05 Ninja 500r brake help

Hey guys! I really don't want to sign up for another forum site just to figure out this problem and I'm sure many of you know what to do.

I was checking out my front brakes because I keep hearing this grinding sound so I took of my caliper and one of the brake pads to see.
I then proceeded to press the brake lever to make the brake cylinders compress and found out that one is moving more than the other, so I pressed them all the way until they hit the other side.

Well now I can't get one of them back where it was! I think this is why I hear the grinding because one of them stays put while the other goes back.

How do I get this one cylinder back so I can put it back on the wheel?
Just some brake cleaner or something?

 

You sir, look like you need a caliper rebuild!

Your rear seal (lol) is causing a frozen piston condition.

If you didn't pull all the fluid out of your MC by pushing it out that far, you can clean the piston using brake cleaner or brake fluid and a toothbrush, and push it back in.

I would not recommend riding on that particular caliper until you've had it rebuilt/free up the stuck piston.

Brakes are the singularly most important thing on a bike, so take heed whenever there is a problem.

 

Also, a tip to free that piston up is to put a block between the moving piston and the fixed pad backing.

It will cause the other piston to move (unless it's REALLY stuck) and you can clean it appropriately as a temporary fix.

 

The one that moved out isn't the problem anyway. The one that stayed is seized and needs fixing. But if you are going to rebuild it might as well do both.

 

If you spray it on a toothbrush and clean the piston you're not going to be doing harm, fully soaking a caliper in cleaner, yes, you will be, I should have been more specific.

The seals won't let anything from the outside world, into your nice clean calipers (or at least they shouldn't as that would mean you have a failed seal, IE. no brakes)

 

Hey guys thank you!
Well both of them went all the way and was able to push that one in when I took the master cylinder cap off but the other one wont budge, so the one that is out in the picture is the problem.
Maybe I am confused how brakes actually work.

Does brake fluid from the master cylinder flow into the brake cylinders when the brake lever is pushed causing the cylinders to expand the brake pad against the wheel?

So I was able to push one cylinder up, does that mean all the brake fluid is behind that one cylinder that is extended making it hard to push back in?

 

You are indeed correct with how the brakes operate.

The fluid pressure created by squeezing the lever pushes the pistons out and the piston pushes the brake pads against the rotor.

There are seals surrounding the pistons that allow the pressure to be kept rather than weeping out around the seals and well... not being able to brake.

It looks like one of your seals has either shrunk, and is now sealing TOO tightly against the piston and not allowing it to move back freely (back just means not applying any pressure to the rotor) or your piston has become dirty and the grit is not being allowed past the seals. Even less likely is you have a blocked passage inside the calipers and is not allowing the fluid to pass back out of the caliper, this is likely NOT the case as you would have other problems in conjunction with the piston not returning. They do look fairly dirty, but the first two situations could be the case depending on how well the calipers were taken care of.

You can get the rebuild kits online for fairly cheap (as compared to a new caliper at least) and I would recommend staying with OEM parts; they're a little more expensive, but you do not want to cheap out on something so vital.

There are plenty of DIYs online if you are even a semi-competent mechanic, otherwise pop it back to the dealer and have them rebuild it. No harm either way and better safe than sorry if you're concerned about the systems integrity.