Rear brake will not work

I am having a problem on my rear brake on my 1981 KZ1000 CSR. I have very little pedal movement and very little stopping force on my rear brake. This was a sudden happening. If I stand and put a lot of pressure on my pedal, it will stop a little better, but not much.
I have taken my rear master cylinder apart and every thing looks and acts fine. I have taken my rear caliper apart and it looks fine.
I have fairly new brake pads. If I crack a line or the bleeder valve, it will bleed normally. When I close the lines or valve, the pedal will barely move.
What am I missing? I am about ready to give up.
Help!

is the brake pedal moving freely on its pivot?

That is a tough one. I can only think to take the rear caliper off, leaving the brake line attached and apply the rear brake to see if the piston is moving freely.

Robert

Yes. With the caliper off, you can pump the piston right out of it.

saltydog wrote:

Yes. With the caliper off, you can pump the piston right out of it.

Am thinking either the pads aren't squeezing hard enough against the disc, or if squeezing hard enough, something's interferring with necessary friction between pads and disc.

With caliper off, to help determine how hard the pads are gripping the disc, could place a soft lead fishing line weight between pads and firmly apply brake to determine extent to which the weight is flattened.

Might also compare results of similar test between front pads.

If compression force between pads is adequate, perhaps the rear pads have become severly glazed or heat damaged and/or disc has oil or grease on it, either of which may impair needed friction between pads and disc.

Or just clean the disc (using acetone or brake cleaner) and install new pads, the softest organic pads available. If issue persists, then address caliper, master cylinder, brake pedal fitment and adjustment, etc.)

Good Luck!

I have recently new pads. No oil, grease, or glazing on them. The problem is that I have no pedal travel to speak of. I won't be able to get back to it until tomorrow, but I plan on taking the pads out and see how the caliper moves against the disc. It's as if the pads aren't free to move. I'll check for proper installation when I reinstall the pads.
Robert

i know it is repeat of info but i think the pads have glazed and if sanded hard with some 80 grit or a file to remove the surface to new material and try agian -you'll notice a big improvment....still does not explain the pedal ...i'd defintitly find movement wether you got drop the pedaql and see or whatever....good luck..least you got front brakes...peace

I had a similar problem last week. I noticed my brake pedal wasn't coming back up and my brake light was staying on. I ended up removing the right hand plate that holds the passenger pegs and brake mechanism and found the rod that the brake pedal is connected to was semi-seized up. I sprayed in some wd-40 and worked it loose. It was rusted in place so I cleaned the rust out and put in some anti-seize.

That was one of the first places I looked but everything was working as it should.
Thanks,
Robert

Think we're all missing something here. if w/ bleeder open lever travel allows normal bleeding and piston movement, would guess master cyl and brake pedal/line ok. new pads throw a red flag. would seperate caliper and carrior from wheel w/pads & tensioner bits in place and observe pad/piston motion when operated. a wild assed guess is pads are interfearing w/ something. take a look. luck g