Help needed for t-piece

[Ti Kan]

Hi all,

In trying to plumb in an idle-boost valve for my 4000's A/C system, I
am in need of a T-piece that's fits an 1/2" I.D. rubber hose on both
"straight" ends, and the tee-end would fit an 5/16" hose, something
like this (use fixed width font to view this ASCII art correctly):

           +-------+
     1/2"  |       |  1/2"
(or 13mm)  +--+ +--+  (or 13mm)
              | |
              +-+
              5/16"
            (or 8mm)

I need two pieces of this gizmo.  I plan to cut the existing 13mm I.D.
hoses for the CIS auxiliary air regulator, put in the tee, and
use the 5/16" end to run hoses to the idle boost valve (which has
8mm hose barbs).

Looking through the family album I found something that looks like what
I need (part # 049 103 693) but this part has a restriction built into
one of the 13mm ends (for crankcase ventilation) which I don't want.

I searched many the auto parts stores and hardware stores locally and
even thought about making one using air and plumbing fittings, but came
up empty.  I don't want to use too many big and heavy metal adapters
and couplings.  Pep Boys and Kragen have something that looks right
(Help! brand heater hose tee for Ford cars) but the sizes are too big.
NAPA has a t that's 1/2" on all three sides, but there does not appear
to be anothing that could reduce a 1/2" to a 5/16".

Any idea how I might achieve this?  Is there another VW/Audi part
that is what I describe?  Or perhaps a part from another car manufacturer?
Wishful thinking, but maybe one of you would have a couple of these things
that you would be willing to part with?

Thanks in advance,

-Ti
01 S4 2.7 biturbo quattro
84 5000S 2.1 turbo
80 4000 2.0
-- 
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Research Laboratories, Sunnyvale, CA. USA
  ///    ti at amb.org
 //////  http://www.amb.org/ti/
///