audi at humanspeakers.com
Tue Sep 7 21:40:55 EDT 2004
> After some enlightenment by listers and some careful listening under
> the hood, it definitely seems to be the vacuum pump. I should've
> known regular ol' lifter tick wouldn't make that kind of noise.
> That said, what are some of the pro and cons (if any) to removing the
> pushrod from the vacuum pump? Will it hinder braking performance at
What the vacuum pump gives you is braking boost when there is no intake
manifold vacuum - ie, when your right foot is down, too.
On my 82 coupe, which has no pump anyway, and on my 89 90Q, which lost
its pump years ago due to ugliness, if I experiment with braking while
revving at 3k or so, I get about 3 pumps before the pedal gets much stiffer.
In "normal" driving, there is no noticeable effect at all.
If your racing plans involve heel & toe braking, etc., you might want to
consider having it in there. You could, as you say, simply reinstall it
for race days. You could also try to fix it. I have read in these
pages that the clatter is due to oil building up on the other side of
the vacuum pump and that it can be cleaned out.
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