Bug master cylinder: Residual Pressure Valves?

Well, the brakes went soft on the 'ol 69 bug, and a puddle appeared under
the master cylinder, so it was time for a new one. Went to the FLAPS and
got a new German FTE/FAG M/C. It looked quite similar to the original (yes,
it was the 35 year old original, complete with a blob of body sealant!)
except that it lacked the mechanical warning circuit switch hole. Not a
problem, since the warning light circuit didn't work anyway!

Anyway, on to the question: The old M/C had three fittings screwed into it.
The brake lines screwed into these fittings. I believe that these fittings
were called "Residual pressure valves". The new M/C did not accept these
valves, but were threaded for the brake lines to be screwed directly into
the M/C.

The brakes bled fine and seem to work better than ever, but I'm still
bothered by the residual pressure valves. Is that function built into the
newer casting, or was it not needed in the first place?

Any brake gurus out there with info?

George

wrote:
> Well, the brakes went soft on the 'ol 69 bug, and a puddle appeared
> under the master cylinder, so it was time for a new one. Went to the
> FLAPS and got a new German FTE/FAG M/C. It looked quite similar to
> the original (yes, it was the 35 year old original, complete with a
> blob of body sealant!) except that it lacked the mechanical warning
> circuit switch hole. Not a problem, since the warning light circuit
> didn't work anyway!
>
> Anyway, on to the question: The old M/C had three fittings screwed
> into it. The brake lines screwed into these fittings. I believe that
> these fittings were called "Residual pressure valves". The new M/C
> did not accept these valves, but were threaded for the brake lines to
> be screwed directly into the M/C.
>
> The brakes bled fine and seem to work better than ever, but I'm still
> bothered by the residual pressure valves. Is that function built
> into the newer casting, or was it not needed in the first place?
>
> Any brake gurus out there with info?
>
> George

When i replaced mine on a 69 buggy, the brake lines screwed into the master cylinder. It look like this
one,http://www2.cip1.com/ProductDetails....1%2D0 15%2DBD, but i got it from my flaps. Neither
my 69 or my wifes 68 have any kind of external Residual pressure valves.

David

wrote:
>
> Well, the brakes went soft on the 'ol 69 bug, and a puddle appeared under
> the master cylinder, so it was time for a new one. Went to the FLAPS and
> got a new German FTE/FAG M/C. It looked quite similar to the original (yes,
> it was the 35 year old original, complete with a blob of body sealant!)
> except that it lacked the mechanical warning circuit switch hole. Not a
> problem, since the warning light circuit didn't work anyway!
>
> Anyway, on to the question: The old M/C had three fittings screwed into it.
> The brake lines screwed into these fittings. I believe that these fittings
> were called "Residual pressure valves". The new M/C did not accept these
> valves, but were threaded for the brake lines to be screwed directly into
> the M/C.
>
> The brakes bled fine and seem to work better than ever, but I'm still
> bothered by the residual pressure valves. Is that function built into the
> newer casting, or was it not needed in the first place?
>
> Any brake gurus out there with info?
>
> George

The masters that accept residual valves are no longer available new, I
believe. Which is kinda sad.
The non-valve type works ok but you may want to keep the shoes adjusted
so close to the shoes that they drag approximately 1/2 way through a
full turn of the wheel. (For some reason the drums are never true)

Jan

Jan

wrote:
> Well, the brakes went soft on the 'ol 69 bug, and a puddle appeared under
> the master cylinder, so it was time for a new one. Went to the FLAPS and
> got a new German FTE/FAG M/C. It looked quite similar to the original (yes,
> it was the 35 year old original, complete with a blob of body sealant!)
> except that it lacked the mechanical warning circuit switch hole. Not a
> problem, since the warning light circuit didn't work anyway!
>
> Anyway, on to the question: The old M/C had three fittings screwed into it.
> The brake lines screwed into these fittings. I believe that these fittings
> were called "Residual pressure valves". The new M/C did not accept these
> valves, but were threaded for the brake lines to be screwed directly into
> the M/C.
>
> The brakes bled fine and seem to work better than ever, but I'm still
> bothered by the residual pressure valves. Is that function built into the
> newer casting, or was it not needed in the first place?

Yes, it's built into the new "universal" M/C.

"David" > wrote in message
...
> wrote:
> > Well, the brakes went soft on the 'ol 69 bug, and a puddle appeared
> > under the master cylinder, so it was time for a new one. Went to the
> > FLAPS and got a new German FTE/FAG M/C. It looked quite similar to
> > the original (yes, it was the 35 year old original, complete with a
> > blob of body sealant!) except that it lacked the mechanical warning
> > circuit switch hole. Not a problem, since the warning light circuit
> > didn't work anyway!
> >
> > Anyway, on to the question: The old M/C had three fittings screwed
> > into it. The brake lines screwed into these fittings. I believe that
> > these fittings were called "Residual pressure valves". The new M/C
> > did not accept these valves, but were threaded for the brake lines to
> > be screwed directly into the M/C.
> >
> > The brakes bled fine and seem to work better than ever, but I'm still
> > bothered by the residual pressure valves. Is that function built
> > into the newer casting, or was it not needed in the first place?
> >
> > Any brake gurus out there with info?
> >
> > George
>
> When i replaced mine on a 69 buggy, the brake lines screwed into the
master cylinder. It look like this
>
one,http://www2.cip1.com/ProductDetails....3%2D611%2D0 1
5%2DBD, but i got it from my flaps. Neither
> my 69 or my wifes 68 have any kind of external Residual pressure valves.

My new M/C looks like this one:

http://www2.cip1.com/ProductDetails....2D0 15%2DBDGR

Which, I believe is the German version of the one you cited. The only
external difference is the bleed screw on top.

Another response indicated that the function was incorporated into the
casting in the later part. I certainly can't fault its fit or function,
both are fine.

George

On Sun, 13 Feb 2005 21:59:53 -0800 > wrote:

>Well, the brakes went soft on the 'ol 69 bug, and a puddle appeared under
>the master cylinder, so it was time for a new one. Went to the FLAPS and
>got a new German FTE/FAG M/C. It looked quite similar to the original (yes,
>it was the 35 year old original, complete with a blob of body sealant!)
>except that it lacked the mechanical warning circuit switch hole. Not a
>problem, since the warning light circuit didn't work anyway!

If you want to make the warning light work again, you can wire this MC
the same as the later MCs and get that function back. The later wiring
scheme is much better and avoids the awful system introduced in '68.
What's truly amazing is that it took VW 2 whole years to figure out
that mistake.

OTOH, the whole system is pretty much worthless since you've already
panic'd by the time the light goes on.

>Anyway, on to the question: The old M/C had three fittings screwed into it.
>The brake lines screwed into these fittings. I believe that these fittings
>were called "Residual pressure valves". The new M/C did not accept these
>valves, but were threaded for the brake lines to be screwed directly into
>the M/C.
>
>The brakes bled fine and seem to work better than ever, but I'm still
>bothered by the residual pressure valves. Is that function built into the
>newer casting, or was it not needed in the first place?

I have never understood any good reason for this. It MAY have helped
keep the brakes working reasonably even if they were left unadjusted
for years. but I'm not even sure of that. The system works just fine
without them, and they are no longer used. There's nothing inside your
new MC that replaces them.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

> wrote in message ...
>
> Another response indicated that the function was incorporated into the
> casting in the later part. I certainly can't fault its fit or function,
> both are fine.
>
> George

VW discontinued the residual pressure valves starting with the 73 model
year. Instead the drillings in the brake line ports were sized to the
smaller spec of the disc brake master cylinder. This is why disc brake
conversions should never utilize the pre 73 drum master cylinders.