Asking for opinions

[urq]

When I read your symptoms they sound an awful lot like a bad bomb on a
hydraulic assist system.  I've never had a need to work on a vacuum assisted
system, is there any way to measure vacuum inside the booster?  At the very
least I'd hook a vacuum gauge where the vacuum line attaches and see what
happens to the system pressure as you apply pressure on the brake pedal.  I
guess the thing that you'd expect with the hydraulic analogue is that if you
stabbed the pedal and held it that the assist would pick up after a while
... have you observed anything like this?  

Of course since I've never experienced it myself I can't say, but it sure
seems to me that not being able to apply full braking immediately in an
emergency situation creates a safety issue ...

Steve Buchholz

-----Original Message-----
Guys,

I thought I'd put this out and see what others think.  The subject is my
1980 Audi 5000S (type 43).  Its always had this little quirk where braking
power seems inverse to applied force.  If you stomp on the brakes, you get
very little assist.  However, if you step on the brake pedal and apply
increasing force, you get all the braking you desire.  

When I first got this car (1986, my first Audi years ago!) it had this
symptom.  It had the Teves calipers on it, so I upgraded to the Girling G54
calipers and 280MM rotor from the T5000 turbos of that era.  I also have the
rear disc brakes from the same.  Made no difference in the brake function.

My thought is that its something to do with the vacuum booster.  The
standard test is to depress the pedal slightly and start the engine and the
pedal will pull in as vacuum builds and it does that.  But I never been
completely happy with this syndrome and was wondering if its worth it to
replace the vacuum booster.

TIA,

Tony