Topic: CB550 front brake

[calal]

I also have a problem with the front brake on my project 550.  I rebuilt the front caliper, and found a decent master cylinder on ebay - the original master was too far gone to use.  I've ridden the bike only a few miles, and the brake works ok, but it seems that if I leave it parked in the sun, all the play goes out of the lever, and the pads start to drag - like the fluid is expanding?  If I crack the bleeder screw and let out a bit of fluid, the drag goes away.  Could this be that the compensating port in the master is blocked?  I also notice that the rotor isn't centered in the caliper, it's outboard a bit, with more of the inner pad visible - is this a concern? 

Thanks again

[Bankerdanny]

You center the caliper using the screw on the caliper arm. This has to be adjusted periodically as the inner pad wears

[calal]

But if the inner pad isn't worn much, it's normal for the rotor to be off-center (to the outside) in the caliper?

[flybox1]

brake lines with air bubbles, heated in the sun, could cause enough pressure in the line to build up to push the pad....lever action would only compress the bubbles and not so much move the pad for more contact.
if the piston seal is old and not doing its job, proper piston retraction is less.  did the seal groove get properly cleaned and a new seal get installed?
what is the condition of the piston itself?

[Bankerdanny]

But if the inner pad isn't worn much, it's normal for the rotor to be off-center (to the outside) in the caliper?

Don't worry about centering the caliper. Center the rotor between the pads. The two pads won't necessarily wear at the same rate.

[calal]

I'll bleed 'em again, but the lever is really firm - doesn't feel soft like there's air in the lines.  Caliper rebuild should be good - I've done several before this one...

[jonda500]

There will always be more of the inner pad visible as it doesn't sit inside the calliper like the outer one.
John

[Bodi]

Unless the relief hole in the m/c is blocked, no pressure can build in the system when sitting. Check the m/c.

[strynboen]

yes the tiny return hole is blocket.
.so there build pressure up in the trapped fluid
..better take the marster off..and klean both escape holes..and take the piston aut..and polish the bore...a lot of dirt/korosion can accumulate inside this system..and often the dust seel is rotten to death