New brake pads binding for first few miles

[Cigaro]

Hi,

Got my new pads in, rebuilt calliper and master cylinder etc. Took it out for a few miles last night and noticed the brakes binding quite badly on one side. However they seem to have loosened up a bit now (though they're still doing it a tiny bit). Is this normal for new pads? Could it be that the disc is slightly worn on one side?

Cheers

Rowan

[Odie]

No its not, you have screwed some-thing up, check to see if you have fucked up putting the seals back inside the caliper, causing them to grip the piston and not allowing it to return.
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[alun111]

Did you clean up the groove where the oil seals sit to get rid of corrosion before fitting the new seals. Did you use the old seals? If so were these in good condition, with no cracks/scoring - did you clean these off (they can become covered in corrosion from the aluminium oxidising). What were the pistons like? Pitted? If so then that raised bits will be causing the brakes to bind by sticking on the seals.
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[Kris]

Did you put the seals in correctly? Some have angled sides which must sit in the correct position against the piston...
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[Cigaro]

The first bit of the problem may have been that I missed out a little metal clip when I was putting the pads back in the calliper and putting it all back together. So that's back in now, but it still does it.

I've spoke to the shop who rebuilt it and it turns out they only did the master cylinder, not the calliper. It seems likely that the piston is sticking due to that being the normal position when the old (quite badly worn) pads were in.

I had to have the master cylinder rebuilt because I put the wrong fluid in so it's possible that also fucked the seals in the calliper.

The binding isn't that noticable, though the bike is slightly harder to push. Went on the motorway this morning though (one junction) and SMOKE was coming from the pads when I stopped! So I think I'll have to take the calliper apart and rebuild it myself (can't afford to have a mechanic do it).

It's not possible that the pads will bed in on their own, is it? It seems to free up more every time I ride it, though that could just be wishful thinking on my part.

[Coxyzxr]

Sounds like you didn't reseat the pistons correctly, though how you got them back on and pads over the disc like this is baffling if that were the case.

I would't trust it like this so wouldn't wait for it to 'bed in'

You may need to (gently ) push the piston back in the calipers forcefully with a vice and 2 peices of wood over each side (piston and rear of caliper to avoid damage) and close the vice to properly psuh the piston in it's seat properly.
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[Cigaro]

When I got the brake system back the piston was already pushed back in for me, but after putting the pads in and bleeding it that's when it started binding. When I took the calliper back off yesterday I noticed the piston was sticking out about 1cm, but this left more than enough clearance to install the pads.

I suppose I could pop it back in again but surely as soon as I used the brakes it'd only stick back out again?

Overall the brakes feel firm and very strong when applied, but I suspect the heat would cause fade on a long journey at the moment.

Could it be bled incorrectly? I've tried re-bleeding it (slacken off bleed nipple, pump brake so fluid comes out, hold lever down and tightning again), is this right?

[Cigaro]

I bled the brakes up a few more times and it's stopped binding now. What I did was pull the lever in until it just started to bite, then undid the bleed nipple letting a bit of fluid out and did it back up again, thinking this would 'suck' the piston away from the disc. Correct or not, it worked

[Odie]