How to Rebuild a Lucas ignition Switch to Better than New

Post date: Dec 25, 2011 12:33:37 PM

It's possible to rebuild a Lucas ignition switch to better-than-new, although it's tedious. The trick is to give the contacts a greater resemblance to a Japanese ignition switch. If you take apart an old Honda switch, for example, you'll see that a wiper contact moves back and forth over several brass contacts mounted in a sheet of fibreglass /resin material (whatever it's called -- I'm calling it "fibreboard" here). The contacts are mounted so they're dead flat with the surface of the fibreboard, which is very smooth, so the wiper contact can move from contact to contact with no jolts and very little friction.

Contrast this to the Lucas design: take the back off the Lucas switch and you see a similar array of contacts except that they're crudely formed and pressed into the fibreboard, sticking up like nail heads that weren't hammered in all the way. Then a second piece of fibreboard with holes in it is laid [not glued] on top of the first one, so when you turn the key, the wiper contact falls down into each hole, gets dragged up across the [not so smooth] surface of the contact, then down the other side and up out of the hole toward the next one, resulting in a lot of slop, which gets progressively worse since the fibreboard with the holes can move around against the one with the contacts until they're not even concentric to the holes anymore. In short, the Honda switch was built to last and the Lucas one to sell . . . cheap.

But you can make the Lucas contact-plate like the Honda one: clean both pieces of fibreboard thoroughly and epoxy them together, making sure to fill the holes completely with epoxy. Then sand the surface down on a piece of sandpaper on glass until the contacts are dead flat against the surface of the fibreboard and there are no voids anywhere, finishing with fine sandpaper so the contacts are shiny. Now the wiper can slide easily over the contacts, prolonging their smooth surface and its own life.

Finally, there is a sort of dam halfway between the keyhole and the contacts to keep the water from getting in. Being Lucas, it's made of cardboard, or at least it was on mine, so coat it with silicone or epoxy to give it at least a chance to stay in one piece.


When the back is off the switch, you can still put the key in and switch it to the four click-stopped positions (parking light, off, engine only, and engine with lights). This is fine, but you can also click it BEYOND the four click stopped positions. If you do that in either direction, a little ball bearing on a spring will pop out of its hole and you'll have more hell than you want finding it and getting it back in. It's nice to clean and re-grease this area while it's accessible, but pay attention and DO NOT turn it beyond the click stopped positions