YZF426 rear break won't release

Discussion in 'Thumpers' started by llirttoc, Mar 4, 2011.

  1. llirttoc

    llirttoc Ural Life

    Joined:
    Aug 23, 2006
    Oddometer:
    182
    Location:
    cambridge, ohio
    Some history on this: First time rear break locked up. Checked fluid discovered reservoir was distorted, guessing it's from the closeness to the pipe, and no fluid in res. more like mud. Replaced reservoir, flushed with copious amounts of fluid. Still locks up. Removed caliper. Tried to compress with C clamp. Still locked. Cracked open bleeder and boom caliper moves freely. Is there a check valve in this system thats not working? Need new caliper? Am I doing something wrong?
    Thanks for any help.
    #1
  2. trailsaw

    trailsaw remember tomorrow

    Joined:
    Sep 18, 2010
    Oddometer:
    564
    Location:
    Guff Coast
    If the caliper has "freed" up it's your brake line that needs replacing.
    The inner core can break down and act like a one way valve.

    For good measure rebuild master cyl and caliper too-cheap and easy.
    #2
  3. llirttoc

    llirttoc Ural Life

    Joined:
    Aug 23, 2006
    Oddometer:
    182
    Location:
    cambridge, ohio
    will try new brake line, and check out rebuild kit.
    thanks again, trailsaw
    #3
  4. trailsaw

    trailsaw remember tomorrow

    Joined:
    Sep 18, 2010
    Oddometer:
    564
    Location:
    Guff Coast
    Very welcome!

    Post up results when complete....


    BRAAAPP:lol3

    PS-check pedal linkage for free movement also/grease as needed.
    Use the best fluid you can and flush 2 or 3 times ayear----at least:deal
    #4
  5. LILBIT

    LILBIT Ride you must.

    Joined:
    Oct 17, 2007
    Oddometer:
    1,675
    Location:
    Lake Placid, FL
    No air in the res. and the cap screwed down tight will lock the brakes. Crack open the resevoir and see if it unlocks.
    #5
  6. llirttoc

    llirttoc Ural Life

    Joined:
    Aug 23, 2006
    Oddometer:
    182
    Location:
    cambridge, ohio
    When I had the caliper off but still hooked to reservoir, I had cap off to see if fluid was pushing back in, and it was not. Thanks for the tip. Ordered new hose, local shop did not have in stock.
    #6
  7. llirttoc

    llirttoc Ural Life

    Joined:
    Aug 23, 2006
    Oddometer:
    182
    Location:
    cambridge, ohio
    After my last post I called the LBS to order a new break line thinking it's only gonna be 20-30 bucks. They said they would have to order, as I suspected, then I said WTF 89 bucks, I don't think so. I went to eBay, found one used for 10, ok that's better. I know that things take while to get shipped out. Decided to take everything apart on the rear break system, clean, inspect and reassemble. The system works better without mud inside the master cylinder :rofl. Took a test ride, seams to be working now, if anyone cares.
    #7