This is a little long and I apologize but I have tried so many remedies that i can save your breath with some suggesstions that may sound like the fix, but I have tried most of them.

Started with GS rear end drum brakes. I swapped the front GSL-SE calipers and rotors etc... And dropped the car off to get some exhaust work done. Brakes worked fine.

Got car back and swapped out a GSL-SE rear end plus calipers and rotors pads etc... I did not receive the lines for it, so I made some with line from auto part store and a T fitting. No pedal. It is quite squishy but can be pumped up to pressurize and held, when releiced the pressure is gone. Indicates a leak it seems but I could not find one. I basically got the car over to park it by continuosly keep pumping pedal to maintain pressure.

I took my caliper and the old lines (from the rear hard line back) into a speed shop and and got some hard line and SS line to rerun all the line thinking there was a leak.
No fix

I then went and got a Master Cylinder, no fix. I took one of the old rubber lines of the back and JB welded on of the ends close. I put that on the back hard line and my pedal was back.
This leads me to beleive that the new master is okay.

I ordered new calipers, rotors and pads and just installed them on the rear and bleeded the system. Same issue.
I have now stooped to bypassing the porportioning valve with 2 rubber lines to see what happens. Well the pedal seems better but still not correct. The pedal is now only 1-2 pumps away from being pressurized.
It is also weird that when I pump the lines up and let it sit the master seems to get higher in fluid, if that makes sense?

Does the cap have to be on for pressure? doubt it.

Basically this isn't a question that I hit a hurdle and I am asking. I have working on this for a MONTH now and can't get it!

PLEASE HELP ME!!!

 

when you bleed the brakes is there air that comes out of the lines every time?

 

No, only when I end up removing a line or something that puts air in. Totally solid all the time. I even switched to speed bleeders to make sure air never went back in

 

so u have a brand new master? if so i can only think that there might be a clog in the line? check front calipers too?

i personally love to use pressure bleeders.

 

I think you have air your master cylinder - they can be easy sometimes, hard others.
I usually fill the inside piston area with fluid when I rebuild them, other people have a method for bench bleed which I have not ever done. I think you want to see fluid coming out of this on all ports when pushing in, I bet if you check, you are getting air.
Be careful not to do this on the car - brake fluid will dissolve your paint.

 

What master cyl are you using? a master for drum brakes prob wont move as much fluid as a master for disk brakes due to the volume of fluid in a caliper. if you replace the master with the correct one make sure you bleed it out before installing it on the car

 

well, i bench bled the master before putting it on. What should I do? take it off and rebleed it?
I cna't remember for the life of me which master I bought to replace? If it was a for 12a or GSL. Ill look into that

 

Did you get the gslse proportioning valve as well?

 

no, but I currently have that bypassed

 

Hey man! I just had my clutch master fail on me a week ago. When I tried to bleed it the fluid would rise up instead of going down like you said. I got a new one and works perfectly now. I think you still got a bad brake master. Just my thoughts. Hope you get it worked out soon.

 

I found out today when I replaced my master I got another 12a one. I couldn't source a GSL-SE one today, so I will order one and hope to get it by friday to try this again next weekend!

thanks for everyones response. If there are more thoughts let me know and I will try them

 

IIRC, All master is the same size for the SE and 12A

 

^^word. i would try to bench bleed the master just 1 more time for safe measures.

 

GSL and GSL-SE have a 7/8" bore. The 2nd gen uses the same internals, but the outside has the lines in different places.

The S and GS master cylinder has a 13/16" bore. It also has a pressure retaining disk for the rear.

 

correct. drum masters are 13/16 while disk masters are 14/16.

 

Ya, I knew there was definantly SOME difference because its a totally different part number and everything at these places if you have 4 wheel disk or not.

So basically if I order this other master, it will or will not hook up? Is there something else I would need to buy?

 

I'm confused, shouldn't the one he has now work fine guys? I got a 13b in my gsl but its still got the original 12a brake master.

 

The Disk and Drum master have the fittings in all the same places. The two differences are the bore size and the drum cylinder has a check valve where the rear fitting screws in.

I had a similar problem switching to disks, but it turned out my new master cylinder caused my front calipers to fail.

 

Your GSL would have come with the GSL/GSL-SE disk brake master, not the S/GS drum master.

 

Oh ok, I see now. Thanks for clearing that up. My bad.

 

perfect. I am ordering a GSL one as the one I have now is either broken or air in it. Id rather get a NEW one and get this done in 1 shot next weekend!

 

Some people just got to stop posting inaccurate information that you cannot mix parts...meaning GSL rear end (disc to disc) with non-GSL proportioning valve and master cylinder. Just my $0.02.

 

What do you mean by this? You can use the S/GS master with a disk brake setup, but you would have to remove the check disk from the S/GS master to eliminate the small amount of constant pressure to the rear lines (to overcome the drum springs) that can cause dragging in the rear.

As for the proportioning bypass valve, I don't know. I do know that they are different part numbers and stampings on the steel for the disk and drum versions.

 

Check disk, you mean the little white thing in the actual brake fluid container?

 

No, that is a floating magnet for the brake fluid sensor. If you look at the rear outlet for a drum master, there is a big nut. Unscrew this and there is a little plastic dish and a spring. This is the check disk that keeps a constant pressure on the rear lines.