My rear brake is dragging

[Noreg]

Its like making a scraping noise and its warm even after not using it.

Any suggestions?

[FlordiaMan]

Its like making a scraping noise and its warm even after not using it.

Any suggestions?

what type of bike is it?

[Noreg]

what type of bike is it?

1981 gs1000g.

[Brendan W]

Pads sticking
Piston sticking
Inside of hose delaminating and acting like a one way valve

[Burque73]

My rear brake was dragging until recently too. The pistons are not retracting back into the caliper after the pressure is released leaving the pads too close to the rotor. May be a bit of corrosion on the pistons. May be some crud from old rubber brake lines in there. Likely a bit of jelly looking crud built up from old brake fluid.

If you haven't replaced the original brake lines this is a great time to install stainless steel braided lines and overhaul the calipers. You won't regret it. I was amazed how much easier it was to walk the bike around after this. With the bike up on the center stand, my rear wheel would not spin by hand easily. If I gave it a spin it would stop immediately. Now it spins easily only stopping by the resistence from the drive mechanism.

If you do go with braided brake lines, you'll notice you don't have to squeeze the brake lever as hard either.

[Noreg]

https://imgur.com/a/F3xvqLV

Burque73 that sounds exactly like my issues. There is a picture there. No idea if original...

[Burque73]

Sure looks original. Those rubber lines are supposed to be replaced every three years anyway.

[bwringer]

It's also pretty common for the rear brake lever pivot and the hole in the frame to get dirty and corroded and start sticking.

Work the pedal back and forth a few times whilst spraying some schmoo in there and you might free it up. Or take the pedal off, remove the pivot and spring, clean things up and apply a good waterproof grease for a more permanent fix. Getting the spring back in the correct spot can be a bit of a mind-bender, so be careful and maybe take some pics.

[Burque73]

...........................Work the pedal back and forth a few times whilst spraying some schmoo in there...............................

That Schmoo is great for removing Schmutz. LOL

[Noreg]

Schmoo? Never heard of it

[Burque73]

Schmoo? Never heard of it

I'm not sure of the exact formula Mr Ringer prefers, but WD-40 should suffice.

[allojohn]

OK the brake hoses should be replaced... have you bled the fluid since you've had the bike? It may not be at all fluid now....

[rphillips]

I'm like Noreg, never heard of schmoo, but the WD-40 will work pretty well on the schmutz. Good luck.

[Cipher]

does this caliper use hard steel pins that the pad backing plates slide on?
If so NB these will rust and cause problems all by themselves. A quick clean with wet\dry sand paper to polish them smooth removes them as a source of trouble.

[2BRacing]

The very small return hole in the master cylinder could also not be completely open, preventing release of pressure after the brake pedal is released. You would need to remove the fitting that the brake hose goes onto at the rear master cylinder, to get access to that small hole.

Use one piece of wire from a wire brush to clean out the hole.

As mentioned above, the seals in the caliper should be replaced, as well as the brake hose. If the pistons are rusted (pitted), they should also be replaced.

Use only OEM parts for the seals. There is also a seal between the two halves of the caliper that must be replaced (note that it is a special seal with "flat" sides, not "rounded" sides like a o-ring).