Rear brake drag..warped rotor?

[GrumpyGuts]

After finally bleeding the front brakes, the rear brake still remains a problem (bled absolutely fine)

It is dragging. Not sure if it is due to the wheel alignment, however I replaced the chain and it is adjusted evenly on both sides.

When I look at the brake pads, the right pad does not spring back (piston clearly retracted back into the bore) with the left pad still touching the rotor. The wheel is easier to turn when I move the right pad manually back against the piston but when I pump the brake, the pad does not come back. When I move the bike you can hear the pads dragging but the bike is not difficult to move.

Any ideas? Fucked pads? Fucked pad spring? Warped rotor?
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My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[Aff]

Take the caliper apart and give everything a good clean and lube.
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Current Bikes:Honda 929RR Fireblade, Honda CD200 Benly (Project), Stomp Z2 140
Electric Bike Project

[cimbian]

Rotor? ROTOR? Waddya mean rotor?... Too much Yank.

I suspect it is just a case of cleaning the calliper. The return movement of the piston is very slight as it is basically just the flexing of the seal so it is often imperceptible.

Unlikely to be a warped DISC unless you hear the binding come and go as the wheel is rotated.
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22PlusY
Current: Moto Guzzi 1100 Breva. Previous: Honda XL650V TransAlp
Bearded, Balding, Born again Buddhist Biker

[Kickstart]

Hi

Is it a single piston sliding caliper? Ie, piston on one side and as it pushes the pad onto the disk it pulls the whole caliper across, pulling the other pad onto the disk?

If so then I would suspect that the caliper is sticking on the pins it slides on. Afraid if so it is time to take the caliper off and pull the carrier off the caliper and clear it up and lube it.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[GrumpyGuts]

The piston is a single. The rear caliper has been stripped, cleaned and lubed with clean brake fluid with new seals. Also used was copper crease on the pad pins and the back of the pads.

The piston is clearly seen to be retracting AWAY from the pad. However, I have been told my a couple of people (one qualified mechanic) at work that you may need to ride the bike to rebed the pads into the caliper since it has been removed several times (trial and error, cleaning etc etc). I've also rebled the caliper again to make sure every last air bubble is out (a few more came out second time round and now it's just fluid)

I'm going to give it a blast down my street (hopefully away from any coppers) to see how the brakes are performing and if the disc is hot to the touch.

I'll let you know what happens. The bike is not difficult to move albeit the dragging noise you can hear.
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My Bikes: Lifan Beat 125cc '11 -> Suzuki B120P '76 -> Suzuki EN 125-2A '08 -> Honda CG 125 '04 -> Honda CB600F Hornet '98 -> Kawasaki ZZR 600 '99 -> Kawasaki GPZ 500S '95 (Current)
Theory test passed - 09/02/2012 >>>> Module 1 passed 24/07/2012 >>>> Module 2 passed 24/10/2012

[cimbian]