[urq] vacuum brake booster conversion

Ben Howell bhowell at rmi.net
Mon Apr 6 07:56:16 PDT 2009

You want your lines to match the MC. So, no matter what lines go where on the original MC, you need the lines to match where they would go on a 200.

In the case of the 200 MC, you want the two front ports to go to the two front Calipers. You will use one of the rear ports to feed the rear calipers. If there isn’t on there already, you’ll just use a 10x1.00mm brake bleeder screw to plug the other rear port. It’s also goo for bleeding the MC in the car as opposed to bench bleeding.

The line going to the right front wheel will NOT be long enough to reach the MC as it is originally designed to go to the prop valve mounted below the MC and not all the way to the MC. On any junkyard 200/100/V8/S4/S6/5000, there is a 10x1.00mm coupler that is mounted down below the MC, almost at the frame rail on the driver’s side. VERY handy to have for the conversion. Alternatively, they are only about $11 at the dealer for a new one.

As for a Prop Valve, I would think you would want to plumb that bad boy into the line going to the rear calipers. In the past , I have had good success buying a prop valve with XXXX thread and using a 10x1.00mm tap in the existing threaded ports so I can use stock Audi lines.

With THAT said, the 200/V8 MC is internally proportioned (e.g. the front chamber moves more fluid that the rear chamber) to some extent and then it uses the prop valve mounted under the rear of the car for “trim”. So, I have had great success (read: no rear brake lock-up) just mounting that MC with no prop valve. YMMV though.


-----Original Message-----
>From: Mike Sylvester <mike at urq20v.com>
>Sent: Apr 6, 2009 10:21 AM
>To: Ben Howell <bhowell at rmi.net>, craigcook at rogers.com, urq list <urq at audifans.com>
>Subject: RE: [urq] vacuum brake booster conversion
>Where is a good place to find the metric fittings?
>Most places that I've seen only sell the English sizes.
>When using the 4 port MC and the Willwood proportioning valve, 
>I assume that the front brakes are plumbed into the front 2 ports,
>the rear goes into one rear port and the other rear port is plugged.

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