turning brake rotors ?

Discussion in 'The Garage' started by Bruce Caldwell, Apr 5, 2007.

  1. Bruce Caldwell

    Bruce Caldwell Long timer

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    Can M/C brake rotors (1100GS rear in this case) be turned, for example, at an auto parts store? You know, the ones that say "we turn drums & rotors". Or does it have to be done by a speciaty shop?
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  2. Schtum

    Schtum Free Genie

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    I would guess that you can't do it at all. Motorcycle brake discs (rotors) are much thinner than car ones. I suspect taking any meat off them to resurface them would take them below the service spec. thickness.
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  3. Poolside

    Poolside Syndicated

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    Have them ground at a shop that resurfaces flywheels.

    Figure a way to fixture them, maybe t-slot clamp from inside the 'circle', depending on work table on the equipment the shop has.

    Be sure the operator verifies with a dial gauge that the rotor is fixtured 'flat' before grinding. Especially on the second surface.

    - Jim<BR><BR>
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  4. GreaseMonkey

    GreaseMonkey Preshrunk & Cottony

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    Why do you feel the rotors need to be turned?

    Just asking.
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  5. no5s

    no5s Terror at 2 mph

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    I tried to surface grind the rotors on my 1150GS. We tried a "dust off" less than .001 with coolant. Both rotors turned into potato chip like shapes. Never seen any metal warp so drasticaly. Had to buy new. I did straighten my VFR rotor with a crescent wrench and an indicator,to get close then a few raps with a wooden dowel and hammer. Good luck.
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  6. Poolside

    Poolside Syndicated

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    What sort of machine was used?<BR><BR>
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  7. no5s

    no5s Terror at 2 mph

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    Large wet surface grinder at our machine shop. Wet table moves under a fixed grinding wheel.
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  8. Poolside

    Poolside Syndicated

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    <BR>A rotary or blanchard grind can make a little difference but, how was the part clamped to the surface grinder table?<BR><BR>
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  9. peterman

    peterman cop magnet

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    magnetic table would be my guess. In that application you would need to do both sides equally and back and forth, to help minimize warping. Brake rotors have tons of stress built up from heating and cooling cycles. When you remove surface material, the stress has to go somewhere, hence the warpage. The same with machining many non-ferrous materials. Just take a thin cut off one side of a flat bar of brass, and watch it curl when you release it!
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  10. Poolside

    Poolside Syndicated

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    Linear grinding creates linear stress on the surface. Sort of 'elastic galling' say. The circular path of a Blanchard stone, and more importantly the rotation of the part under the stone, equalizes that stress.<BR><BR>
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  11. Sal Paradise

    Sal Paradise Dharma Bum

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    I don' think its worth your time. After they are turned the metal will be uneven thickness and because of they're miniscule width they will tend to warp faster.
    #11