sbh tuned

<center><img src="http://pictureposter.audiworld.com/2255/s8_001.jpg"></center><p>upon startup of the vehicle, the brake pedal feels soft. Once the brakes are used and/or pumped a few times the brakes seem to feel normal again.

i was thinking that perhaps it was a bad master cylinder? any other thoughts? vehicle has 60k miles.

thanks guys

airbil

..Pauls house for several days of diagnosis
or bleed the brake lines or have them bled..and install new fluid. It's messy job for sure.
HTH YMMV

sbh tuned

to be honest i only drove the car around the block today. it is my fathers vehicle.. going in to the stealership on monday to be checked out.

where does paul live? does he have an S8 also?

beav

I've asked the stealer to fix it three times and they keep saying that it's normal. Pedal feel and braking is scary when backing out of the garage - then goes to normal by the time I get to the first stop sign.

If you get lucky and have a dealer that actually gives a damn, please let me know how they fixed it.

kevinr

Actually in many ways, his car is better than a stock S8....

tpierce

Does your brake light in the IC stay on a few seconds later than the other lights?
2 thoughts:
1-you are driving before the hydrolic pressure for the brake assist is up to pressure. There is an accumulator in the system that is supposed to comprensate for this, but may be getting old.
2-the brakes suck when cold.The could be why only the S8 guys (is it only the S8s?) see this, because of the differnt front brakes. Once warmed sligtly they are okay.

Just my thoughts.

PaulW

Maybe the resevoir is leaking down when the car is off. Don't really know the details of the system, but the vacuum resevoir is on the right hand side in the fender I believe.

Worth checking to see if it's leaking down when the car is off.

If not, you could move onto the next thing.

JimR

&lt;*ding!*&gt;

GDJT Allroad^2

behind the block. It has a check valve in it. On the '97 A8 it went bad. ... I'd assume there are similar vacuum lines on the S8. Replacing this firmed up the brakes some. It was also stupid expensive from the dealer for just a hose. It's a single molded piece that includes the check valve that runs from the master cylinder and then fits into a vacuum hose behind the block.

<img src="http://pictureposter.audiworld.com/55702/brake_vacuum_line1.jpg">
<img src="http://pictureposter.audiworld.com/55702/brake_vacuum_line2.jpg">

sbh tuned

do you have a p/n for that? i will check the junkyards.

thanks