2WD Low Via Manually Controlled Axle Disconnect

Took me most of the day but I finally got it done.  By
putting a couple of valves in the front axle vacuum lines I
can connect/disconnect the front axle (almost) at will.

What I did will work for YJs with 2 vacuum lines going to
the front axle. The simplest way to get a 2wd low would be
to put an on/off valve into the front vacuum line of the 4
on the t-case.  This line goes to the inboard port of the
shift motor and connects the front axle.  From 2wd close the
valve and shift into 4 L.  Front axle doesn't connect and
you have 2 L. However if you open the valve because 4 L is
needed you now have to shift back into 2 H, close the valve
and shift back.  To avoid having to do this I decided to
make things a bit more complicated.

I put a three way valve into the front vacuum line.  The in
line comes straight from the t-case switch.  One out line
runs through a drain cock(to let air out) and then to the
rest of the vacuum line.  I put a tee into the rear vacuum
line(connects to outboard shift motor port and disconnects
the axle) with the other output of the three way valve
tieing into the disconnect vacuum line.

Here's how it works.  In 'normal' position the three way
valve connects the two parts of the front vacuum
line(connect line).  With the drain cock closed everything
works as it normally would.  However if you move the valve
while in 2 H and close off the second part of the front
line(shift motor side), and then shift in to 4(H or L) the
front axle remains disconnected until you open the valve to
the shift motor side of the front vacuum line.  It now works
the same as described in the first paragraph.

What I did is allow me to switch between 2/4 L simply.
Leaving the 3-way valve in the 'normal' position I shift
into 4 L.  To go into 2 L I move open the valve to the
disconnect vacuum line(which it's tied into with the tee
fitting) and then open the drain cock to release the vacuum
inside the second part of the connect vacuum line(otherwise
the vacuum trapped inside won't let the motor disconnect).
To get back into 4wd I move the valve back to 'normal' and
close the drain cock(which can be closed right after the
vacuum is let out).

Works well enough for me.  The vacuum lines used are the
hard kind so I used 5/32" rubber line to slid over them.  I
also used brass fitings for copper tubing, brass 3 way valve
and drain cock as I couldn't find plastic in the size I
needed.  1/8" barbed tips were used to connect into the
5/32" rubber vacuum line.  I zipped tied every connection
and there are no leaks. Total cost was under $30 can be done
cheaper as the valve was $20.  I also made a couple of
unneeded connections due to supidity and could have saved a
little if those fittings weren't used.

Later,

Nick Falcetto                   '92 YJ Islander