Front Brake Fluid Master Cylinder Problem

Discussion in 'Wheels' started by THE BOGGER, Jun 21, 2010.


    THE BOGGER Member


    1997 Ultra classic front brakes are acting very strange based on Temperature change. it is acting like the Brake fluid is expanding and causing the lever to be become very stiff.

    In the morning I ride the bike to Work, the front Brake lever is acting normal, about an inch of travel to full brake application. When I get on it to ride home in the afternoon. The front lever is very much expanded and there is about 1/4 inch of travel and slightest touch of the lever and the brakes are locked up.
    It is acting as if the fluid is expanding in the brake reservoir.
    I changed out the Brake Fluid yesterday and put in the Synthetic fluid also cleared the lines and filled it back up. checked the lever action it was normal at 11:00am. Now I went back to the bike at 4:00pm and the lever was expanded again and acting just the way it was before changing out the fluid.

    I am stumped and wondering if the Master cylinder is defective. Is the problem just the calipers or the master. I cannot believe anything has ever happended like this before. Any thoughts or suggestions would be appreciated.
    I am not sure the brake fluid would cause this problem if the bike is standing still, only if you are riding for a long time the fluid would get hot.

    Thank You
  2. glider

    glider Veteran Member

  3. Jack Klarich

    Jack Klarich Expert Member

    Had a similar problem with a 97 FLHT, as it turns out the dot 5 fluid crystalizes and causes all kinds of problems, try flushing the system with the correct fluid:D