Topic: Brake locked up

[Keith]

I took my bike out today after sitting almost all summer. Between shifts I could feel something dragging. I pulled in the clutch, and the bike stopped like I was applying the brakes. The front rotor was hot, and I couldn't push the bike by hand. Either the caliper or M/C. The brake lever was hard as a rock, didn't move when squeezed. So, I cracked the bleeder, and the bike rolled again. I rebuilt the caliper a few years ago, I think its ok. Rode it home without using front brake.  I suspect the M/C is the culprit, ordered genuine Honda rebuild kit. Ideas?

[Deltarider]

I took my bike out today after sitting almost all summer. Between shifts I could feel something dragging. I pulled in the clutch, and the bike stopped like I was applying the brakes. The front rotor was hot, and I couldn't push the bike by hand. Either the caliper or M/C. The brake lever was hard as a rock, didn't move when squeezed. So, I cracked the bleeder, and the bike rolled again. I rebuilt the caliper a few years ago, I think its ok. Rode it home without using front brake.  I suspect the M/C is the culprit, ordered genuine Honda rebuild kit. Ideas?

What bike... a CB350F?

[Bankerdanny]

I had this issue with the rear disk on my 750F a couple weeks ago. I replaced the rear master which seemed to solve the problem. Since cracking the bleeder allowed the piston to retract then I think you are on the right track with the master. There is a port that allows the pressure to bleed off when the lever is released. That may be blocked.

Repro masters are cheap, about the same cost as a rebuild kit. I would replace the whole unit rather than rebuild unless you have a concours show bike where originality matters.

[Progas]

In the master cylinder there are two holes at the bottom, one is very small, if that is blocked, that will cause your brake to lock up. It happens all the time!

[Keith]

That's my thought. K2 750, want to save original M/C for show. Thanks!!

[Marks78]

 What is the condition of the brake hoses and how old are they? As they age they can start to develop internal cracks that allow a sort of flap of rubber to form that sometimes allows fluid to flow one way but blocks flow the other direction.  If none of the other fixes work try replacing the brake hoses.  Best of luck!

[ekpent]

 Already mentioned but its either a blocked return hole in the master or a bad brake line that has collapsed. The fact it released when you loosened the bleeder points to one of those two issues.

[Keith]

Thanks all. Collapsed hoses were common in the auto business when people used visegrips on the hoses. I ordered the m/c kit, will order the hoses too.

[ekpent]

Yup -  I've had to replace multiple rotten rubber brake hoses on old cars over the years when the brakes start seizing up. Your problem might be fixed by poking a strand of wire through a hole in the MC. I find one strand from a wire brush is the perfect size.

[jus4selling]

Stainless braided hoses are worth every penny if you're overhauling the m/c anyway...