I have an 05 FLHTCSE2 and recently had my rear caliper seize up while riding. (Thank goodness it was at low speed) I removed the cap from the master cylinder to find there was no fluid in it. I released the pressure from the caliper and got the bike home then filled up cylinder, bled the brakes and headed out. 1/4 mile down the road the caliper grab the rotor and would not let go. Released pressure and returned home. Mind you as long as I don't step on rear brake pedal there's no problem. I changed out caliper and brake line just to start process of elimination and problem still persist. Could the master cylinder be damaged? Brake fluid being used is dot 3-4 synthetic could this be the problem? HELP PLEASE........

 

You didn't fix the problem. Fix the rear caliper. Most likely you have a piston seizing and not retracting. No fluid in a sealed system should be a serious clue that something is seriously wrong.

 

Make sure the caliper bushings and pins are not worn or your rear wheel is not way out of alignment. If the caliper is not lined up with the wheel it can cause a lot of drag.

 

I've had the master cylinder cause this as well, it is easy to rebuild and the kit is not that expensive, if relieving the pressure resolved the problem I would look at the master cylinder.

 

It could also be a crack in teh master cylinder.

 

Rebuild the caliper completely with piston change your fluid purging all the old fluid. Take FINE emory clothe to the piston bore to clean it up. Good time to rebuild the master cyl too. It doesn't cost much to do all of this and is only a couple hours work. If our master is leaking there will be fluid somewhere on it.Don't forget the o-ring washers for the caliper.Good time for pads if they are even questionable.

 

Since you've changed the caliper. I would say to change or rebuild the Master Cylinder. I had my buddy's bike do the same thing. The fluid in the reservoir was clean and clear but when I took it apart the cylinder bore itself was so gunked up it's a wonder he had brakes at all.

 

If you released the pressure and the brakes let go.........Then everything at the wheel is working just fine.......the problem is at the master cylinder. The only other thing it could be (and this is rare) is a mechanical bind at the brake pedal arm (not returning when applied)

 

Da missed the part about the new caliper. The rest still works though. Blow the line out.

 

DA HAWGSTA--Read this again.^^

If you released the pressure by turning a bleed screw its the same as you releasing the pressure from the control. No pressure on the pads that means everything at the wheel is working.