No Brakes!

[belchfire]

"81 caddy. Installed '85 audi GT calipers & '96 jetta discs. Stock MC & rear drums. Worked well for 4 years. Down for a month for engine rebuild & when I got it going I had no brakes. Figured that the master died after 31 years so I changed it to an '88 jetta 4-disc unit. (rear discs will come in a minute). The old booster has a different bolt pattern so the MC doesn't fit. I just happen to have another that came from an unknown year but it worked. I had to modify the push rod attachment, a minor annoyance. The vehicle stopped but the pedal was quite low. I figured that that was because the shoes had to expand to the drums where as discs don't so it was OK for the time being. The IP needed rebuilding so it was down for another month. Why not install rear discs? I had these from an '85 golf GTI and they bolted right up. When I pulled the MC @ the junk yard, It appeared that there was no P-valve to the rear. I removed the '81 valve and joined the lines with a butt connector. It appeared that the '81 had some sort of weird diagonal brake system but the jetta did not with the front two coming from the front and the back the back. I bent the lines around and hooked them up thusly. The E-brake mechanism was froze on one so I bought a rebuilt. Jury rigged the cables and off I go. Now I've got no brakes.  Bled a gallon of DOT 4 through the system. Cranked the rear pistons so that the E-brake lever actuates about 1/2 way down- nothing. Bought a new MC ('88 jetta) no improvement. I can get some braking if I punch it to the firewall but only some. I thought that the push rod might be too short so I made a 1/2" long spacer but when I went to bolt it back up, it was too long by---1/2". I also can't pump up the MC. I've never had that happen before. What am I missing?

[CRSMP5]

1 big paragraph sucks ass...

2 things....

rear drums take less fluid then disks.. why master upgrade.. if low with drums will be lower with disks...

you better find some prop valves... mk2 is mounted on rear beam at flex joint/spring loaded for weight... many years ago, 93, i did my rear disk conversion on my coupe... with stock spring loaded mk1 german prop it woul turn rear rotors blue and lock up before the fronts... i put 16v rocco in line pro valves in it... which is what you seek.. no valves your in for a ohhh *** my ass is passing by...

you had to screw something up on your master upgrade... me i kept my stock mk1 master set up.. pedal is lower, but braking force is better... aka outbrakes a 16v rocco... just not as high a pedal..

so start over on the master set up... id look for a later cabby/rocco booster and pedals... so it bolts in with no mods

see how big paragrah sux...

[R.O.R-2.0]

not all mk2s have the prop valves on the rear beam..

they have them right on the master cylinder too.. like my 86 Golf does..

[CRSMP5]

ok non westy mk2... LOL.. been too long since i saw a westy mk2...

[R.O.R-2.0]

ok non westy mk2... LOL.. been too long since i saw a westy mk2...

my GTI was westy. rear prop valve..

my Golf is also a westy, and has front prop valves..

[belchfire]

Fair enough on the prop valve and I was perplexed that I saw none on  the MC donor car. I surely would have swiped that too if it had been there. But that's down the road after I get them to actually work.
  I went with the new MC because a) there's no residual pressure valve as is needed with drums and b) The difference in piston diameters should achieve a certain amount of proportionality and c) 22mm is bigger than 21 and thus should supply sufficient volume to the calipers.
  I figured that if I used a 4 wheel disc master on a 4 wheel set-up, then it should work fine. Last time I checked, a 16v MC was $250 w/core. This one was $48 new. Is there really an internal design difference?
Probably hit the junk yard tomorrow for better ideas.
  Sorry about the paragraph. I was unaware that this website had a grammar police. Just trying to get all of the information down. It was late, I was tired and obviously frustrated.

[CRSMP5]

i can care less on grammer... not my grip.. my gripe... whole bunchs of words all grouped together.. hard to read.. some people have difficulties moving onto the next line... or skipping a line.. not like a book where you can use finger to point where you are.. normally id skip a original post like yours.. but i have knowledge on this.. as i did it way before interwebz..

prop valve has to be from rear disk car.. more restricted then drum.. german mk1 has the check valves where westy goofy prop valve is... easy to remove.. i put my 16v rocco ones in their place.. originally use couplers to take them out.. till i relized the rear disks worked too well..

sadly you have something set wrong on the push rod.. my guess is your modded pedel attachment.. but no clue.. cannot see the booster/master connection as a issue if they were matched parts... so your mod is whats left..

[belchfire]

I did some extreme bleeding by taking the caliper off, pumping it up, then compressing it with a C clamp then bleeding it.  In the unmounted configuration, I got a significant amount of air out. Then it dawned on me that the bleed screw was not at the highest point of the cylinder. The reason being that somehow in the 3 years of the parts lying around the shop and having no schematics or memory to go on, the left and right got switched. I put them in their proper home (the E-brake cables fit much nicer) and they work much better. Still not good enough to determine whether or not I need a P-valve but if I do, I'm thinking that one of the load sensing ones might be the trick. Once the sweet spot is found, then just wire the lever in place and good to go.