So you want better brake on your R100GS, why not a 4-pot Brembo????

Discussion in 'Airheads' started by One Less Harley, Oct 1, 2010.

  1. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    So you want better brakes on your R100GS??? Why not try something already available from BMW????​



    Like one of these calipers….​



    [​IMG]



    The mounting tab spacing of the R100GS caliper is the same as the left 4 pot Brembo from a R1100xx, K1100xx, R1200C or an early R1150GS (up to 11/2001). I can’t take credit for finding out that this works as there are a few references posted here on ADV Rider about the conversion. The only modification needed is to remove 0.158” off the caliper mounting tabs. This keeps the rotor centered to the caliper. I double checked the measurement and came within a few thousandths of and inch….good enough.​





    One thing that concerned me, was milling that much material would make the tabs too thin.​



    The stock 2 pot Brembo is 0.489” thick



    [​IMG]


    The left 4 pot Brembo before milling tabs ( 0.609")



    [​IMG]


    Area of material removed (0.158")


    [​IMG]


    Thickness of tab after milling (0.451")


    [​IMG]





    With 0.158" milled off the mounting tabs, the 4 pot Brembo is 0.038" thinner than the stock 2 pot Brembo.


    I have 6 calipers, but only one has been modified. I need to double check the fit and centering of caliper to the rotor before having the other five milled. ​

    I have a friend w/ a R100GS who is interested in trying the 4 pot caliper, but I'm waiting on an order of Galfer green pads to arrive. So look for more postings once it is installed. The bike will also (if he wants to spend the money) get a stainless line.
    The five other calipers will be offered here with Galfer green pads and stainless lines.​
    #1
  2. fishkens

    fishkens Long timer

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    I'd love one of those fancy calipers since I probably won't be affording the billet unit anytime soon. Price?

    Thanks.
    #2
  3. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    I don't know as of yet. I need to make sure the 1st caliper is machined correctly. Then need to get all the pads and stainless lines in, plus see what the total machining cost will be. The machinist is quite reasonable though.
    #3
  4. fishkens

    fishkens Long timer

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    Ahh, so this'll be a turnkey solution. Nice. Keep us posted.

    I haven't done a search but is there a preferred pad?
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  5. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    I've read ( for what that's worth) the Galfer Green offers good braking. I'll post when converting my friends R100GSPD. I've never ridden a 2 pot Brembo on the GS. So I'll be relying on his impressions.
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  6. fishkens

    fishkens Long timer

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  7. bereahorn

    bereahorn Long timer

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    I made this mod to my '92GSPD and like the result. I think my caliper is from an R1100R and a friend milled the required amount from the caliper to center it over the disc. I think it's an effective and worthwhile mod. The stopping is much better. Of course the addition of a racetech gold valve contributed also.
    #7
  8. fishkens

    fishkens Long timer

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    Okay, so now I'm thinking. Does it really need to be milled to be centered over the rotor? I mean, do the pistons really care if the guys on the one side of the are a little bit deeper in their bores and the fellows on the other side are a little bit prouder in their bores? We're talking about 1/16th of an inch on each side.

    Hmmmm, just how much do the pistons care if they're all in the same relative position in the bores?

    Am I misisng something?
    #8
  9. espressodrinker

    espressodrinker Cape Town Wanderer

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    The pressure in a hydraulic system HAS to be the same all over the piping.

    I agree I can't see what diffs it would make for the disk to be off-centre.
    #9
  10. B.Curvin

    B.Curvin Feral Chia tamer

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    :huh

    For future reference, there are no stupid questions, but there are stupid answers.

    Did you just make that up as you typed?





    Yeppers.
    #10
  11. C Squared

    C Squared Now with TURBO!

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    For future reference, there are no stupid questions, but there are stupid answers.

    Did you just make that up as you typed?



    Hey you syole my reply. I just wanted to know how the pressure would be greater in one side over the other? I'd love to read the rational. Maybe there is a new field of physics that I am un aware of?
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  12. B.Curvin

    B.Curvin Feral Chia tamer

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    I saw I had been quoted and thought for sure someone was going to bash me for being an asshole. :lol3
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  13. ipanemaguy

    ipanemaguy Many bikes & little time

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    Quite correctly several have stated that in a hydraulic system the pressure equalizes, hence the inner and outer pistons will have the same pressure if they are driven from the same master.
    I will suggest that the problem arises at some off-center differential that the pads on one side may retract insufficiently to completely clear the rotor and result in brake drag, overheating (and consequent warping) of the rotor.
    Some difference may be OK, too much is harmful - as is everything else in life.
    #13
  14. One Less Harley

    One Less Harley OH.THAT'S GONNA HURT

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    I doubt you could get the pad in the caliper on one side.
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  15. Christos 1983

    Christos 1983 Adventurer

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    i am an owner of a bmw r100gs p-d.i have change the standard calliper with a 4-piston nissin from gsxr 750,i have put metal brake lines and a brake disk from cbr 900.now i have stronger brake but i have more 'travel 'in the brake lever...i want to change the master cylinder to reduce the 'travel' and make the brake feeling more instant.From what bike can i put?the master cylinder from a 1100-1150 is suitable?
    thanx guys!

    sorry about my english but i am from greece and i have not practised them for a long time....
    #15
  16. x3300

    x3300 geoff

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    Just for anyone interested, pressure in hydraulic systems was explaned by Bernoulli:

    -x3300
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  17. bikecat

    bikecat Long timer

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    Made the mod to my K75. Used the same master cylinder. Shimmed down the caliper and enjoy much better braking power. The key is the mounting points; they are similar, I think 65mm eye to eye if I recall correctly.

    Can post pics if anyone is keen.

    Christos, I think you are better off playing with spacers, springs and oil than changing a master cylinder. Nothing wrong with your English! :)

    Cheers
    #17
  18. Christos 1983

    Christos 1983 Adventurer

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    bikecat i have read threads you have started and i have seen that you are an owner of a r100gs '88.
    i have made the following modifications:
    1.front usd wp forks from ktm lc4,top yoke from suzuki rm 125/250,lower yoke from ktm lc4 too.ihave made spacers to fit gsxr's caliper.I have left the standard bmw wheel rim and axle.
    2.rear shock ohlins
    3.renthal fat-bar
    With the ohlins and the usd wp i have enormous better handling.But the brake feeling is something i want to upgrade.

    i am concerning about my english because i live in Greece and first time i write at a universal forum.
    #18
  19. Toyanvil

    Toyanvil Adventurer

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    You guys got me thinking, for some reason my front wheel is dished to the right side 5 mm. I was thinking, I could install the Brembo caliper and change the wheel spacers. This would center my wheel and the caliper would bolt right up, right?
    [​IMG]
    #19
  20. fishkens

    fishkens Long timer

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    Thanks for the links.

    So, centering the caliper perfectly over the disc is not needed to equalize pressure but, depending on the depth of the cylinders and other clearances of the caliper relative to the disc, spokes, etc., it may be needed to allow new pads to be fitted or to keep the disc, spokes, etc. from rubbing on the caliper.

    That's what I was thinking but I was interested to hear if that thinking was correct.
    #20