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Thread: 1980 R100 front brake free play

  1. #16
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    Jad01

    I am not sure about the calipers, at the moment. I assume they are stock as the bike only has 24,000 miles. They are single caliper though. Maybe a rebuild is in order but it seems early to consider. I have 4 mm with the feral against the mc fork. I think the goal is 8-12.

  2. #17
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    Jad01

    I thought I replied to the thread but it may be in space. I have a single puck caliper. I assume they are stock. The bike only has 24,000 miles so it hard to think a rebuild would be in order. I have 4 mm of free play with the feral against the mc fork. I think the target is 8-12.

  3. #18
    Registered User lmo1131's Avatar
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    can you post some pics? I'd say free-play, is free-play...
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

  4. #19
    Registered User jad01's Avatar
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    Quote Originally Posted by lmc3881 View Post
    I am not sure about the calipers, at the moment. I assume they are stock as the bike only has 24,000 miles. They are single caliper though. Maybe a rebuild is in order but it seems early to consider. I have 4 mm with the feral against the mc fork. I think the goal is 8-12.
    My sense is that there are somewhat limited options for free play in this system (based on my experience with my undertank set-up). If you use the feeler gauge method that Lew references, the free play is pretty much constant, and would only change as the cable stretches over time (thus increasing play). My bike only has the adjuster at the master cylinder as Barron suggests- no adjustment at the handlebar lever.

    It sounds like you have the ATE caliper (not the Brembo caliper). As Barron suggests, adjusting the caliper via the eccentric bolt is important to the performance of the brakes- if you have had the caliper out and did not properly adjust it when you reinstalled it, that could explain the lack of freeplay as the pads may no longer be parallel to the rotor. Otherwise, there is likely something at issue in the hydraulics. The ATE calipers are the most likely culprit in my experience (limited as it is). They are aluminum with a steel piston. The calipers are very prone to corrosion if the brake fluid is not changed frequently (annually). This is not a mileage issue, but rather one of time. As the internal surface of the piston and caliper bore corrode, and the rubber seal on the piston hardens, the piston does not retract as much in the bore when the lever is released and pressure relieved. While you may not be noting excessive drag at the rotor (the ATE will likely have a little under even the best circumstances), this may explain why the lever free travel is not what you expect.

    You could try to flush the brake fluid and see if that helps, but you will likely be amazed at the difference new seals (and a piston, since it comes with the kit) will make.

    Good luck!

    PS: Lew is right- pics would help!
    Last edited by jad01; 03-25-2013 at 03:13 PM.
    Jim
    '78 R80/7 and '84 R100RS (Blues Brothers)
    '90 and '93 Red Mazda Miatas ("Jelly Bean" and "Red Hot")
    '96 Giant Upland (big Kendas & freshly greased bearings!)

  5. #20
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    Jad01

    I think I will just rebuild the calipers and get back to the thread with results. It's the only thing that make sense.
    When I first adjusted the calipers/pads, I used a feeler gauge to get the front/back position the same. However, the wheels would not release after applying the brake. (That should have been a clue) Having not done this before, I wasn't sure what to expect. Then after checking everything else, I adjusted the calipers/pads so the wheel was free, disregarding the parallel requirement. That freed the wheel, but didn't really affect the free play. More to come. Again, thanks to all for the input.

  6. #21
    Registered User lmo1131's Avatar
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    For what it's worth... I thought that I had one of these in my ditty box. I found it this morning.

    All I have is the brake gauge, but if you'd like it it's yours, just PM me with your information and I'll drop it in the mail.
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    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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