P11 Kill Button

Ron L

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Since the forum has been a little slow lately, I'm going to try to describe what I have learned and have yet to learn about the Lucas 35601 stop switch. Over the years I have collected a handful of new and used 35601A switches and read everything I could about them. Most of the information is from Triumph and BSA sources as I found little information from Norton or Lucas. Unfortunately, much of what I found has been proven incorrect by my testing of the switches I have in my collection.

1) "There are two different 35601A switches differentiated by a black or brown button. " This appears to be substantiated by a Triumph service bulletin from January 1966. It states that the brown button models are suitable for battery and coil ignition motorcycles while the black button models are only suitable for AC energy transfer ignition. What could be the difference? Well looking at the ET wiring diagrams vs. the battery and coil (P11), we see the kill button on the ET ignition simply connects the points leads together.

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The kill button on the battery and coil ignition (on a P11) takes both the points to ground at the handlebar.

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So the switch for battery and coil version will show continuity from each connection to the metal switch body when the button is depressed. The version for the ET ignition only shows continuity between the two terminals when the button is depressed and not between either terminal and the metal body.

Sounds good. Brown button for battery and coil and black button for ET. Maybe this was true back in 1966, but the half dozen or so buttons I have are a mixture of black and brown and all will ground through the housing. Hmmm... Maybe manufacturing was changed after 1966. Certainly the ground through the housing button will work for ET ignitions as well, so why make two versions.

2) The 31071 button does not ground to the housing when depressed. That is my experience when I test the one example I have. Perhaps Lucas changed the number on the ET variant to 31071 at some point and discontinued using brown buttons on the battery and coil 35601?

3) If you are using an electronic ignition on your P11, to use either of these buttons you should install a relay. You want to open the circuit to the electronic box, not send it to ground. Set up the relay so it is normally closed on the ignition side and grounding the button will energize the relay coil.

4) The difference in the housing for this switch between Triumph and P11 has been documented before, but to reiterate, the Triumph is stamped steel while the P11 is machined and is thicker and has a square shoulder compared to the Triumph.

I hope this helps somebody, and if you have any different results, let us know.
 
It doesn’t look these kill switches are being repopped, just the black button, non grounded version. I need a couple for my bikes, anybody have some spares they’d like to sell?
 
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It doesn’t look these kill switches are being repopped, just the black button, non grounded version. I need a couple for my bikes, anybody have some spares they’d like to sell?
But are you sure they are not grounded? As I said, I have 3 or 4 black button 35601's that are grounded. To make things more confusing, those brown buttons are probably getting darker with age and harder to distinguish from the black ones.
 
Definitely not grounded, just a N/O contact between the two contacts.
 
Definitely not grounded, just a N/O contact between the two contacts.
I understand what you are saying. However, testing the handful of buttons I have with a Fluke VOM, they definitely have contact between the terminal and body when the button is depressed. I was as surprised as you. I suggest you test any 35601 before you use it. As the Triumph bulletin says, the grounded button may be used for either ET ignition or battery and coil, but you can't use the ungrounded button for battery and coil igniton. I believe Lucas changed their practice sometime after 1966 to make black button 35601's with the body ground loop. Just a theory.
 
My testing shows this bulletin is not always correct!

P11 Kill Button
 
Hello Ron L.

I've had a request from Anthony Curzon to ask your permission to use this kill switch article for his P11 book
OK with you? It's good information.
 
4) The difference in the housing for this switch between Triumph and P11 has been documented before, but to reiterate, the Triumph is stamped steel while the P11 is machined and is thicker and has a square shoulder compared to the Triumph.

Ron L can you share a picture of the machined housing?
Note: I have 4 housings with black and brown button switch on the shelf. They all look like stamped steel.

Thanks
 
Ron L can you share a picture of the machined housing?
Note: I have 4 housings with black and brown button switch on the shelf. They all look like stamped steel.

Thanks

 
I’ve still been hunting for the correct grounding PB, thought I hit pay dirt at the Bonneville Shop. BS shows a PB, Lucas number SPB105, and state in a big note that it is a grounding type button and is not to be used on electronic ignition bikes. Don’t be fooled, it is the non-grounding type, and they won’t accept returns on electrical components, so I’m stuck with it. I then contacted John at Motoparts in Edmonton and as usual he had a decent used one on the shelf. Motoparts to the rescue again!
 
If you use a 5 pin relay and connect the EI to pin 87A (normally closed) and pin 30 to switched 12 volt power and pin 85 to switched 12 volt power and pin 86 to one of the two wires on the kill button, the EI will be powered until the button is pressed and the coil disconnects pin 87A and cuts the power.
 
Hello Ron L.

I've had a request from Anthony Curzon to ask your permission to use this kill switch article for his P11 book
OK with you? It's good information.
Hello Ron L.

I've had a request from Anthony Curzon to ask your permission to use this kill switch article for his P11 book
OK with you? It's good information.
Moses 'spent' less time writing the 12 plates and did not even win the Pulitzer Prize
 
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