a recent thread title "Hayes 180mm rear?"

    Others also suggested using a Hayes 203 FRONT adapter, are there different specs of these??

    Is there any difference in fiiting 180mm v 185mm?

    Given I have pay to order stuff in, I want to know what will work?
    Owner of www.shockcraft.co.nz and NZ Manitou Service Agent.
    www.dougal.co.nz Suspension setup & tuning.
    SPV Devolve

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