Amelia Squariel: Charlie’s Shed – Lucas U39 swap repairs

I’ve received a number of Lucas U39 switches – in truth they’re on many of the bikes. I’ve two on the bench for the time being, a civilian one from the FH and a army one destined for the W/NG, which has an additional place which illuminates the tail mild solely.

These notes are meant to document a number of areas the place these switches get broken and to point out methods they are often repaired. You’ll want a number of easy instruments and supplies.

The primary drawback is the rotor – the half that matches within the knob is worn. It’s presupposed to be a cylinder with two flats, however the flats are so worn & corroded that the knob wobbles about. What I’ve finished right here is make a fence across the shaft with sellotape and stuffed within the centre with JB Weld. It had beforehand been totally cleaned with alcohol.

Here’s a shut up view of the completed rotor – I’ve used needle information to revive the form of the flats becoming into the knob, being cautious to make sure the pointer aligns with the textual content moulded into the highest of the swap:

Subsequent is a Bakelite restore, once more with JB Weld. Somebody has tried to prise the swap out of a panel with a screwdriver and damaged the moulding in a number of locations:

To repair these issues, the very first thing to do is clear all of it down with degreasers, brushes and scraping. I constructed a fence across the restore with some plastic card:

Eradicating the fence reveals hardened resin prepared for shaping:

A brief session with a flat file produces one thing we are able to paint:

Subsequent up, the contacts. A few of these switches have shifting contacts operated by the rotor, which get corroded and stuffed with muck. On this case, the spring had corroded away; to take away these contacts you must withdraw a tiny cut up pin. I needed to drill what remained of the cut up pin out with a 1 mm drill in a pin chuck. 

You should buy these torsion springs on eBay, however upon getting made a number of and maybe have a number of bits of piano wire mendacity round in numerous diameters it’s simpler to make your personal.