Rear brake problem zxr750

There are several problems. Your caliper could be stuck and that is a problem. You probably have a rubber brake hose that is clogged up internally and restricting the flow of fluid, a second problem.
The internal rubber hose can form flaps which close off the flow of fluid. You only have pressure in 1 direction so it is easier to have a stuck caliper because the fluid will trap in the caliper and refuse to return to the Master cylinder.
But this must really be blocked or the safety valve has shut off the diagonal lockout for the ABS. For safety when fluid pressure is lost, a valve shifts and tries to keep a front and a rear brake diagonally supplied with fluid.
What you need to try before giving up on the current project is bleed your brakes starting from the longest rear line and work your way forward with the last line being the shortest.
You may discover that you now have fluid bleeding from the problem caliper. If so, part of the problem was the safety valve killed the fluid flow. You still have a bad rubber line, and possibly a stuck caliper, but now you may have fluid flow.
If I were you, I would buy a rubber brake line and change it before bleeding the system. Then you can see if the caliper is working or not. Rubber lines are cheap compared to most parts.
By bleeding the lines as I recommend, you stand a chance of centering the safety valve and solving part of your problems. If a rear line diagonal to the problem front caliper is also dry, then the safety valve was tripped.
With the rubber brake line removed, you should be able to compress the problem caliper with ease; if not, it is stuck and should be replaced.
At this point, I should mention the ABS box. Pressure coming from the box can be measured as well as Master cylinder pressure going to the box. Hydraulic gauges would be necessary. It would be the final explanation to your problems should the easier solutions fail. Testing price versus component price should be considered.
You will restore fluid flow and be able to test your stuck caliper using what I gave you.

Replace caliper with old brake pads put 1 bolt in place to hold together while taking a large screwdriver and prying caliper piston so that it compresses piston & block wedge to rear of bracket it should make enough room to install on new brake pads, the other way is to use a large c clamp put 1/4 pice of wood in between c clamp and caliper so you don't damage or Mar the caliper also check YouTube.

Normally, just having a tire put on should not effect your brakes in any manner. However, I do not know what the people that changed the tire did. Usually when a brake caliper locks up, it's caused by air in the system. They may have taken the brake line loose from the caliper but it was not necessary and there's no way to prove it. Also, there is a small hole in the bottom of the master cylinder that allows the pressure to bleed off the caliper. If this hole is blocked, it will not allow all the pressure to bleed off properly. Another thing that could cause it is the rear rubber brake hose. If the people that changed the rear tire allowed the this rubber line to bend too sharply, it could have damaged the inner lining of the brake line. This will allow the brakes to be applied due to the high pressure but restrict the bleeding off of the pressure. I've seen this many times and this is my best guess as to the problem, damaged rubber brake line.

Good Luck
Steve

Did you bleed rear brakes also? Should do all 4 whenever bleeding brakes starting w/ right rear, left rear, right front then left front. Sounds like air in lines.

If you have two people.....press brake pedal...open bleeder screw then close, release brake...repeat until you hear no air bubbles. Fluid will comes out of bleeder. do not reuse. Brake fluid must be clean.
Do one brake at a time. You should feel normal pedal pressure when complete.
If you are by yourself, you can put tubing over the bleeder screw and insert into a small bottle to catch the fluid, and create a air tight seal. It is called a one man bleeder kit.
One other way, is to use a hand vaccum pump to **** to fluid through the lines.
Good Luck! It is easy as pie.

it sounds like the brake pipe is blocked up with dirt or somthing,,,take the brake pipe off the rear caliper and stamp on the foot brake peddle if no fluid comes out there is the problem,,,it may be an air lock or just a blockage like you may have twisted the pipe closed doing it up to tightly? or only using one spanner insted of two!!!! if you have closed the pipe up, it would be safer to replace the pipe,,, before it blows out on you! also when you do finaly get brake fludid to the rear caliper,, press the pistons right into the caliper before bleeding the alr out then finaly pump up the brakes,,, dont bleed the brakes to slowly or the air will run back up the pipe,,,,undo the bleed nippel put your finger over the end of it and pump the foot brake about once every second till all the air is out then nip up the nippel,i hope this helps you out

Start from right rear, then, left rear, right front, left front. Fill master cylinder. Have helper sit in car, have helper hold brake pedal down. open bleed screw. fluid and air comes out. close screw. release brake pedal. Continue until no air comes out. Move to next wheel. Keep an eye on master cylinder fluid level after each wheel.

There could be a couple reasons for this. First thing to check is your return spring, is it still there and attached properly? Next thing to check is your master cylinder pressure release. Loosen the bleed nipple on the rear caliper. Does the brake release now? If so, your master cylinder has some debris clogging the fluid return passageway. Remove and clean it. If the brake still does not release after opening the bleed nipple, at least one of your caliper pistons is binding. Remove the rear caliper and the brake pads. Now press the pedal and force the pistons out. Looses the bleed nipple and attempt to press the pistons back into place. They should move smoothly when you apply firm pressure. Clean the caliper thoroughly. If you have a rebuild kit for the caliper this is a good time to rebuild it. After cleaning, put it back together, bleed the brakes and test again. It is normal for disk brakes to drag SLIGHTLY on the rotor, but they should not stop a free spinning wheel in less than a coupld revolutions when spun by hand.