Substitute for Lucas PS9 31620 Tumbling dice switch for C15 Competition?

Started by createscript, 01 Jun, 2026, 08:48

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createscript

I'm converting a roadster C15 to off-road competition spec with lights.
I already have the Lucas PS6 rotary switch 31276 modern replica for the other side of the headlamp shell but the original Dip/Main switch used on these bikes was a Lucas PS9 31620 'Tumbling Dice' switch (see pics below). Originals are potentially available in various parts of the world but at huge cost (and maybe questionable reliability after 60 odd years!).
However, search as I might, these switches do not seem to be made in replica and I can't find anything with similar external appearance and function: I can find Lucas momentary off-on switches (like for screen wash etc.) that look the part but I need the latching on-on SPDT function of the original for the Dip/Main switch. I have also found all-metal and LED backlit switches that do the job, but would prefer something that looks the part i.e. black button and bezel. I'm not after rigid originality here, this is a replica build after all. 
Any ideas, anyone?

limeyrob

Those turn up at autojumbles. They are well made and last donkeys years and since they come apart they can be fixed.

createscript

Thanks, that's good news, wouldn't be the first time I'd dismantled and repaired switchgear. Any idea what the panel hole diameter is, so I can use a temp substitute until I find one?

Kev D

Hello. I've just whipped the bezel off the push switch on my Victor.
    Note that the bezel screws inside the switch housing rather than round the outside. There isn't much room for error if you drill a hole.
I would definately  wait until you have the chosen part before attacking the headlight bowl.
It's  quite a big hole to be left with if you can't  find an original.
Hope this helps.
Kev

createscript

Yeah Kev,
19mm, that's what I was thinking... :-\. On the other hand the few potential substitutes I've found have the On-On function but not the look I'm after and are all quite a bit smaller than that, so I can always open out if I'm lucky enough to encounter an original.
Not a whole load of autojumbles within easy reach of here (Shrops) in the next month as far as I can see, so it may be a good while before I can get looking.

Andy

createscript

For those with similar sourcing challenges, I found the following on eBay: AB6M-A2PBC Black 16mm Latching Round Push Button Switch IP65 DPDT (...and, for the record, I don't only search on eBay!).

Took a lot of changes in search terms, including accepting DPDT options which I should be able to adapt, but it only takes a 16mm panel hole and looks about as similar externally as I can reasonably hope for from a modern switch: I may even be able to substitute a different bezel.

I'm waiting for delivery but will update on the results when fitted.

Andy

createscript

Re: AB6M-A2PBC Black 16mm Latching Round Push Button Switch IP65 DPDT,
I have fitted the switch on the headlamp shell and wired it up. The switch comes with 8 contacts all very close together, so after establishing which contacts were needed for simple On-On operation, I clipped off the ones not needed and soldered on spade connectors to the remaining 3. The panel hole is 16mm so if I do locate a suitable original Tumbling dice switch, I can open out the hole a bit more.

I am very happy with the device as a reasonable look-alike substitute, and, of course I could do with a chrome bezel but needs must. Hope this helps anyone after similar.
Andy

Kev D

Quote from: createscript on 11 Jun, 2026, 08:18 Re: AB6M-A2PBC Black 16mm Latching Round Push Button Switch IP65 DPDT,
I have fitted the switch on the headlamp shell and wired it up. The switch comes with 8 contacts all very close together, so after establishing which contacts were needed for simple On-On operation, I clipped off the ones not needed and soldered on spade connectors to the remaining 3. The panel hole is 16mm so if I do locate a suitable original Tumbling dice switch, I can open out the hole a bit more.

I am very happy with the device as a reasonable look-alike substitute, and, of course I could do with a chrome bezel but needs must. Hope this helps anyone after similar.
Andy

Glad that you found something .And lt could indeed prove useful to other people👍