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Thread: '78 R100/7 front brake worth saving?

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  1. #1
    Registered User vintagethumper's Avatar
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    '78 R100/7 front brake worth saving?

    I'm going through the mechanical bits on the '78/7 that I'm reviving from a long storage. It only has about 11K miles, so much of it is still good, but the front brake is terrible. The lever pressure required to slow it down is excessive and it has an overall wooden feel. The pads have worn at odd angles (wedge shapes), so maybe it had been run with the eccentric adjuster incorrectly set? My question is; Is it worth putting money into this system, such as pads, brake lines, possible caliper rebuild etc.? Or would my money be better spent toward a newer style front brake? I just don't know if the OEM brake has the potential to work well if everything is in good order.

  2. #2
    Liaison 20774's Avatar
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    I personally like the single ATE on my /7. I don't have much other experience...my other two bikes are drums. As for the wedge shaped pads, they actually come that way. I remember seeing that the first time and thought they were badly worn. Then I looked at the new pads.

    It's probably worth it to give it a go to rebuild your existing system. I ended up using bits of what Brook posted in one of his rebuild series...probably the '77 R100RS. You may find some pitting in the walls of the master cylinder which you will need to deal with. If not too bad, Brook shows how to chuck up some sandpaper on a dowel into a drill and buff things out. If the pitting is too far gone, then it becomes more problematic and costly where a switch to the handlebar setup may be wise. The only issue will be finding a master cylinder size that works as I believe the sizes are not identical so some choices will have to be made.
    Kurt -- Forum Liaison ---> 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
    Depends on what you intend to do with it and where. If you want to ride it regularly and you live anywhere near an urban area I would upgrade the system. Your best bet would be the front end off a later R100 with double discs. I recall my '84 with steel brake lines being pretty good -- IIRC it had calipers that did not use eccentrics. That upgrade would be pricey. You can get a lot of improvement with a steel brake line, EBC pads and proper adjustment of the eccentric. And I imagine and accessory disc might also improve performance. At minimum I would replace the seals in the MC and caliper. I found replacing the piston in a ATE caliper very difficult. Get some red rubber grease if you do this.
    '61 Clubman's Gold Star, '13 690 Duke, '13 Daytona 675R, '18 Street Triple RS, 2020 R1250R (gone but not forgotten: '76 R75/6, '84 R100, '76 R90S)

  4. #4
    Rally Rat 1074's Avatar
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    Front brake

    I like the idea of going to an aftermarket rotor and pads along with a braided ss line. My preference is EBC or Ferodo. You might want to replace the cable as well. Most cost effective use of your money.
    Boxerbruce

  5. #5
    Registered User vintagethumper's Avatar
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    This is all very helpful. Iím ok with vintage brakes, so long as theyĎre good ones. But my commute is a twisty road through the hills (near Laguna Seca) and there are deer around. In its current state, this front brake is unacceptable. If I can repair it so itís a 2-finger brake, rather than the current 4-finger brake, Iíll be good to go, er, stop.

  6. #6
    Quote Originally Posted by vintagethumper View Post
    This is all very helpful. Iím ok with vintage brakes, so long as theyĎre good ones. But my commute is a twisty road through the hills (near Laguna Seca) and there are deer around. In its current state, this front brake is unacceptable. If I can repair it so itís a 2-finger brake, rather than the current 4-finger brake, Iíll be good to go, er, stop.
    The single disk ATE setup was BMW's original ABS. Dual disk was adequate.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  7. #7
    I have a 77 R100RS (a /7 with dual front disk brakes). In the process of going through this bike I fully disassembled the front forks (new seals and progressive springs), wheel (stainless spokes, painted rim, new bearings, shimmed, fresh rubber), brakes, and the rest of the bike.

    The ATE brakes were disassembled, cleaned, repainted, and new seals, brake pads, and brake hoses installed. Brake hoses were from Spiegler. The under tank master cylinder was re-built (new seals and spring - was in a kit from Re-Psycle BMW). The eccentric adjuster was
    cleaned and lubricated. The rotor was ok (not warped and thickness was in spec). I adjusted the eccentric adjuster so that the new pads made uniform contact with the brake rotor. As I recall I used a magic marker and worked to get the black marker line cleanly erased. Once the new
    pads were properly adjusted the brakes work quite well.

  8. #8
    Quote Originally Posted by vintagethumper View Post
    This is all very helpful. Iím ok with vintage brakes, so long as theyĎre good ones. But my commute is a twisty road through the hills (near Laguna Seca) and there are deer around. In its current state, this front brake is unacceptable. If I can repair it so itís a 2-finger brake, rather than the current 4-finger brake, Iíll be good to go, er, stop.
    In that case, I would also go with a handlebar mounted MC.
    '61 Clubman's Gold Star, '13 690 Duke, '13 Daytona 675R, '18 Street Triple RS, 2020 R1250R (gone but not forgotten: '76 R75/6, '84 R100, '76 R90S)

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