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How does the sportomatic microswitch in the shifter work
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eviloval
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Joined: May 03, 2003
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PostPosted: Sun Nov 05, 2017 4:49 pm    Post subject: How does the sportomatic microswitch in the shifter work Reply with quote

Ok...this may be a pair of lame questions and any and all help will be appreciated. I have a 70 beetle autostick and while I'm not a fan of it being all stock I'd like to modify it to suit my tastes (short of converting it to a 4 speed). One of those modifications would be to use an aftermarket shifter in place of the stock one and keep the ability to change gears by just moving the lever.

I've researched a bit but have not found how the microswitch in the sportomatic changes gears....or how the microswitch gets activated with a gear change. It appears to go on the movable portion of the stick so if its not locked into place how does the microswitch activate?

Also, I understand that all of this is very far fetched since there's a real difference in the level of technology between a porsche and a beetle of the same era. But, the control servo on a carb'd base sportomatic only has 3 vacuum lines. Looking at the diagrams I see that the control valve vacuum line attached to the intake manifold runs thru a set of check valves just below the carb throttle plate. How do these check valves work....are they holding different vacuum pressures or are they the same.

Any and all help as mentioned is greatly appreciated.


Last edited by eviloval on Mon Nov 06, 2017 10:08 am; edited 1 time in total
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914sgofast2
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Joined: May 29, 2017
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Location: California
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PostPosted: Sun Nov 05, 2017 11:11 pm    Post subject: Re: How does the sportomatic microswitch in the shifter work Reply with quote

When you touch/move the gear selector, the microswitch "closes" and sends an electric signal to the electric solenoid that activates the vacuum servo on the clutch/torque converter unit. The switch in essence "disengages" the clutch/torque converter unit so you can shift between gears. When you let go of the gear shift lever, the microswitch "opens" and the clutch then re-engages in the torque converter unit and transmitts power to the rear wheels.

Mercedes Benz used a somewhat similar system on its cars in the late 1950's before it began installing fully automatic transmissions in 1961. I had one of those automatic clutches on a 1958 Mercedes 220S. It's a decent enough system for people who don't yet know how to drive a clutch, but the shifts are very slow compared to a standard clutch and manual transmission. In the Mercedes system, you still had to let your foot off the gas when shifting between gears to avoid over-reving the engine.
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