Adjust venturi switch?

[teahead]

Reading through:

https://www.sl113.org/forums/index.php?topic=24794.0

How does one adjust that switch?  I took mine apart and cleaned up the inside.

Didn't think it was adjustable.

Also, how does one test it?

[Pawel66]

Some clues here:

https://www.sl113.org/forums/index.php?topic=13583.msg92311#msg92311

I have it set to open right after I press the pedal when CSS is activated + slack.

You losen the two allen screws that hold the switch. It can then rotate around the throttle axis (one of the holes in the switch casing is oblong). You set the switch and tighten the screws.

[teahead]

Some clues here:

https://www.sl113.org/forums/index.php?topic=13583.msg92311#msg92311

I have it set to open right after I press the pedal when CSS is activated + slack.

You losen the two allen screws that hold the switch. It can then rotate around the throttle axis (one of the holes in the switch casing is oblong). You set the switch and tighten the screws.

I'm confused (as always) on those instructions.

Disconnect the two wires?  Why would you do that?  How do you adjust the Venturi Switch if you disconnect the wires?

Seems that you would put your test light on while they're attached so that you can rotate it while the car is running.

The two wires go to the 3-position solenoid, right?

[wwheeler]

You have to remove the wires when using an Ohm meter because you will get feedback from the wiring when connected. What you are wanting to see with the Ohm meter, is what position is the switch (contact points) open and closed. That is how you adjust this. The switch should be open just after the throttle is applied with the CSS activated as Pawell said.

[Pawel66]

As Wallace says, it goes like: power from fuse 3, through the switch to the 3 position solenoid.

Solenoid has minimum resistance. It is difficult sometimes to see with meter if the switch is open or close,  as when closed, you get the solenoid resistance in reading when closed, which is close to zero. And when open it is also zero.

Hook up bulb i n series - then you see it. All you need to know is when the switch opens - bulb in series will not be lit.

[teahead]

Seems like you can just put a test light on one of the terminals while the wires are hooked up.

When revving the motor, the test light should turn off by 1600 RPM.

[Pawel66]

Well, in essence you are testing when a switch is open. Power is applied to one contact and appears on the other when it is closed, goes away when it is open.

Because solenoid has small resistance, the best is to disconnect wires, hook bulb to + and to one of the contacts and the other contact to ground.

Bulb lit - switch closed, bulb off, switch opened.

i think it may be a good practice to set switch to open right after CSS pushes rods on gear selection + slack in linkage. 1600 is said to be max in BBB, I would find it personally too much. The opening of the switch  puts gearbox in "shift up ready" mode and you may want it to happen when you start pressing gas pedal while in gear, which means right after CSS pushed linkage + slack in linkage.

[wwheeler]

As Pawell says, I think 1600 rpm is too high. What you don't want is the switch constantly switching on and off at part throttle. That will burn that and the solenoid out at a quicker rate. It is best in my opinion to adjust as stated earlier. The purpose of this switch is to lower the PSI in the trans so it will downshift smoothly. There is no point to having it set too high.

On the other hand, you do not want it it so close with the throttle closed that the switch can cycle on and off. That is where the slack comes in that Pawell mentions. It just provides a cushion for unknown variables.

This is a bit off topic, but I added a 4 post relay so this poor little (and expensive) switch doesn't bear the full burden of the solenoid's amperage. I have had issues with over the years and now with the relay, it works to perfection.

[teahead]

Anyone know which way to rotate it for later switching?  Or sooner switching?

[Pawel66]

If you turn it same direction as throttle, it should open later right?

You may want to experiment a bit...

[teahead]

OK, light turns off at about 1200 rpm, thanks to my wife helping out.

Car still shifts hard and late.

*sigh*

Don't think it's the linkage since downshift seems OK (no clunking) but I guess that should be my next endeavor before checking out the pressure port.

[wwheeler]

I would think that when trans is in the low pressure mode, the only thing it would control are the downshifts when you foot is off the pedal (de-accelearting). So if that part is good, your late, hard shifts issue is somewhere else.