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Caliper rebuild? Brake Help

Discussion in 'Tech' started by Kyle Brosius, Apr 14, 2018.

  1. Kyle Brosius

    Kyle Brosius Well-Known Member

    I have an 09 GSXR1000 with an RCs19 master cylinder, stainless lines and RJL pads. The brakes are great the lever is nice and firm easy to trail brake ect. This is my street bike so it’s not really necessary to have brakes that good but man is it nice.

    My race bike is an 06 GSXR600 Superbike. I loved the feel of my 1000s brakes so I put the same set up on it. I was trying to save money so I found a deal for a used RCS19 with stainless lines and a set of 09 gsxr1000 calipers. I got some new RJL pads for it and refinished the rotors.

    Problem I’m having is I can’t seem to get the brake lever as firm as the one on my street bike. There is also more travel in my lever before the brakes start to grab than on the 1000. I’ve bled 2 cans of fluid through the brakes and there is no air in them. I’m going to try swapping to another set of brake lines I have sitting around but not convinced that’ll fix the issue. I’m wondering how you know when you need to rebuild your calipers and if this is a symptom of them needing rebuilt? I’m to the point of just swapping the whole brake system from bike to bike.
     
  2. baconologist

    baconologist Well-Known Member

    Sure sounds like theres still air in there.
     
  3. SPL170db

    SPL170db Trackday winner

    Look at the calipers with the pads out, when you squeeze the lever do all pistons move freely and at the same speed? If some are moving while others appear slow or stuck then it’s time to bust them down and give everything a thorough cleaning.
     
    Kyle Brosius likes this.
  4. Kyle Brosius

    Kyle Brosius Well-Known Member

    Thanks I’m going to check that out, it doesn’t seem like that would cause my problem though. I am leaning toward the master cylinder needing rebuilt but at that point I might as well just buy a new one.
     
  5. SPL170db

    SPL170db Trackday winner

    Well it depends, if that is the issue then 1 or 2 pistons could hit the pads first while the remaining haven’t caught up, so it feels like less pressure at the lever.

    It is a possibility that the used MC you bought is wearing out, I’m guessing they didn’t tell you how much or what kind of mileage was on it. FYI, the RCS if I remember correctly isn’t designed to be easily rebuilt, they have to be shipped back to Italy for that. :-/

    Either way it’s worth checking and it’s quick and easy enough to do.
     
    Kyle Brosius likes this.
  6. Kyle Brosius

    Kyle Brosius Well-Known Member

    That’s what it feels like but I’ve done every trick I know of to get the air out and there are no bubbles when bleeding. I’ve even hooked a vacuum bleeder to it. I wish I had the right attachment for my pressure bleeder because I would give that a try.
     
  7. Kyle Brosius

    Kyle Brosius Well-Known Member

    Yeah I’ll take a look at them. Yeah I’d have to ship it to yoyodyne then have them ship it to Italy pay to get it rebuilt then ship it back. I’m assuming between the cost and downtime I should just get a new one at that point.
     
  8. badmoon692008

    badmoon692008 Well-Known Member

    I know I had a buddy who bought a used brembo master that he bought and spent ages trying to bleed it and could never get it to work right. Turns out it was crashed and repaired but something must have been just slightly tweaked... He bought a new one and it worked great as soon as he installed it. Hope you have a cheaper outcome than that.

    I'd say if you have the time/inkling maybe try swapping the master from your 1000 to the 600... If it immediately makes things better then you have your culprit.
     
    Kyle Brosius likes this.
  9. Kyle Brosius

    Kyle Brosius Well-Known Member

    I may try that I was considering swapping the entire braking system over. Swapping the master cylinder may be smarter though.
     
    badmoon692008 likes this.
  10. Dave675

    Dave675 Well-Known Member

    If you are going to get rid of that rcs and want to stick with brembo, I would look for the mk2 models. Thats probably the best bang for the buck master cylinder out there.
     
    neckbrace likes this.
  11. Xiyang Liu

    Xiyang Liu Well-Known Member

    Did you ever figure out what the problem was? Any solution?
     
  12. Kyle Brosius

    Kyle Brosius Well-Known Member

    After two sets of calipers I still couldn’t get it as good as my street bike. I swapped to r6 calipers and life has been good ever since!
     
  13. Xiyang Liu

    Xiyang Liu Well-Known Member

    Yea monoblock is probably inherently better, less flex. What size piston MC were u using? 17?19? I been wanting to switch to 09-10 gsxr1000 monoblocks, I heard they were great upgrades also, and direct bolt on, slightly smaller caliper pistons, but not as small as R6.


    Sent from my iPhone using Tapatalk
     
  14. Kyle Brosius

    Kyle Brosius Well-Known Member

    I was using an rcs19 and wound up with a rcs19 corsa corta with r6 calipers. I have that setup now on all three of my GSXR600 race bikes and prefer it to the tokico gsxr1000 calipers. With the adjustability of the master cylinder it is easy to tune the brake feel to your liking.
     
  15. DBConz

    DBConz Registered Idiot

    my GSXR gets new calipers and seals every year
     
  16. Xiyang Liu

    Xiyang Liu Well-Known Member

    Wait wut?! New caliper every year?


    Sent from my iPhone using Tapatalk
     
    DmanSlam likes this.
  17. Xiyang Liu

    Xiyang Liu Well-Known Member

    I’m using Accossato 19*18, so no adjustability there. I’m thinking rebuilding my calipers with new seals. I heard sometimes under-lubricated seal will cause too much piston retractions, which may be the reason why I got too much “free play” before getting pressure at lever. If that doesn’t work, maybe a replacement caliper is the next step.


    Sent from my iPhone using Tapatalk
     
  18. DBConz

    DBConz Registered Idiot

    pistons and seals every year. sorry.

    i clean my pistons every other race weekend, and replace the seals & pistons every year.
    the GSXR calipers are terrible, except 09 & 11 GSXR1000. the 06-09 tokiko's and brembos from 11+ are crap.
     
  19. Xiyang Liu

    Xiyang Liu Well-Known Member

    That is what I heard also. Right now between the R6 and 09GSXR1000 calipers, I'm more towards the latter, because it's direct bolt on, same pads, same brake line, and no potential need for 17RCS.

    I assume u r using the 09GSXR1000 calipers. From my research, I know they are slightly smaller piston sizes than the 600 tokikos, and might cause less travel and less feel in the lever. Is that why you consider it better? Or is it because monoblocks r more consistent?
     
  20. DBConz

    DBConz Registered Idiot

    i'm still using 06 600 split calipers. if i had 09/11 GSXR1000 calipers, i'd probably only have to replace the seals yearly and not also the pistons.
    the 09/11 calipers are a direct bolt-on for the 06-09 600/750's and use the same brake pads as well. yes the pistons are a different size. R6 calipers require spacers to fit.
     

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