BMW R100GS & R100, bolt on Brembo 4 Piston Caliper Upgrade

Discussion in 'Vendors' started by One Less Harley, Oct 10, 2010.

  1. bpw

    bpw Been here awhile

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    I will want one with pads when they are ready, subscribing to the thread, or PM when you have one to sell.
  2. mbw

    mbw n00b

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    I'm a little late to this thread...What is the status on availability (for a '93 GS)? Looks like a great upgrade! I'm definitely in if there's a waiting list, too. Thanks
  3. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    four done and ready today (edit one sold)...so some should be ready by the end of the day. shipping to Germany is expensive.
  4. mbw

    mbw n00b

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    Thanks for the quick reply. A friend of mine from Nashville is coming over in a few weeks, so I'll ask you to send it to him. Hate to sound rude, but it looks like there are some calipers a little more beat up than others. The nice clean, shiny ones look especially nice. If there's a nice looking one, I'll take it! I'll Paypal or I'll have a paper check go out tomorrow from a Schwab account. I'd like the full package (calipers+EBC+braided+ fitting). Just let me know specifics. MW
  5. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    I've got three on hand, I selected the best of the three and put the best looking allen bolts I have in it. Check your PM' thanks.
  6. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    9/16/2019 make that two on hand
  7. bpw

    bpw Been here awhile

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    Took the first ride with the new caliper, very nice, easy upgrade. Brakes have gone from total crap to pretty reasonable and adequate for street riding. Nothing like a set of twin disc 6 piston sport bike brakes, but a GS front tire couldn't handle that anyways. I would say totally worth doing and makes the GS a lot more rideable in modern traffic.

    One less Harley is a good guy to deal with, mine had a very small machining error and he immediately said said it back so he could fix it. I was able to sort it with a file and 15 minutes of time so didn't bother, but its nice when someone stands behind there work without question.

    All in all, highly recommended, both the caliper upgrade and dealing with One Less Harley.
    windypoint likes this.
  8. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    Hey thanks for taking time to write up a review I do appreciate it. I no longer have a R100GS front end on the G/S, but still glad to make these. I like being able to offer the brake upgrade for these old bikes. It's good to know there are so many enthusiast out there. i can't see ever going to a newer bike when the old airhead does what I need and fits my limited skill set so well.
  9. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    10/26/2019, one caliper left, one set of pads
  10. Reggie Perrin

    Reggie Perrin Airhead Connoisseur

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    Hi, "One Less Harley" and anyone else who has experienced the same as me, and solved it!! I came across your thread having experienced no small amount of frustration mounting one of these upgrade kits to my R80GS (1987).

    Actually I inherited the caliper when I bought the forks from a 1992 R80GS, and didn't immediately twig that the caliper wasn't a standard GS Brembo.

    Having realised this, I bought a new piston and gasket kit, and cleaned it all up. I did split the caliper and installed a new o-ring between the two. Before re-assembling the caliper I really worked at getting the two faces ultra-fine linished perfect, and dressed them with a small amount of silicon grease.

    I then installed new pads, new brake line, new master cylinder. Milled 2mm off the lugs to get it to align with the disc.

    The problem is that I cannot get it to bleed properly, or at least I cannot get the brake to harden up to function anything more than 50% braking.

    I wondered if you had any tips as to what, if anything, I'm doing wrong!!

    My master cylinder is 13mm. Is that too small? Is there air in the caliper that I cannot get to bleed out? BTW I've passed at least 6 cans of brake fluid through to try to get it clear. I've tried taking the caliper off its support and hanging it at different angles to see if there is air trapped. I've also tried swapping the fluid supply and bleed nipple around! I assume by your photos, the bleed nipple should be on the inside.

    Any advice gratefully received!!
  11. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    Reggie-copied from the 1st post

    Bleeding Notes-

    Three helpful hints on bleeding, after having bled in the traditional way, 1) it is seems to help if the caliper bolts are loosened and the bleeder rotated up to the 12 o’clock position during bleeding. 2) Tapping caliper with a rubber hammer or block of wood to free bubbles from the inner cavities. 3) Once final bleed has occurred pump up lever and zip tie lever back over night.
  12. Reggie Perrin

    Reggie Perrin Airhead Connoisseur

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    Thanks very much for the reply. I'll try these suggestions. I'm still finding my way around the site, and reading other posters who have made the modification successfully. IMG_3295.jpg IMG_3295.jpg IMG_3296.jpg

    I did note that there is some discussion about the size of master cylinder to use. I have a 13mm, and wondered if enlarging to a 14 or 15mm has been beneficial to anyone who has made this conversion?

    Also which way round to put the fluid supply and bleed nipple. I've tried both ways in an attempt to bleed it, and it doesn't seem to make any difference.

    Attached Files:

  13. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    12mm provides the best feel and quicker lock up, but a little more lever travel. The stock 13mm is also good, but the larger the bore the less feel and more wooden the braking becomes.

    Stay away from the 14mm and larger, the feel isn't as good.

    You need to work on better bleeding ..just a few bubbles will soften the lever and increase travel.
  14. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    bleed nipple to outside for easier access. make no difference in performance.
  15. Reggie Perrin

    Reggie Perrin Airhead Connoisseur

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    Thanks for the advice my friend.

    I have a standard 13mm master cylinder.

    I have been tapping away with a rubber mallet and pulling bubbles of air out of it for more than an hour. Several cans of brake fluid passed through. It just keeps coming. I am using a vacuum flask on a compressor.

    I've tried the bleed nipple at 12 o-clock, and back in the correct position. I can only seem to get the brake to tighten up to about 60% of what I would assume it to be.

    No evidence of any fluid leaking, it has crossed my mind that the caliper isn't sealed properly hence the air.

    I've left it overnight zip tied tight to the grip, and will see later if it's made any difference.

    I wonder if you have ever tried making a second bleed nipple on the inside half of the caliper? As I am pretty sure the air is in the inside part.

    I'll keep persevering!!! But most frustrating.
  16. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    you could always try back bleeding with a syringe at the bleeder...sounds like you've got some air in there though.

    did you make sure you put the seals in the correct locations, the seals are so close to the same size...did the pistons go back in with ease?? if not you might have cut a seal pushing the pistons back in.
  17. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    did you get a new o-ring as I didn't think it came in the kit.....I use over sized o-rings for better sealing.


    I snug up the middle bolts on the caliper 1st, loosely install the longer outer two.

    then back to the short inner bolts, tightening the one closer to the o-ring 1st. then the the other.

    (note- You have a long and short bolt with the o-ring between,, that's where the caliper seals between the halves, so I favor tightening that 1st. If you tighten the outer ones it pulls the caliper haves kind of apart)

    on the longer bolts, snug up, then tighten the one closest to the o-ring. the the one furthest.


    If you tighten the long bolts 1st it will not seal as well. Especially with the standard sized o-ring....I'm not saying this is your problem though..sounds like air in the lines to me..
  18. Reggie Perrin

    Reggie Perrin Airhead Connoisseur

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  19. Reggie Perrin

    Reggie Perrin Airhead Connoisseur

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    Hi, thanks for your help. I've been at this again all afternoon, very frustrating! I'm still not there.

    1. Yes I got a new o-ring with the kit, its a special size. Seems to fit snug in the recess, but I wouldn't say its over-size. MAYBE, maybe that is the problem.

    2. I actually stripped the caliper again this afternoon and started again. Checked all chambers and pathways. Filled the piston recesses with brake fluid before re-installing. All pistons moving smoothly.

    3. Yes I followed a similar tightening technique to you, gradually tightening them all up. Then installing the caliper on the lugs and doing the final tighten in position. Do you dress the inner faces of the caliper with any sealant or oil?

    4. I did want to ask you if the piston seals are square or tapered on these callipers. I forgot to check, and did wonder if that might be the problem...

    5. This time I removed the caliper from the disc and wedged open the pads, which meant that the pistons were in full retreat position. I then bled the system and once achieved, put the pressure back on while topping up the master cylinder.

    6. I use a vacuum chamber running off my compressor.

    After many many runs, I never quite get to full brake firmness. No bubbles coming through, and I have now tied off the brake lever fully compressed and will let it sit for a few days.

    I have an R100GS with standard caliper and I compare the feel of the brake to that. It's nowhere near as good! And I was hoping this would be better... IMG_3313.jpg 7f7618ee-da52-4b3e-85d1-a12c6d2d6f2b.JPG IMG_3297.jpg IMG_3315.jpg IMG_3313.jpg IMG_3315.jpg
  20. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    I don't use pressure...not needed just gravity feed with pumping the lever. No need to dress the faces, but you do need to put brake fluid on your finger and wet the seals and o-ring