Hey all! I was just heading out on my new to me 2014 Fatboy for a ride (yep, Florida), and I just got a mile down the road and the front brake locked up and would not release. I had noticed the front brake lever getting very "stiff" and the last time I braked which was just before the lockup. I tried pulling repeatedly on the front lever, but i couldn't move the bike in neutral (bc the front brake was on). Ok, so now my question: Is it more likely the front caliper or the master cylinder that is the problem? I noticed the front pads are worn, but not to the metal backing plates just yet. Bike has 30K miles on it. Could caliper pistons have gotten dirty and stuck out and unable to return? ( I was able to free the brakes by prying the pads back away from the rotor with a screwdriver). After writing this, I'm thinking, remove front caliper, spray and clean pistons where exposed, install new pads, retry braking?). Or, do i need to do more, like rebuild caliper? Thanks for any suggestions, my life depends on it!
Jerry
PS Front rotor is warn also, have to measure thickness, might have been a long term problem? Might need new rotor also.

 

I had that problem about 15 years ago , I did a front master cylinder kit first , that didn't fix it . So I did the caliper kit . It was dirty caliper pistons , they wouldn't go back in ., no problem since .
Thats a nice lookin Ride you have .
Good luck .

 

Loosen the bleeder on the caliper slightly - if it releases it's not the caliper.

 

Every 2 years when I bleed both front and rear brakes , I clean the cylinders/calipers and check the pads and rotors , adding new anti seize to the back of the pads and pins .

A good friend of mine had the same issue , his pistons were stuck open and wouldn't retract , bought a rebuild kit and got them cleaned up , good to go . His calipers were the worst I've ever seen !

Your right ! It's your life , wheels and brakes are going to keep you alive , good luck !

 

There is a small hole in the master cylinder that is the return for the fluid. If it gets plugged up (which is easy because it's tiny) the pressure to the caliper builds until the brake locks. If opening the bleeder releases the pressure and it's OK for awhile but then locks up again after use it is a pretty good indication that the return hole is plugged. Over the years I've had it happen on a couple of bikes and several old trucks. A fine piece of wire or high E guitar string will clear the hole. Just go easy with it and don't get it jammed on the piston.

 

Thanks guys for the suggestions! I’ll let you know what I find. Much appreciated!

 

Moisture in the system will cause that. All of the above and bleed your brakes as the fluid is probably contaminated. When your brake fluid has moisture and the fluid heats up (in the caliper) the moisture transitions and expands as moisture (water) will goes from liquid to vapor. This expansion in the system causes the issue you described.

 

I've never had that happen to me. But I read something in the service section of Cycle World magazine that describes a plugged up return as a cause. They also wrote that a warped disk could generate heat and cause the brake fluid to expand and push the brake pad against the disk causing more heat, more expansion, more heat, etc. until the brake was locked.

 

I once even saw that problem on my friends Kawasaki with a Hydraulic clutch. The clutch release would pump up until the clutch started to slip, opening the bleeder would temporarily fix the problem until he could get it home and clear the return port.

 

I hope to check it out more today, I’ll report back what I find. Thanks again for the suggestions!