[urq] [s-cars] S-Car Brake system conversion- Read- no more PS pumpintegration <question>

[LL - NY]

Having regularly autocrossed a venturi vacuum assisted vehicle (2005 Saab
9-2X, nee WRX) and having learned effective left foot braking from my
previous A2 GTi autocrosser, I can vouch for vacuum assists and turbos isn't
a great combination in track/autocross conditions (there's even less
recovery time for autocrossing). If I go into red-mist mode, and start left
footing on course, I can loose assist/ABS within 20 - 30 secs on course. On
the Saabaru, at least, if I pull the ABS fuse before a run, I can man-brake
the thing when the assist fails, but it's a pretty poor compromise. Not sure
if I'd want that to happen on the street, where the speeds are higher, and
in spite of my opinion that the Saabaru could also be called Miss Piggy, the
extra mass of our Miss Piggy's and no assist is NOT, IMHO a pretty picture.

LL - NY

On Sun, Mar 15, 2009 at 10:18 AM, <dgraber460 at aol.com> wrote:

> I have an UR S6 with brake issues as well, so I can empathize with those
> feelings! My car is briefly activating the anti-locks on every stop as the
> speedo crosses 10 MPH on decel.
> In the FWIW department, I have switched my URQ over to the vacuum system
> from a CGT, and it works fine for daily driver duty. However, I have tracked
> the car twice since and found that 4 laps on a small tight course is all I
> get from the vacuum system. In the? fifth lap on both courses the brakes
> went rock hard.?Still functional enough to keep me out of trouble, but the
> assist was gone. Pulled into the pits and let it set for a few minutes and
> all went back to normal. Four more laps and repeat.
> In the past when I have tracked a car with regular brake fluid (not
> SuprBlue) I have encountered boiling brake fluid which required a much
> longer recovery time, and felt much more disconcerting on use. The brakes
> would almost go away completely.
> I'm definitely not suggesting you take either option and modify your brakes
> in any way. That is totally your responsibility, but thought this
> information might be of interest.?
>
>
> Dennis Graber
> Denver, CO
> 720-838-0558
>
>
> -----Original Message-----
> From: John Cody Forbes <cody at 5000tq.com>
> To: vinnieb2 at yahoo.com; s-car-list at audifans.com
> Sent: Sat, 14 Mar 2009 9:54 pm
> Subject: Re: [s-cars] S-Car Brake system conversion- Read- no more PS
> pumpintegration <question>
>
>
>
> Without GOOD engineering a vacuum assisted system is not exactly a good
> idea
> on a turbocharged car which is exactly why Audi went to hydraulic brake
> boosters anyways. The '95 A6 system would likely not be suitable. It could
> likely be made to work, but I don't think it's worth the risk of a failure
> at the wrong time. The modern cars use a venturi vacuum pump to create
> vacuum for the brakes even when on boost, but these venturi's fail (get
> clogged) on a somewhat regular basis.
>
> -Cody Forbes
>
> brian bilotti wrote:
> > S-Heads,
> >
> > Anybody done this conversion? I'm sick of having brake issues with
> > the PS pump. My mechanic says that the A6 has a vac assisted set up
> > that eliminates the need for PS pump integration.
> >
> > The need for some off the shelf parts and a check valve is all I
> > need.... I'm told.
> >
> > ANY info would be great!
> >
> > Thanks
> >
> > Brian
> >
> >
> >
> > _______________________________________________
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>
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