# 16V Scirocco rear disk proportioning valve ID



## suburbangeorge (Apr 24, 2004)

Does anyone know how to identify which valves are which on VW's inline rear brake proportioning valves? I am including two Emails that I sent to another member. 
I have two loose sets of these plus one set installed on my car. None of them has the kind of part number you expect with VW. I cant read the ones installed on my car too well but all three sets have different numbers. Each of the loose ones is a cylinder aprox. 7/8" in diameter and aprox 1-7/8" long. In the top end is a female threaded hole for the brake line to screw into. At the bottom end is the same thread, male, to screw into the master cylinder (you can screw these things into each other). On the end with the male thread, are two flats on opposite sides of the cylinder so you can tighten it with a wrench. If you look at either of these flats with the male thread pointing up, you can read a number 3 then an arrow pointing away from the male thread (down in this position) then the numbers 3.5. If you hold with the male end down you can read the number 1 on the side of the cylinder about 3/4" from the end with the female thread. Below that on each is a series of numbers which can be read with the cylinder held sideways (female to the left male to the right). One pair has 0865G, the other pair has 293G4. I can't read the pair in my car but it starts different still.
I talked with VW today and they have differnt part #s for the valves for 8V and 16V Sciroccos. I got these from someone else not directly from a car. I am reluctant to sell these without knowing that they are the right parts. If I remember my front disk-rear drum set up on my Chevy truck, the rear drum valves would give too little pressure to the rears to operate disk brakes. Drum brakes are self energizing and require less force to opperate. So the valve sends limited pressure to the rears so that they don't lock up while the fronts are working. I guess this also the job of the 16V valves, but they do not limit the pressure as much.
It seems to me, although I haven't taken one apart yet, that the difference lies in the strength of a spring inside, or perhaps the size of a port. 
Any help or info on these would be greatly appreciated. 
















_Modified by suburbangeorge at 4:10 PM 5-17-2005_

_Modified by suburbangeorge at 4:13 PM 5-17-2005_

_Modified by suburbangeorge at 4:13 PM 5-17-2005_

_Modified by suburbangeorge at **** PM 5-17-2005_

_Modified by suburbangeorge at 4:22 PM 5-17-2005_


_Modified by suburbangeorge at 4:23 PM 5-17-2005_


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## Racer_X (Jul 14, 2002)

There's no easy way to tell them apart. 
The drum brake version has internal differences and two measurable differences in operation. The drum brakes use a different cutoff pressure, and the drum brake combination valves hold residual pressure to the rear brake lines. Drum brakes need residual pressure or the return springs will pull the shoes all the way in and squeeze too much fluid out of the rear wheel cylinders. With the VW self adjuster, this doesn't cause as big a problem as with other designs. Lack of residual pressure will make the pedal travel about half way to the floor before the brakes engage. 
Unfortunately, the residual pressure springs are the first thing to fail in older drum brake combination valves, so a lack of residual pressure either means you have the 16V valve or you have the 8V valve with a failed residual pressure section.


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