John,

That Lucas DC40 trouble light was used on pre war BSA's from the early thirties up to 1940 on all panel tank models. There are 2 type of fittings: one bajonet type and a type that has 2 holes in the side that fit over 2 small balls which are springloaded and situated in the panel."


BSA instrument panel complete with switches and wiring loom was apparently supplied to BSA as an assembly by Lucas. BSA panels have a part number stamped, presumably a Lucas number, many numbers have been obliterated by non standard chrome plating or other re-finishing.

66-8232 Instrument Panel complete. 1938 JM19 – JM23,(apparently includes wiring harness. Originally supplied by Lucas as an assembly, panels supplied painted to match tank, original photos often show slight colour variations, particularly matt silver)

66-8229 Instrument Panel Top, (bare metal panel only, with inspection lamp fitting for brass lamp, used 1937-1938. Panel stamped RD No 7710996 at front between ammeter and headlamp switch) (presumably Lucas number?)

24-5305 Instrument panel lamp with flex, brass type with holes at base for spring clips/balls, originally painted black (Lucas number? ) Several people around the world have replicated or partially replicated small quantities of the brass lamp.

The 24-5305 brass lamp only fits the 66-8229/RD No 7710996 panels which have corresponding spring clips/balls.

Regardless of the alleged official change to bakelite for 39, brass lamp and corresponding panel used by BSA on at least some 39 model bikes.

The bakelite lamp only fits the panels with bayonet/J slot fitting.
Judging by the parts books, Bakelite lamp appears to have been "officially" introduced for 39.

66-8253 Instrument Panel complete. 1939/40 (bayonet/J slot fitting, apparently includes wiring harness. Originally supplied by Lucas as an assembly)

Stamped number of 1939/40 bayonet/J slot panel unknown.

66-8254 Instrument panel lamp with flex, 1939/40 black bakelite type with bayonet/J slot fitting (Lucas 545096? DC40,??) available replica lamps can be re-worked to improve their authenticity. (some original bakelite lamps are marked Lucas DC40D)
Is DC40D correct for 1939/40 BSA? Or is DC40D a post war lamp?

Can anyone tell me the stamped number of 1939/40 bayonet/J slot panel?

Or fill in any of the other gaps?

"First, do no harm"

They were also used on pre-war Matchlesses including the Model X, G80,G90 and the AJS Model 2 and 2A. However AMC tended to use the bayonet fitting rather than the ball fitting. Cheers John