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

  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. Im ok with vintage brakes, so long as theyre 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 its a 2-finger brake, rather than the current 4-finger brake, Ill be good to go, er, stop.

  6. #6
    Quote Originally Posted by vintagethumper View Post
    This is all very helpful. Im ok with vintage brakes, so long as theyre 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 its a 2-finger brake, rather than the current 4-finger brake, Ill 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
    jimmy armour
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    /7 brakes

    Hi regards the angled brake pads they are like that from new ,and must be adjusted correctly, as per last post ,if they still are not good enough , try to obtain a used 1981 on handle bar mounted master cylinder 13 mm if possible, makes a big difference then if things still arn,t good enough ,again try to get a used twin disc front end or bits to add the extra disc, this is what I have on my 1977 r100 S /rs/rt ,friends say its as good as their brembo twin disc set up, once had to do a stoppie on it as a transport truck locked all its wheels in front of me black smoke and all,at about 45 miles per hour, broke the RS screen with my big belly but stop she did, or go straight to a brembo front end assy and handle bar mounted master cylinder, best of luck ,hope this assists ,Jimmy

  9. #9
    Quote Originally Posted by vintagethumper View Post
    This is all very helpful. Im ok with vintage brakes, so long as theyre 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 its a 2-finger brake, rather than the current 4-finger brake, Ill 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)

  10. #10
    Registered User vintagethumper's Avatar
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    Quote Originally Posted by ccolwell View Post
    In that case, I would also go with a handlebar mounted MC.

    What are you guys using to do this? Is there a BMW handlebar mounted master cylinder with switch assembly and throttle that could replace my current combined brake lever, throttle and switch combo?

  11. #11
    Oak (a now deceased airhead guru) had a good deal to say about this topic. Alas, he would not allow his articles to be made available as electronic files. If you join the ABC (Airheads Beemer Club; a worthwhile thing anyway!) you could obtain Oak's index then order the back issue of Airmail. This might take a while.
    http://www.airheads.org/

    A less difficult path might be to contact Mark at Re-Psycle BMW; he can advise you of your options and might have a good used handlebar unit available.
    https://re-psycle.com/

    You could also try Ted Porter as he knows a good bit about BMW airheads -
    https://www.beemershop.com/

    Tom Cutter knows a lot about airheads: (I understand that he has had some health issues, so I don't know about his availability).
    http://rubberchickenracinggarage.com/

    These fellers have recently relocated to NC and have a number of nice informative videos on YouTube. They may be able to help with obtaining a handlebar master cylinder set-up for a /7
    http://www.boxer2valve.com/

  12. #12
    Quote Originally Posted by vintagethumper View Post
    What are you guys using to do this? Is there a BMW handlebar mounted master cylinder with switch assembly and throttle that could replace my current combined brake lever, throttle and switch combo?
    When I considered it for my R90S I looked at BMW parts. A search on this forum should give you some ideas.
    '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)

  13. #13
    Airhead
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    My 1975 R90/6 has the stock single-disc ATE brake with the fluid reservoir under the tank. Properly set up I find it perfectly adequate, as long as you avoid following cars doing 60mph at 10 feet distance.

    I use EBC FA-22 Kevlar/Non-Asbestos Organic pads. I tell myself they work better than OEM, which is doubtless the placebo effect at work.

    When installing, I draw a pair of radial lines using a Magic Marker on the disc. Two lines at 90 degrees spacing. Then I work the brake and use the eccentric adjuster on the ATE caliper until all of the magic marker lines get rubbed off at the same time. That indicates the pad material is parallel to the disc, meaning maximum braking effect.

    EBC are British made, but don't panic. There is no Joe Lucas content.

    Bob's BMW carries them.

  14. #14
    Registered User VIEJO's Avatar
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    Quote Originally Posted by robsryder View Post
    Oak (a now deceased airhead guru) had a good deal to say about this topic. Alas, he would not allow his articles to be made available as electronic files. If you join the ABC (Airheads Beemer Club; a worthwhile thing anyway!) you could obtain Oak's index then order the back issue of Airmail. This might take a while.
    http://www.airheads.org/

    A less difficult path might be to contact Mark at Re-Psycle BMW; he can advise you of your options and might have a good used handlebar unit available.
    https://re-psycle.com/

    You could also try Ted Porter as he knows a good bit about BMW airheads -
    https://www.beemershop.com/

    Tom Cutter knows a lot about airheads: (I understand that he has had some health issues, so I don't know about his availability).
    http://rubberchickenracinggarage.com/

    These fellers have recently relocated to NC and have a number of nice informative videos on YouTube. They may be able to help with obtaining a handlebar master cylinder set-up for a /7
    http://www.boxer2valve.com/
    If you are interested in going in even deeper regarding front disc brakes on airheads I suggest you check out the user forums on the Airheads Beemer Club website. I'm not sure of the exact forum reference(s) but there is an extended discussion of modifications to brake cylinder bores/slave cylinder bores/cylinder lever-arm lengths/brake pull lever lengths that is very interesting. Several links to "Snowbum" Tech Articles as well as links to facilities that can accomplish most of the mods discussed. Almost everything discussed requires machine work of some sort.

  15. #15
    Snowbum has written extensively about airheads. His section on airhead brakes is below -

    https://bmwmotorcycletech.info/brakes.htm

    About 2/3 of the way down in this part is a section called "Numbered Section". There is discussion about ATE brake conversions.

    I found Snowbum's info difficult to take in at one go. It might be easier to save and/or print a section and read / digest the info
    over a period of time.

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