I re placed the master cylender and now i got no brakes in the back at all

the hydrolic cylender might be out of brake fluid. by the master cylender you should have a small jug that should have brake fluid. if empty you got a leak. if full you will need a new clutch.

You run a line clamp test. All you need is 4 clamp tools to block off all brake hoses with light pressure. Push on brake peddle if it's hard back off and push slow and light. If stays hard master cylinder is good. Hold pressure and have someone remove. The clamps

sounds to me that your power booster is not holding pressure

did you bench bleed the master cylender before installation?

you will need another person with you. take the cap off of the master cylender, and make sure it is full of fluid. start at the wheel farthest away from the master cylender. so the back passengers side, have your partner pump the brakes about 10 times and hold pressure against the brake. ( Tell them not to let off until you tell them.) loosen the bleeder, fluid and air will squirt out, tighten bleeder screw back up, ( they can now let off of the pedal). do it over a couple or three times until you get a steady streem of fluid with no air. then go to the drivers side back, then passengers front, and end up at drivers front. Keep a check on the master cylender that it doesnt get empty, keep fluid in it or you will need to start over again.. hope i explained this good enough for you to understand.. whatever you do make sure your partner knows not to let off of the brake petal, until you have the bleed screw tight, and tell them to let off.

You 're brake master cylender has failed.
How to change it.

Use a flare wrench and remove the two brake lines.
Then remove the the two nuts that hold it to the fire wall.
Then remove.
Then remove the master cylinder reservoir because your
going to have to put it on the new one.
Drain out any brake fluid from it.
In stall the reservoir on the new master cylinder.
Now you'll have to prime the new master cylinder.
Put the master cylinder in a vise and put brake fluid into it.
Now place your fingers over the two holes that the brake line go into.
Use a large phillips screw driver and push the piston in and out about 10 times.
But, do it slowly. make shore to keep your fingers over the brake line holes. .
Now install it back in.
Remember to bleed your brake system when your done.
Hope this helps give feedback and good luck FixYa

Brakes may be worn out and locking up. Take car to a brake shop but ask him first is there anything you can do to fix this. Don't drive without brakes.

You might have a leak in one of your brake lines i would look at all of the lines for a leak look at the brake drums for fluid driping out of the bottom if you dont find a leak it may be time for a brake job . a soft peddel means you have air in your system.From a leak or wore out pads or shoes or a leaking wheel cylender from wore out rear shoes . watch your master cylender to see if its low on fluid.

A classic example of a failing master cylinder is the brake pedal fading(going to the floor) while sitting in traffic,i.e. at a stop light. Brakes are nothing to second guess though.Let a mechanic make the diagnosis.

No diagram you must look under and find the leaky one.Fill up master cylender get a drain pan to put under car for when leak starts squirting out save a mess also DOT 3 BRAKE FLUID ONLY!.use a yellow crayon to mark it so if leak is under seat area mark it then follow it to the wheel it goes marking every couple inches.Now go back and work you way to the other end that goes to master cylender! you will have now found your leaky line.