rear brake

Discussion in 'Canadian Daves JustKDX' started by longtime coming, Jan 10, 2009.

  1. longtime coming

    longtime coming Rookie DRN Member

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    I find that my '05 kdx 220's rear brake is basically an on/off switch. I'm tired of it. I'm guessing different pads could cure this. Or? Does anyone find the same and how did you fix it. The front brake is fine.


  2. Zach10122791

    Zach10122791 Rookie DRN Member

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    it's the pads i bought the cheap tusk pads from rocky mountain and if my foots not down hard and locking the back wheel up then i basically can't stop or slow down,it pisses me off but i got used to it.
  3. longtime coming

    longtime coming Rookie DRN Member

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    Ok, maybe I'll re-phrase that. What brake pad would make the rear brake on an '05 kdx220 more progressive. It has, since new, always been poor. Lots of power. No feel. Or am I the only one who feels this way about this stock set-up?

    thanks
  4. longtime coming

    longtime coming Rookie DRN Member

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    Do you guys like your stock rear brakes?!
  5. sr5bidder

    sr5bidder Rookie DRN Member

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    Hey longtime try introducing some air into the caliper by cracking the bleeder after depressing the brake some fluid will squirt out then let up on the pedal and it should suck some air in just do it once or twice then close it all up.

    I know it sounds crazy letting air into the system but it gives you the option of the rear locking up or not, press harder to lock the rear.
    I test rode a bunch of new ktm's about 2 months ago and the front and rear brakes was like that (locking up) out of 2 days there was 2 broken arms and 1 broken leg not me but other people
  6. mudpack

    mudpack Rookie DRN Member

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    I have no complaints.
    I do know that riding boots take away a great deal of "feel" from the rear brake pedal. If you are used to riding in street shoes/boots and get a pair of real riding boots, it can make you feel like a dufus for awhile....
    If this isn't your case, then you can cut/grind away part of the rear pad's friction material, thereby reducing swept area. This reduces braking power.
    Sr5's suggestion is another good one, if you're willing to play with it a bit....keep in mind that it doesn't take much air before you end up with a brake pedal that goes clear to the ground before brake lockup. A little here goes a long way.

    Mud
  7. longtime coming

    longtime coming Rookie DRN Member

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    I have no problem with my boots. I have ridden many other bikes with more progressive rear brakes (I get to ride my kid's bikes and most of their friends' too). Then I get off the demanding race bikes and love my "couch". Everything else does not go from "off to on" like mine. I am afraid of letting air into the system. I warped a road bike's rotors in one pass down a mountain hill because I didn't bleed them good enough. I think the air expands and applies pressure to the rotors when hot. I just need a different pad compound, I'm pretty sure. Or change the leverage ratio some how.

    I don't know. Thanks for the replies.
  8. SVandal

    SVandal Rookie DRN Member

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    I'll put in a vote for pads along with checking your rotor. If the rotor is warped it can cause this and if the pads are too hard they will take a lot of force to start grabbing. I've had stock KDX rear brakes and stock CR brakes and both have been fine with decent pads.

    Then again, in the sand/gravel around here the rear brake is almost an on/off anyways due to the lack of traction.
  9. sr5bidder

    sr5bidder Rookie DRN Member

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    this comes from my current vw rail project and I'm sure its to complex for you but I'm putting in a proportional valve to ease front braking action due to the front being so light i dont want them to lock up under normal braking

    but like I said too extreem

    longtime your kids brakes are drum aren't they ...world of diff.
    I have no prob with my rear brakes but I let the "glaze" be on the rear as much as posible cuz the mud seems to deglaze the rotor pretty quickly I also have lowered the pedal to 1/2" below the foot rest
  10. longtime coming

    longtime coming Rookie DRN Member

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    Thanks for the vote of confidence SR5. Yes, that "proportional valve" blows my mind. What is that? Can I adapt that to my bike? Where can I get one? If I put two on my bike, will that be better? I'm sure I need at least one of those (as soon as I figure out what it is).

    SR5, my kids and their friends are all riding current MX bikes of various displacements and brands.

    Good luck with the rail. Those are cool. My buds used to build those with VW engines 30 yrs ago.

    Can we stop now SR5?

    I don't like the air in the lines idea. Not for me. But thanks for the suggestion.
  11. glad2ride

    glad2ride Rookie DRN Member

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    Have you checked the rotor for warp?

    It sounds like you have had it since new. Have you replaced the brake fluid?

    How old are the pads?

    If all the above are in order, I would suggest you try a different set of pads.
  12. mudpack

    mudpack Rookie DRN Member

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    ...which takes us back to the original post:
    Personally, I don't think the problem is in the pads.
    I could be dead wrong but, without riding your bike, I don't think different pads will be your answer. The fact that this isn't a chronic KDX issue is why I say that. MY guess is that there is something with your bike and/or your riding style that is causing this issue. Without being there to observe, it is hard to say what would cure it. Keep us posted.


    It is a device that allows you to adjust the proportion of braking (line) pressure between the front and the rear brakes on a linked system.
    Your bike does not have a linked brake system, so a proportioning valve will be of no use to you....not unless you want to go to the effort of tying the front brake into the master cylinder for the rear brake, which would require a new, larger master cylinder (among other things), and the commensurate effort and expense.....and, on a bike, would more likely create more problems than it would cure.
    Last edited: Jan 15, 2009
  13. SVandal

    SVandal Rookie DRN Member

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    The Honda CBR1000XX had proportional braking, but I've never heard of it on a dirtbike.

    As for pads, do you have the stock pads still on the bike? If not, then this could still be the problem as you could have a bad set of pads. Otherwise, as others have said, check the rotor for warpage. Or, look at the rear caliper to make sure it isn't binding. However if it was it would drag all of the time so your rotor would be smoking. After that all you can do is adjust the brake lever and live with it. The master cylinder is doing its job, the lines are doing theirs, and the caliper appears to be doing its job as well.
  14. mudpack

    mudpack Rookie DRN Member

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    I have seen a small device that replaces the caliper bleed screw. It is, in effect, a very small air chamber. It supposedly does the same thing as allowing a little air in the caliper; makes it require more pedal travel to produce the same clamping force at the rotor. I wish I could remember who made it....
    Last edited: Jan 16, 2009
  15. longtime coming

    longtime coming Rookie DRN Member

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    I'm going to replace the fluid first. I know what a "proportional valve is"; I was trying to be funny. SR5 was trying to make me small with his "vast mechanical knowledge". That pissed me off. I now know that others don't have my lightswitch brake, so it's something wrong with mine. I'll make it work better, I'm sure. I spend way too much time trying to make the kid's bikes perfect, and mine always suffers. Thanks to all.
  16. marksilvia.cpa

    marksilvia.cpa Rookie DRN Member

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    Try New Brake Fluid

    If you drag the rear brake on a KDX, it will get hot enough to boil the fluid and you will lose any progressive feel in the pedal. Get some new, quality fluid like Motul, and get your hands on a Mighty Vac and suck new fuid through the system until you have purged all of the old, most likely black, burned fluid out of the system.

    I have two nephews and a friend who ride KDX's, we purge the fluid out of both the front and rear annually. Burned fluid, or fluid with moisture in it just doesn't work well.
  17. mudpack

    mudpack Rookie DRN Member

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    If you boil the brake fluid, you will have an EXTREMELY soft brake pedal, one that will provide excessive travel before the brake starts to react.
    Brake fade from either boiling fluid or pad overheating will not give you a hair-trigger/on-off toggle switch brake; they will give you "NO" brakes. :nod:

    That said, replacing brake fluid that is more than about 2 years old really is a good idea........
  18. marksilvia.cpa

    marksilvia.cpa Rookie DRN Member

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    Mudpack,
    I was reading the problem as an on/off feel to the brakes, I missed the part about the hair trigger. I agree that in most situations, burned or contaminated fluid will give you a mushy feel. I have seen in many cases with contaminated fluid, you push the pedal down and nothing happens until the brakes lock up, giving you an on/off feeling. This is especially true with a poor pedal adjustment.
    I have had a few come my way,with brake problems,with new rotors and pads, only to find the fluid was like tar.
    Just trying to help with fluid suggestion-
    I tend to replace the fluid before I start troubleshooting.
    The fluid seems to be overlooked often, but is a critical (though inexpensive) component of good braking.
  19. SVandal

    SVandal Rookie DRN Member

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    Fluid fixed my mushy rear brake on my KDX. Flushed all the brown/dirty fluid until it ran clear. Worked much better.
  20. sr5bidder

    sr5bidder Rookie DRN Member

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    no I was not trying to insult you I was just saying it would be rather complex and take alot of space for a dirtbike thats all man.

    Di you find out way its locking yet?



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