Rear brake - way too weak (950)

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by BOB RAMSAY, Oct 9, 2012.

  1. BOB RAMSAY

    BOB RAMSAY Not in the Clique -

    Joined:
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    My rear brake is about 5% effective - actually, more like 0%, as I cannot stop the bike, even under 10mph.

    A little history:

    2006 950 Adventure
    OEM pads/rotor, 24k miles (all road).
    Pads 6mm thick.
    Had a light oil contamination on pads/rotor last week (don't ask. . . ).
    Pulled, cleaned and sanded pads and sanded rotor today. Nada.
    Fluid changed summer 2010. Free play is good.
    There is some pressure at pedal, no pressure being applied to the rotor.

    Can the wheel cylinder 'blow by' the seals when the brake is applied?



    Any help would be appreciated. Thx -
    :jinx
    #1
  2. Off Road Ryder

    Off Road Ryder Long timer

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    personally I like sintered Iron brake pads,They bite hard, but do wear your disk.
    Im always draging my rear brake, (bad habits are hard to break) I replace my fluid about once a month, Its amazing how quick the fluid can go to crap.
    #2
  3. veesquared

    veesquared Been here awhile

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    Assuming you do not have air in the lines from a tip over . Can you lock the rear wheel on asphalt? Try cleaning the rotor again with your favorite solvent . You might find that you have squeezed out more oil. If no go them I too would go with a different compound. 6mm must be pretty close to new.
    #3
  4. crofrog

    crofrog Long timer

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    2010, I do that like every 6 months...
    #4
  5. txbear55

    txbear55 Been here awhile

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    New pads....
    #5
  6. Sporting Wood

    Sporting Wood I

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    Galfer Green pads! Stock ones absolutely blow!
    #6
  7. Roughidle

    Roughidle Super Star Destroyer....

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    Must be some different riding styles out there, I grew up on dirt bikes in Michigan and I used the rear brake ALL the time. Too much front brake = lowside. But I digress, that isn't really what the post is about.

    Did you ever get the reservoir diaphragm upgrade? KTM sent out a service bulletin about it back in 07 IIRC (took my 06 950a in for it). The bulletin called for a new diaphragm, and a rear brake bleed.

    If I was in your shoes, I'd ensure I have the upgraded diaphragm, pick up a new set of galfer pads as others have suggested, and properly bleed the brakes.

    You can check it for "blow by" or leaking cylinder seals by doing the following:
    Pump the rear pedal 3-4 times and hold pressure on it, if it starts to slowly move as you apply pressure, then it needs a rebuild. If it stays in the same position after you pump it a few times and hold it, then the cylinder is fine.

    Ideally, you should be able to lock the rear brake on dry pavement on these bikes, I was always able too with my 950.
    #7
  8. Mttodd

    Mttodd Adventurer

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    Bought my 06 last summer and would like to know how to identify the improved diaphragm. If I do have the old version is the new one expensive, or supplied like a recall? Noticed that my rear brake pedal has a lot of play before it engages. It does not have any adjustment like the newer models, and was looking for some pointers.
    #8
  9. Roughidle

    Roughidle Super Star Destroyer....

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    Brake TSB with pics: http://cpmodem.smugmug.com/gallery/2529765_MRKpm#!i=132944527&k=PppNc

    From here: http://www.ktm950.info/

    Just bookmark the HOW link. I actually copied all the articles into a big book when I had my 950, just in case. :evil\ Big props to CPmodem as always.

    Really? Aren't there adjustment nuts on the pushrod? It's been a while, and I could be wrong, but I thought there were adjustment nuts on the pushrod. I seem to remember adjusting the pedal height after installing new/ lower pegs.
    #9
  10. mgorman

    mgorman Crashing since 1964

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    For what it's worth, my 04 (rebadged 03) brakes suck so bad, even standing on them barely slows the bike. At least I don't have to worry about stalling it off-road.

    I took mine in for the brake upgrade because they kept fading/going away and getting limp. After the new parts were installed it was hard as a rock but sucked. One day it stuck on so I had to disassemble the master cylinder and free the stuck piston. Cleaned it all up and still no better. A few days ago I took the caliper apart and both pucks moved freely but were looking pretty bad. The edges were crumbling away like bad concrete. This winter I am rebuilding them, sanding down the rotor and trying to find a set of pads that will actually grab.

    EBC, KTM and another brand all sucked. The off brand I bought on ebay was so bad I wore them out in 4k miles and had to replace them on my trip, twice in 8,000 miles! I just tried a set of organics from the front of a MX bike, suck too

    When I ride by myself it is tolerable but loaded 2 up gets a bit scarly when you need that extra boost.

    Thinking maybe some 80 grit sand paper glued to some old backing plates would be the best route
    #10
  11. crofrog

    crofrog Long timer

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    Keeping digging man. I'd make sure the caliper is floating freely, get the rotor re-cross hatched and stick some oem pads back in there.


    My stock 950 brakes will easily lock the rear tire, but with good modulation.
    #11
  12. Mttodd

    Mttodd Adventurer

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    There is adjustment on the pushrod (some). I was looking at an 08 990 and it had an additional adjuster up near the fulcrum to tighten up the whole assembly. Mine doesn't even look similar. Still curious about the improved diaphragm.
    #12
  13. Bgunn

    Bgunn Mucha distancia

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    A fluid change brought my rear brake back to life.
    #13
  14. Mttodd

    Mttodd Adventurer

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    Thanks Roughidle for the cpmodem link. I will check to see what I have when I get back to town. Anybody think it would be worth asking KTM or my local dealer to supply one if I do in fact have the original defective version? Apologies to the O.P., did not mean to hijack thread, but this might save others the same headache.
    #14
  15. GrenDesb

    GrenDesb Been here awhile

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    If you bring your bike in, they have to do the recalls if it hasn't been done. They know from their records if the recall has been done.
    #15
  16. Zuber

    Zuber Zoob

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    The rear brake issue on the 950's was a NHSTA Recall, not a service bulletin. So KTM will perform this brake fix if it hasn't been done, for the third owner, no matter how old the bike is.

    On the other side, the recall was to fix a problem with a mushy rear brake.
    #16
  17. K2m

    K2m ....58....

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    This bike more than any other for some reason. Motul 600. Raceing car stuff changed as regularly as necessary depending on your riding style. That's how I do it after the upgraded parts were fitted. I do mine once a year.
    #17
  18. BOB RAMSAY

    BOB RAMSAY Not in the Clique -

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    I kept your comment in mind as I've waited 2+ weeks for a brake cylinder rebuild kit (still back ordered 3+ more weeks)

    My bike did tip over, just against a wall - no more than a 45 degee lean angle. Still, the brake system was never 'breeched' so I don't how air would have been introduced to brake system.
    Yesterday, I bled the rear brake - Voila! Went ahead and flushed out the old brake fluid with new DOT 5.1

    My background is with enduro and off-road riding. I've had bikes up-side-down (and worse!) Never considered the 950 being tipped over to be the culprit.
    Whether is was or not - IT WORKED.

    Thanks for input. I've been able to do some repairs with simple wisdom from the inmates. Other suggestions seem like the end of the world could near (financially). So, when I need help, I'll take all who take the time to post/comment.

    Reminds me of Occam's Razor: it goes something like this: "other things being equal, a simpler explanation is better than a more complex one."<SUP style="WHITE-SPACE: nowrap" class=Template-Fact>[</SUP>


    Thx - Bob :jinx
    #18
  19. K2m

    K2m ....58....

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    Plus one

    Simple things must be eliminated first. This will be the problem. This brake runs very hot, this creates moisture in the fluid which turns to air...... no brake.

    I do mine every 12months...... :1drink
    #19
  20. mgorman

    mgorman Crashing since 1964

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    I had mine apart recently, all parts move freely but it still sucks, even though it is firm, I even tried a grippier compound and sanding the rotor. My pucks look like vintage concrete on the mating surface, the material is crumbling away and the flat surface now resembles the moon. My last guess is, the puck not being perfectly flat could be flexing the pads and not getting a full bite against the rotor or binding when under pressure. That'll be part of my winter go-over
    #20