Columbia B3 switch question

[mark180]

Should there always be vacuum in one of one of the lines coming out of the B3 valve?

[G.M.]

Originally Posted by wayoutwilli

Should there always be vacuum in one of one of the lines coming out of the B3 valve?

You didn't say what year Columbia? There are several types, the
early mechanical B3 and the later electrical valve. Vacuum is to
the electrical B3 through 2 electrical operated solenoids usually
mounted on the rear bottom corner of the drivers cyl head. These
solenoids are opened by the toggle switch and the clutch switch.
The is no vacuum supplied to B3 without one of the solenoid
valves providing it. You will only have vacuum to one of lines
going to the rear cyl to shift in or out of Columbia when vacuum
is going into B3. When vacuum is going to the side of the shift
cyl closest to the RR tire it is pulling the cyl OUT towards the tire.
When vacuum is applied to the OUT hose the IN hose closest to
the center of the rear through B3 is open to atmosphere. If the
opposite hose is not open the cyl don't have enough power to
shift. The shaft in the cyl extends through the end casting of the
cyl and operates a arm coming forward from the rear. When
the arm moves toward the tire the rear shifts OUT of Columbia,
arm moves toward center of rear and it is IN Columbia. It's
easy to remember, IN is IN and OUT is OUT. If you remove the
hose from the IN side of the cyl and it has black oil in it that
indicates the shaft seal at the IN side is leaking pulling oil and
air from the rear. This will make shifting sluggish or not go into
Columbia at all. Lubricate the large leather cups in the cyl with
Marvel Mystery Oil so it shifts smoothly. This can be done by
squirting a fair amount of MMO in the pipes on the cyl. G.M.

[mark180]

G.M.

Thanks for the reply. I'm running a '37 Columbia with all vacuum controls (no electrical). I was guessing that the button that gets pressed down when you push the clutch in is what makes the whole valve work. Without the clutch pressed in, there is no vacuum in either line coming out of of the B3

[Ken/Alabama]

It has vacuum on the which ever port is selected . When the button gets pushed down it opens a vent and allows incoming air for the piston in the shift can. If the piston in the can has vacuum on one side , it must be able to pull in air from the other side for it to move. If you suck on inlet port of the valve , you should get vacuum on one of the ports on the side.

[G.M.]

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Willi, vacuum don't come out it is a suction, If you don't have a vacuum
pump put a hose from the vacuum line of the engine to the single input
pipe on the valve. Test the valve and see if it shifts the vacuum on the 2
other pipes. G.M.