Baffled by my rear brake binding! Help?

vladthetodge · Two Stroke Sniffer Joined: 03 Mar 2015 Karma :

I posted before about this, and your sound advice fixed it.... Or so it seemed. Now it's still binding.
Here's what I did. Removed and totally stripped both the caliper and the master cylinder. Removed and clean the pistons, seal and used brake cleaner etc. All as shiny and clean as a whistle. Stripped and cleaned the master cylinder, all seals perfect. Replaced everything as it should be. Bled properly. Less than a hundred miles in its started to bind again! the only thing I can think of that's common to each time is the master cylinder. The brake pedal has a distinct extra free play on the day that it starts to bind. The pedal itself doesn't stick. Could it be as simple as me adjusting the brake pedal height having this happen? It could I suppose cause the plunger on the cylinder to go in too far and stick maybe?
I have no idea what else to do but replace unless you guys have any ideas?
Cheers all

sickpup · Old Timer Joined: 21 Apr 2004 Karma :

Did you clean out the seal gaps under the seals? If not this is likely to be the problem, detritus under here forces the seals out against the piston causing binding.

davebike · World Chat Champion Joined: 15 Nov 2013 Karma :

If you adjusted the leaver hight did you check there is still free play at the master cylinder with the leaver at rest ??
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vladthetodge · Two Stroke Sniffer Joined: 03 Mar 2015 Karma :

Yeah I took the seals out, cleaned behind where they sit. Tbh it wasn't really crusted up at all. The free play on the pedal. Hmm... Maybe not a lot. I'll re bleed and adjust again making sure there's free play and see how it goes.

CBRMAN94 · Nitrous Nuisance Joined: 10 Jun 2013 Karma :

Have you checked the bores of the caliper and M/C? Slightest bit of corrosion in the wrong place can cause binding
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Speedy2007 · Renault 5 Driver Joined: 24 Oct 2013 Karma :

Have you got metal shields on the back of your pads? On my Blackbird they were twisting at an angle and sort of locking the pads to the disks. Removing them made no difference to braking but stopped the binding.