Brake problems after rear disc upgrade

[HadesOmega]

I just finished doing a rear disc conversion on my 76 280Z. I think i used 240SX calipers, it was a while since I installed em and picked em from the yard. Then 240SX rotors and 81 Maxima caliper brackets.

 

I bled the the drivers side rear first which I heard is wrong but I bled that first and it seemed fine fluid would come out of it. I bled it with a vacuum pump also. Then when I went to do the passenger side all I would get is air maybe a little fluid didn't seem the same as the other side. Also the passenger side is the side I blew my wheel cylinder on so I assummed it would take a while to bleed all that air out of it. I even had someone help me bleed it the traditional way and doesn't seem to help either. Then i took it out for a drive and man the pedal hit the floors and barely grabs. to get it to grab more I have to really pump the brakes then I'll have enough pressure.

 

What do you think the problem is? I'm still running the stock size master cylinder I heard we're suppose to upgrade to a 15/16th size 280ZX master cylinder so it'll have enough volume to push the pistons. I'm thinking it could be my booster also O_o. I also heard we're suppose to get a 280ZX proportioning valve, where in the car can I grade one of those? My cousin tells me its built into the master cylinder in some cars.

[tonycharger72]

I remember with when i was bleeding my chargers brakes i had the same problem, turns out that the Master Cylinder needed new seals, from memory the MS was leaking where it connected to the brake booster, when you are bleeding the brakes get someone to stand near the MS and see if you see fluid leaking out anywhere - with mine it was quite obivous

[ezzzzzzz]

There are those that will voice desenting opinion but I'll post this anyhow. I first open the bleed screws (speed bleeders types), one at a time, and force fluid out of the system (via brake pedal) until the MC is empty. I'll even use low pressure air to move additional fluid up the the MC or disconnect the lines at the MC and blow air through the lines and opened bleed screws. An inline filter (like used for paint guns) works wonders to reduce moisture. I then use a pressure bleeder to force fluid up to the MC from the caliper/wheel cylinder until the MC reservoir is full again (you need to replace the speed bleeders with stock screws temporarily). Lastly, I bleed the calipers/wheel cylinders as normal. This ensures that most air has been removed from the lines and the MC is bled properly. This technique has never failed me. If I don't get brakes and there are no leaks or sticking calipers, I look at the MC as having failed. I also use silicone fluid (makes for a slightly spongy pedal). The argument is this pressurized fliud has air and moisture induced into it during the process. and that isn't good for the system. I'll agree to a point. Bleeding and replacing fluids is vital to longivity whether it's oil, tranny fluid or brake fluid. Most people don't do this...