Fat Boy Rear Brakes leave me scratching my head

    • 27 posts
    March 29, 2011 12:59 PM PDT
    At the beginning of last season I installed new brake pads front and rear on my 99 fat boy. all was well until towards the end of last riding season and the rear brakes started locking up fairly easily, just put new rubber on front and rear, was hoping the new tread would ease the touchy rear brakes a bit. Didn't help and they are almost impossible to apply without locking up, pads a and rotor both look fine. front brakes are perfect, only the rear is a problem. fluid is ok in master cylinder. Any ideas on what could be causing this.
    • 5419 posts
    March 29, 2011 11:50 PM PDT
    First thing I would check is to see of the rear rotor is warped. Put the bike on a stand and spin the rear wheel.
  • March 30, 2011 12:29 AM PDT
    Was everything lubed as it went back togeather? Had a truck that did that and they forgot to lube calipers when they put it back togeather!
  • March 30, 2011 2:14 AM PDT
    While checking to see if the rotor is warped apply the brakes (pump a few times) and assure the caliper is releasing. The inside of flexible brake lines can collapse preventing the caliper from properly releasing.
    • 834 posts
    March 30, 2011 3:06 AM PDT
    I too would pull the guide pins and make sure they are lubed with pin lube. Could be that they are not sliding smoothly so you keep applying brake until they finally go all the way in.

    Bottom line is I would be sure to get this fixed before riding. If you can't find it yourself, go get it checked out at the shop. Brakes tend to be an important feature!!!!!
    • 27 posts
    March 30, 2011 3:19 AM PDT
    thanks for all the input guys, but negitive on all, pins are lubed, pad slides are lubed, rotor is not warped, pads and rotor are clean, brakes release immeaditely when letting up on pedal, non of these would appear to be the problem.
    still vexed
  • March 30, 2011 1:11 PM PDT
    You might try bleeding the systen, put some new fluid in there.  It could be that the fluid is getting tired and when it heats up, expands too much causing a light pad to rotor drag .  Then when you apply the brakes in a heated condition they will lock up due to the excessive heat. 

    Bleed the system, replace with a good quality fluid, check your brake pedal freeplay verify it is in spec, also check and make sure the brake line does not come in contact with a heated component.  If so, re-route it.

    It sounds like something is causing the pads to drag on the rotor and is generating too much heat for efficient braking.

    Thanx,

    jb
    • 844 posts
    March 31, 2011 3:11 AM PDT
    I agree with AZ, if you can't find the problem GET IT TO SOMEONE WHO CAN. I have never seen a brake issue get better on its own, and lets hope it doesn't get worse when you need the brakes the most!!!
    • 0 posts
    March 31, 2011 5:10 PM PDT
    Pull the pads and take a sanding disc to the leading and trailing edges and bevel them at a 45 degree angle. this will stop the edges from digging in.
    • Moderator
    • 19007 posts
    April 1, 2011 12:39 AM PDT
    Judging from the replies and your followup it looks like the only thing left is the brake fluid and possibly an internally corroded caliper or master cylinder causing the pads to stick. Since it is a '99 it is possible the fluid is original. A complete flush and replace is what I would do next.
  • April 11, 2011 6:16 AM PDT
    you need a caliper rebuild kit... it's probably due and if you have the right tools it's easy.
    • 27 posts
    April 11, 2011 6:34 AM PDT
    thanks for all the advice took everything apart cleaned, lubed, reassebled, adjusted tire pressues, and everything seems fine now. I suspect the tire presssure was the biggest but not only culprit. the palce where i had them mounted had 55 lbs in them, reset to factory recomended pressures.