W/NG - Lucas DU42

 Originality creeps closer with every passing blog post at the moment, this time with a genuine Lucas DU42 headlamp. The bike has worn a Indian replica since I've had it, and since one came up within the club a while back I've had a plan to replace it, with a bit of help from Wali Taylor who came up with the proper flat glass.

This picture comes from the W/NG workshop manual and shows the BA15 bulb holder, with adjustable focus (C), held in place with the long spring clip and the early rim clip (A) my bike would have worn:

The long spring clips (B) are retained to the reflector with two little sheet metal clips, riveted to the reflector. One of mine was rusted away, so here is the replacement made from a scrap of 0.5 mm sheet steel:

Here's the beginning of a rivet made from 2.5 mm² annealed copper wire:

The next thing we need is the gasket and the glass, shown in this later diagram from a 1944 parts book where the ammeter has been deleted and the headlamp switch moved to under the seat, with the new hi/lo pushbutton in the headlamp panel:

I've decided to use round section foam strip for the gasket; the glass is original, from Wali Taylor of the AOMCC.

The clip came from eBay, but didn't fit until I gave it some attention. The rim was full of dents too, but with a panel beating hammer and a dolly I soon had that smoothed out.

The clip is retained with a bit of piano wire - this is about 2 mm in diameter:

Onto the bulb holder. This is a military pattern bulb holder - there is only one contact for the main bulb, and I guess I will make another. Also very visible here is the clamping screw that allows the bulb holder to move backwards and forwards to position the filament at the primary focal point of the reflector.

Here's the view from the other side. Needs a clean but it is in good shape - it's not distorted at all.

Next is the instrument & switch panel. This is the illustration in the manual:

This is the one that came with the shell: it's a bit early for the W/NG as it has the fitting for the half charge resistor - that little casting between the ammeter and the switch hole:

This switch panel would be 1932-36, as the earlier H52 headlamp is quite different and the half-charge resistor disappeared with the introduction of the MCR1 mechanical charge regulator in 1937. I might use this or perhaps the repro one that is fitted to the bike at the moment.

This is the only original Lucas shell I have with the holes for the rubber string seal. Here it is in place - it’s a 2 mm sponge EPDM round section:

There will be a bit of wiring to do as the repro ammeter currently on the bike has terminal posts and ring terminals, and the headlamp is wired up with Japanese bullets:

I've chosen a CDRC Double Dipper Pro projector headlamp bulb:

This is the beam it produces, in a picture taken on my phone using the 'night' setting.

With the camera set for daytime you can see the bulb is using the high beam LED and the low beam LED:

The completed headlamp:

Installed: