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Brake problems

Discussion in 'Maintenance and Servicing' started by snuff3r, Dec 18, 2014.

  1. Hi,

    New to servicing brakes (only ever done pads) but would like some advice as I am not sure what the problem is..

    I picked up a second hand 2002 R1 after my Daytona was stolen a few months back. It's a nice ride, very diff to the Daytona. I'm cleaning up some small items on it relating to vibration and cooling but i have a brake problem and am not sure where to start diagnosing it.

    If i apply front brakes.. it'll get to a point where it's lightly braking.. then it's quite tight. At this point i have to apply quite an amount of pressure. It then jumps.. almost ratchets, to a point where it's braking heavily. Ie, it's not smooth application.. Does this make sense?

    I assume the pistons need greasing or have dirt in them. Am i heading in the right direction? Would like some ideas before i pull it apart.


  2. Sounds pretty scary. I would take caliper off and see if it's sliding in and out properly. Might be gummed up and need a good clean and some grease.
    • Agree Agree x 1
  3. I'm pretty paranoid about motorcycling (bought an R1, go figure, hah!) but it's not massively bad, feathering the rears evens it out quite a bit. But i'd love to get them back to scratch.

    Feels like the pistons are sticking so i assume they're dirty, hopefully not damaged. Just wanted to get some ideas before i pulled them apart and can't put them back together.
  4. It may just be the slides on the calipers not the actual pistons. If your bikes brakes are the same as the ones I have worked on if u know what I mean. The slides usually have little rubber dust boots over them to keep dust out. If they are broken and dust gets in they could be sticking.
  5. no slides.. R1 calipers are 4 pots up front

    do both discs look equally worn? one more than the other?
  6. Do I need to pull them apart to tell this?

    Ive only ever replaced pads.. and I've not had the r1 for long..
  7. R1 has semi floating discs and radial mounted fixed calipers.
    Check for worn or unevenly worn pads and seized pistons in the calipers. As oldcorollas has pointed out disc rotor wear would point to the caliper with the problem, seized piston(s) = less wear to the rotor.
    To check the rotor thickness, use a vernier or micrometer as your measuring in 1/10's of a millimeter. The rotor will also be stamped with a minimum thickness, which will also be a consideration on whether to replace or machine the rotor if required.
  8. Also check your brake lever pivot bolt. If the lubricant has dried up, it can make the brakes a bit hard to modulate.


    • Agree Agree x 1
  9. All good advice. Thanks all. Ill disassemble it over the break.
  10. If all that doesn't work, try a bit of grease where the lever acts on the master cylinder.

    I had a similar problem on my Z750 - slight ratcheting or seizing feeling in the lever - tried all of the above to no avail and then, on a whim, dabbed a bit of grease on the plunger and hey presto, smooth lever action. The join shouldn't need lube (the plunger pushes more or less straight into the piston) but maybe there was just enough lateral movement between the parts to cause some stickiness.