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

[Tom Green]

You probably just need to get the rear caliper pistons adjusted  
closer to the rotors.  If you did
the front like this too, the pedal would probably hit the floor at  
first.  Just run an autocross
course in reverse and it should firm up.  Oh, I forgot to ask, How's  
the hand brake ?  And the
clutch ?  And warning lights  ?   Give the bomb a check after you get  
the brakes adjusted.

Tom

> Date: Fri, 21 Apr 2006 11:50:21 -0400
> From: "Postupack, Jeff" <Jeff.Postupack at analog.com>
> Subject: [s-cars] Brakes-S6, soft and spongy.. LONG
> To: <s-car-list at audifans.com>
> Message-ID:
> 	<8FDC0F9BE1F91D44BE964AA54AAA67B61C09CECE at wilmexm3.ad.analog.com>
> Content-Type: text/plain;	charset="us-ascii"
>
>
>
> 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
>
>
>
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> End of S-CAR-List Digest, Vol 30, Issue 63
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