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Thread: Front brake binding on '76 R90/6

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  1. #1
    Registered User ezwicky's Avatar
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    Front brake binding on '76 R90/6

    howdy all,

    i have a new-to-me '76 R90/6 and the front wheel is difficult to roll because the brake is sticking or binding.

    i tried adjusting the cam pin in the caliper and that helped a little but it's still not right. sometimes it's hard to turn the front wheel, sometimes it's almost impossible. there's no free play in the hand lever, no sponginess.

    i think i am looking at a caliper rebuild, what do you all think? this was a tampa-area bike and maybe the salt air has hastened corrosion?

    a rebuild kit is about $120 and i am wondering if i should also just go ahead and rebuild the master cylinder as well for another $75 or so?

    thanks in advance for any advice.

    -eric
    BMWMOA #182796

    '76 R90/6

  2. #2
    Administrator 20774's Avatar
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    Your rebuild kit probably includes a new piston. IIRC kits can be found for cheaper w/o the piston.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
    Registered User jad01's Avatar
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    Quote Originally Posted by 20774 View Post
    Your rebuild kit probably includes a new piston. IIRC kits can be found for cheaper w/o the piston.
    When I rebuilt mine as I was doing my dual disc conversion, I found one piston was rust-pitted pretty badly, and one was OK... If you proceed with a caliper rebuild, I would recommend disassembling the caliper before you order the parts so that you will know which kit you need (w/ piston or not).
    Jim
    '78 R80/7 and '84 R100RS (Blues Brothers), '86 K75C (Icy Hot)
    '90 and '93 Mazda Miatas (Jelly Bean and Red Hot), '02 325ci (Blue Streak)
    '96 Giant Upland (big Kendas & freshly greased bearings!)

  4. #4
    #4869 DennisDarrow's Avatar
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    Have you tried to change out the brake fluid?......This needs to be done at least every couple of years........Have you adjusted the brake cable at the master cylinder?.....The "tool" to do this is part of your tool kit with the feeler guages. For me, I would do a flush and adjust of the system before tearing it apart.

    Has this just begun to do this or did you get the bike in this condition? Could very well be lousy maintenance by the previous owner and just needs cleaning and adjusting............God bless.......Dennis

  5. #5
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    There should be some free play in the hand lever, ~1-2mm IIRC. The cable adjustment is at the master cylinder though, which requires the tank be removed for access. Before tearing the caliper apart, I would do a fluid flush once or twice, spray brake parts cleaner on the pads while turning the wheel, and adjust the cable for some free play at the hand lever. The fluid flush can be done at the same time the cable is adjusted because the tank must be removed for both.

    I found attaching a small length of clear PVC tubing on the bleed nipple allows gravity draining brake fluid with minimal mess. A timer or some other reminder is needed so you don't forget to check the master cylinder while fluid is dripping out the caliper and run out of fluid. Otherwise, a mechanical pump/syringe can be used to extract the brake fluid. If the brakes are not permanently locked, fresh fluid and cleaning the pads/piston seals with spray brake cleaner may be all that is required. I had a similar situation with my single rotor ATE caliper and that fixed the problem. Good luck!
    Stan

    AH# 13238

  6. #6
    Registered User ezwicky's Avatar
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    this is a great forum! thanks for all the advice, and i will start in as soon as possible. barron williams also gave me similar advice.

    will break out the clymer's and get to work. i'll keep you all posted.

    thanks everybody,

    -eric
    BMWMOA #182796

    '76 R90/6

  7. #7
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    Same issue with K1200LT

    I had this same problem with my 2000 K1200LT. I live in Newfoundland and when I took the bike to the dealer, they found that the guide pins the shoes slide on were corroded (presumably from the salt air). Since the calipers on the bike have inner stainless components, a rebuild was unnecessary. These pins were replaced, brakes bled and no more issues. Breaks felt like new. My clue was spraying them with silicon freed them up (but had a negative impact on breaking). Hope this helps.

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