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

[Louis-Alain Richard]

Well, the stock diesel Renaults I worked on in 2005 had this setup : huge
vacuum assist, and a small electric pump. And the most funny fact about this
is the pump is exactly the same Bosch unit that is used by Audi for the
cruise control on my urQuattro, and plenty of other models. Plenty of them
at the scrapyard for you to test. 

 

Never raced the Megane or the Laguna, though. 

 

Louis-Alain

 

 

-----Message d'origine-----
De : urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] De la part
de urq
Envoyé : 15 mars 2009 13:50
À : urq at audifans.com
Objet : Re: [urq] [s-cars] S-Car Brake system conversion- Read- no more
PSpumpintegration <question>

 

I believe some manufacturers have an electric vacuum pump in the system ...

a friend of mine had an old Celica Supra Turbo and that is what it used for

ensuring brake boost was available.  You'd need to have some idea of how

much capacity was needed per brake application, and how many applications

per minute to scope the pump flow rate.  

 

Another option would be to add vacuum reservoirs to the system.

 

Steve B

San Jose, CA (USA)

 

-----Original Message-----

 

Interesting but not surprising. I wonder if something could be done on the

order of the old 4kq assist pump (maybe additional electric-driven vacuum

pump). The 4kq system, for those that recall, had a vacuum assist pump

driven by the camshaft. Not doable directly, of course. But that's

essentially what you need -- a vacuum assist helper. 

 

 

Ingo Rautenberg

 

-----Original Message-----

 

 

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

 

 

-----Original Message-----

 

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