Missing screw for Lucas PRS8 switch solution.

[Plugsnpoints]

Recently I purchased a new wiring loom for my coil ignition M16 from Colin Farrington. This is great quality and easily installed. I decided to replace the ageing PRS8 lighting/ignition switch.


It all worked so well until the (I'm guessing not too unusual problem!) grub screw holding the lighting knob dropped out, never to be seen again.


I discovered you can buy a replacement key and knob, but not the grub screw for the newer (foreign) Lucas switch. The original is a BA thread. The new one is metric (don't tell the rivet counters!).


Due to me not wanting to spent another 70 odd quid on a switch I looked though my odds and sods boxes. Having spent twenty years out on site as a sparky I found the perfect solution.


The thread is 3.5mm (the same as socket/switch retaining screws). A normal three and a half mill screw isn't fat enough, but a 'pedestal' screw extender is. These are for when the back box is buried far too deep in the plaster and normal screws aren't long enough.


All I did was to cut the thread down, and chop a bit of the hexagon with a Dremel, then with a fine cutting disc put a slot in the end. I had to gently file the hexagon round to make sure it fitted neatly in the knob. It took me half an hour tops.



That's my top tip today for anyone with a loose knob! Seriously though, the PRS8 was fitted to many machines, including Tiger Cubs. It might get you out of a fix.


The pedestal screws can be bought from any electrical wholesalers for a few pennies.

[Expat]

Nice!