[s-cars] Fwd: S6 Brake Master Cyl

[Steve Eiche]

Dennis,
The obvious is uneven brake distribution.   That could be air in the
system, a bypassing master cylinder (leading candidate in my book), or
messed up pads.  I don't think that the S6s have the old proportioning
valve in the rear circuit that caused problems in the 5ktqs.  Do you use
the parking brake and does it work smoothly?

So, he is what you know:
Bomb is good
Assist is good (if the pedal returns all the way back, you have good
assist and no hydraulic leaks, I would say that the booster is good)
No leaks in the brake hydaulics
Air in system??

Sure points the the master cylinder to me, but you may want to inspect
all of the pads for wear and the calipers and guides for binding.

BTW, I bought a Motive power bleeder with just about every adapter there
is (the one shops use).  If you want to borrow it any time, let me know.

Steve Eiche
Shade Tree Software, LLC
http://www.shadetreesoftware.com
seiche at shadetreesoftware.com
800.419.6896 ext. 902
303.940.2468



dgraber460 at aol.com wrote:
> First off, _thanks_ to all that responded. Too many to answer 
> individually so hopefully this will reach everyone. This list is so 
> great!
> Well - I was seriously depriving some village of its idiot! The light 
> issue is solved. Not the pedal issue - just the light. The brake fluid 
> reservoir level was right at the seam which is just slightly above the 
> "min' mark, which was enough to trigger the light. A jigger more brake 
> fluid and no more light while driving.
> The pedal behavior has now escalated to the anti-locks briefly coming 
> in at 10 mph on every stop, and the pedal is still softer than I would 
> call normal.. The anti-lock system works fine on ice and snow, and I 
> still get 44 pumps to hard pedal after shutdown. The hydraulic and 
> brake fluids are at or slightly above their respective marks both 
> running and stopped.
> Other than wheel sensors - what triggers the anti-lock system?
> TIA  
>
> Dennis Graber
> Denver, CO
>
>
> -----Original Message-----
> From: dgraber460 at aol.com
> To: bhowell at rmi.net; petergolledge at gmail.com; hackl911 at comcast.net; 
> seiche at shadetreesoftware.com; dlawson at ball.com; audionly at gmail.com
> Cc: s-car-list at audifans.com
> Sent: Wed, 14 Jan 2009 7:24 am
> Subject: S6 Brake Master Cyl
>
> Well here is the latest on my ongoing ’95 S6 brake saga.
> The pedal has been softer than should be for over a year. The brake 
> light has been a pest for years gradually staying on longer, but of 
> late has been staying and coming on even more frequently. The light 
> now comes on with any change in g-force – either forward 
> (acceleration), back (downshift), up, down, or side to side. This is 
> without any input from pedal or steering wheel. Potholes and jarring 
> do not trigger the light. The chassis has to actually change 
> direction, which leads me away from loose connections. Input from the 
> steering or brake will also trigger the light as well.  I have flushed 
> the system twice, replaced the bomb and pump, and the anti lock wheel 
> sensors – no change. The fluid level is above the reservoir marks at 
> rest and when running. I get 44 pumps to hard pedal after shutdown. 
> Lately on brake application it will give braking, vibrate slightly as 
> if the anti-lock kicked in, go farther down another ½” and continue to 
> brake. This is on completely dry road. The anti-lock system works to 
> spec on snow and ice.  
> My logic tells me it has to be the s ervo, but at $500-700, I would 
> like to be sure.
> TIA for any guidance/suggestions and BTDT.
>
>
> Dennis Graber
> Denver, CO
> 720-838-0558
>
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