[s-cars] Brakes-S6, soft and spongy.. LONG

[Postupack, Jeff]

Awright!  I need help, have to break down and seek S List counsel.

Situation is 1995.5 S6 Brakes.

Problem= spongy brakes, the pedal vibrates (lightly) when depressed, the
brakes are not firm.
Can't leave the property.. 

Observations:  
1-Brake pedal was firm before I started mucking around!
Why did I fix it?  I'll never answer that question!~ frankly needed to
replace rear pads only.
2- I did NOT de-pressurize the bomb at the start, so I do not know the
start condition of the Bomb.
I 'later' read depressurizing the Bomb is advised.

3- Front brakes are OEM, in fact this entire S6 is Stock.

Changed the REAR pads only, used a caliper piston compressor to open the
gap, and reinstall.
I had to open the rear bleeder to move (open)  the pistons and drain
some brake fluid.

Bleeding: Built a pressure bleeder (thanks to Huw Powell, Tom Mullane)
and bled all 4 corners.

I searched the S car list archives, Audiworld, S-cars.org , www.20V.org,
and to my surprise I did not see a definitive brake bleed procedure for
the 
C4 chassis specifically. A few writeups mentioned techniques for ABS
equipped Audi's , tried to follow those ideas closely.

Yes, I read the Bentley,[ I own the paper manual set] not much there
frankly.. 

 but I gotta tell you, the bleeding procedures by Phil Payne and 20V.org
are much more comprehensive.


More Observations
1- The 1995.5 S6 does NOT have a brake proportioning valve located on
the Left side rear wheel area.
(My 1993 S4 DOES have this valve in the rear) 

2- My 1995.5 S6 does not have a bleeder at the Master Cylinder. (How do
I clear the air from the MC?)

Method: 

A: applied Super Blue with my Pressure bleeder at 10 PSI, Andrew made
sure no air bubbles entered the MC under pressure.

B: I bled the Right Rear, Left Rear, Right Front, Left Front calipers ,
the clutch slave cylinder first, in that order.

C: I started the engine and pressed the brake pedal, observed the pedal
'vibrated' slightly and then gradually moved forward, never reaching the
firm pedal I noticed when I  STARTED this whole process.

D: NOW I think to test the BOMB, shut off the engine and tested number
of pedal depresses. 
Counted 2, before the pedal got rock hard!

E: I pressure bled the system once again, more Super blue flowed into
the spend tank!

F: I started the engine and pressed the brake pedal, observed the pedal
'vibrated' slightly and then gradually moved forward, never reaching the
firm pedal I noticed when I  STARTED this whole process.

Same results. WTF!

I realize it is tough to diagnose via email, 
Is that BOMB dead?  It COULD have been on the verge of failure given 10
year life.
Is it possible I STILL have air in the system?

Whattaya think?

Posto