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Anyone know why there’s a reversed style pre 1970 Lucas brake light switch ?? Unless installed upside down, applying brake would release loaded tension to complete circuit. Never seen this before. Can’t make sense of it. Thanks. First pic is reversed one
 

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Discussion Starter #4
Thanks for the reply, ones push & ones pull . Look at pic closely. One has pull end on the right & the other on left. The one that’s facing the rear of the bike would have to be held out & when applying brake would release inward. Just the opposite on the typical switch. Make sense ? Thanks
 

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Hi catchalot, Hmm, see what you mean. I was wrong on orientation, fat part is at bottom also on 31383. 31383 is indeed push the activator end for off. Looking at a few books I see 31383 is used for not only pre unit, but later 500s also such as a '66. Parts book shows a flat "hoop" with a cotter pin(split pin) through it. This hoop is clamped to brake rod. Looks like hoop surrounds the fat end of switch activator(the end without rivet & hole & the cotter pin goes through center of hoop. So when brake is released the hoop/cotter pin pushes activator to rear which opens contacts. Very clever those Brits!

So not only is the activator bar reversed, the internals are different also. Would be fun to take both apart & see how they do this. I see some call your switch a "spring pull" switch (99-0725). Now, that makes sense compared to the 31383.

Once I figured it out, very easy to tell what switch is what.

Here's a link to 1966 500 parts book. See pg 46 for the illustration.


Interesting some parts sellers seem to think these switches interchange..... As you pointed out, they do not.

Here's the 99-0725 spring pull on the '69 Bonnie.
Don
 

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mount the backwards pull one upside down then it will work :whistle:

You guys are forgetting LUCA$ made many, many switches for many vehicles. There are any number that may look the same or similar but do not function the same.

K
 
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