Rear Brake Seizing

twinegar · Post by **twinegar** » Sun Jun 15, 2008 10:51 am

The rear brake seized in the driveway after the first test ride. I rebuilt the caliper and it did it again and I then moved to the master cylinder and noticed that the pin that unites the cylinder shaft to the brake lever is missing. would this account for the brake pads not releasing? Is the brake pedal returning to the park position and pulling the cylinder shaft back out what it takes to release the brake?

steve murdoch icoa #5322 · Sun Jun 15, 2008 8:19 pm

It makes sense to me that the brake fluid is staying under pressure in the brake line and caliper if the master cylinder piston is not returning to the static? position.

twinegar · Post by **twinegar** » Wed Jun 18, 2008 10:23 am

I took the fluid feed tube off and see 2 ports. The feed port is open and flowing but the return port almost looks like there is no hole at the bottom of the port. I am going to use a micro bit to clear it unless someone has a better idea. I have done this on a couple of my other bikes but never on a rear master. I guess they all work the same?

twinegar · Post by **twinegar** » Wed Jun 18, 2008 10:30 am

Never mind, I found another post dealing with this.

alimey4u2 · Post by **alimey4u2** » Sat Jun 21, 2008 2:54 pm

Blocked compensator port me thinks...

twinegar · Post by **twinegar** » Sat Jun 21, 2008 4:08 pm

It was. I used a #80 drill bit and cleared the hole. I wonder why Honda doesn't make a larger return hole. I enlarged the hole on 2 of my CB750's while I had them apart and it works fine. Maybe they use a tiny hole so when brake bleeding with the cap off fluid doesn't squirt all over the place.

alimey4u2 · Post by **alimey4u2** » Sat Jun 21, 2008 5:20 pm

I think a tiny hole is to control the speed of return to rest of the pucks ( hence brake pads) using hydraulic dampening.

Dave Ditner · Post by **Dave Ditner** » Tue Jul 08, 2008 4:42 pm

The reason for the small hole size of the compensating port is pressure generation. Sizewise the master cylinders are marginal. The larger the hole the farther down the bore the piston must be to start generating pressure, and they can't afford the wasted space.

alimey4u2 · Post by **alimey4u2** » Tue Jul 08, 2008 5:29 pm

Dave Ditner wrote:The reason for the small hole size of the compensating port is pressure generation. Sizewise the master cylinders are marginal. The larger the hole the farther down the bore the piston must be to start generating pressure, and they can't afford the wasted space.

Thanks for that Dave, makes perfect sense....

Ps. We miss you...

The International CBX Owners Association

Rear Brake Seizing

Rear Brake Seizing

Master cylinder

Re: Master cylinder