Results 1 to 6 of 6

Thread: 74' Disc Brakes

  1. #1
    Registered User godfather's Avatar
    Join Date
    Oct 2006
    Location
    Cadillac, MI area
    Posts
    549

    74' Disc Brakes

    I am looking at purchasing a 74' R90, unknown mileage, very good driver condition.
    I am concerned about the disc brake though. The owner said the master cylinder has been rebuilt. The front brake does not stop the bike like I believe a disc brake should. It feels like an old drum brake. No modulation, no grab, just a hard wood like feel to the brake lever. I cannot get it to lock the front wheel up no matter how hard I try.

    What is the collective consensus about this? I am not opposed to rebuilding or replacing the master cylinder and or caliper if need be, I just would like to know if this brake is normal or should the disc brake be more like the modern day disc brakes? ...yes I know this is a 1974 single disc and will not be like a 2013 system.

    Thank you in advance.
    Attitude is everything!
    1978 R100/7
    08' V-Strom 650 great light weight tourer

  2. #2
    Administrator 20774's Avatar
    Join Date
    Sep 2005
    Location
    San Antonio, TX
    Posts
    13,356
    The ATE caliper and pad probably need to be adjusted for maximum contact. The solid disk for the '74s was not the best...the drilled rotors from '75 were better plus helped with wet conditions. You could consider other changes such as non OEM pads, steel brake line, and a handlebar master cylinder. These types of changes have been noted by others in the past to improve the braking. A more radical approach would be to convert to dual disks which requires buying the slider, changes to the master cylinder (maybe), and the second rotor.
    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
    Join Date
    Dec 2006
    Location
    Houston, TX or Portland, OR
    Posts
    348
    I'd guess it is normal for that bike... the single disc on my /7 was the same way. I tried a number of different pads, careful adjustment of the caliper, and a new rotor, but could not get satisfactory results. I've heard that the single disc ATE was referred to as the original BMW antilock brake system. I finally gave up and converted it to dual disc with floating rotors, which I am very happy with and would do again... but it's not a cheap fix.
    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
    Cal
    Join Date
    Nov 2003
    Location
    Suches, Ga
    Posts
    106
    There is no comparison to a modern brake system. A 1974 front brake is slightly better (maybe) than drum brakes. Make sure it is set up properly and maybe invest in a SS braided brake line.
    Cal Garcia
    Suches, GA

  5. #5
    P Monk
    Join Date
    May 2005
    Location
    Port Neches, Texas
    Posts
    659

    improving braking

    I replaced my original rotor with an ebc one. Replaced pads with ferodo sintered pads and adjusted the front caliper. Now ebc makes a sintered pad to fit the airhead, but not the HH pads I wanted. After they wore in they work ok. Not great but much better than when I bought it. I am probably going to replace the under the tank master cylinder with a handlebar mounted one. There was some posting on boxerworks on how to do that little project. According to the aussie that did that conversion it made significant improvement.
    P. Monk
    74 R90/6 (also know by bride as the Black Hole). 09 R1200 GS. My wife, 1953 model who has survived aplastic anemia and a bone marrow transplant.

  6. #6
    Registered User godfather's Avatar
    Join Date
    Oct 2006
    Location
    Cadillac, MI area
    Posts
    549
    Thanks folks...this is great information. Now I know there is hope for the front brake on this bike.
    Attitude is everything!
    1978 R100/7
    08' V-Strom 650 great light weight tourer

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •