BSA WD M20 Electrical Equipment

Created with the kind help of Steve Madden, Co-Author, British Forces Motorcycles 1925 - 1945.  
Click on the pictures to enlarge!
Electrical Horns
The civilian 1940 BSA parts list states that a Lucas Electric Horn type 700771 was fitted to the M20. According to the Lucas parts book this is a Lucas HF1140.

The 1940 Military BSA parts list states a Lucas Electric Horn type 701717 for the M20, no further information about this model horn yet. More information about WD Electric Horns is very welcome.

Horn new 001.jpg (83675 bytes)
Here a factory picture of a 1939 KM20 with MT1130 1940 model taillight fitted which should be fitted with a HF1140 according to the parts book.
Horn HF1140a.jpg (34747 bytes) Horn HF1140b.jpg (70261 bytes)
Lucas HF1140 as used on the 1940 model M20.
Horn new 002.jpg (54496 bytes)
This is a factory picture that shows a bike with frame number WM20 30775 what makes it a 1941 motorcycle.
Horn new 003.jpg (58992 bytes)
This is a factory picture that shows a bike with frame number WM20 52778 what makes it a 1942 motorcycle.
HF1140 1.jpg (49116 bytes) HF1140 2.jpg (42318 bytes) HF1140 4.jpg (86275 bytes) HF1140 3.jpg (82232 bytes)
Lucas Electric Horn type HF1141 dated 8-42.
Horn used 005.jpg (95687 bytes)
This is a picture that shows a bike with frame number WM20 79556 what makes it a 1942 motorcycle fitted with a HF1235 horn. It seems that during 1942 they changed from the Lucas HF1141 to the Lucas HF1235 horn.
HF1235 1.jpg (99783 bytes) HF1235 2.jpg (99553 bytes) HF1235 3.jpg (84073 bytes)
Lucas Electric Horn type HF1235 dated 9-43.
Horn restored 001.jpg (31672 bytes)  Horn restored 003.jpg (49723 bytes) Horn_restored_002.jpg (36063 bytes) Horn_restored_004.jpg (40858 bytes)
These pictures shows a HF1235 horn, this horn is dated 1-44. There are two Lucas HF1235 WD Body casting patterns, one with a flush adjuster screw head one with a recess adjuster screw head. The one with the flush adjuster head has been continued as civilian post ww2 pattern while the one with the recess pattern became introduced again for the 1951/2 HF1235 pattern.
 Horn restored 001.JPG (88448 bytes) Horn restored 003.jpg (86294 bytes) Horn restored 002.JPG (80959 bytes)
These pictures shows a HF1235 horn being rebuild by Boudewijn. This horn is dated 10-44.
Horn new 004.jpg (88342 bytes)
This is a factory picture that shows a bike with frame number WM20 116xxx what makes it a 1945 motorcycle which seems to be fitted with a Lucas HF1235 horn.
Horn used 001.jpg (126234 bytes) Horn used 002.jpg (110851 bytes) Horn used 003.jpg (71205 bytes) Horn used 004.jpg (52616 bytes)  
These four pictures appear to have the same horn which are probably Clearhooters.
HF180 clearhootera.JPG (52971 bytes) HF180 clearhooterb.JPG (56023 bytes)
Clearhooter HF180 (removed from a 1941 Enfield WD/C)
headlight8.jpg (86144 bytes)
LUCAS 8" Size Panel Headlight TYPE DU 142, used on BSA WD M20 up to late-1941/early 42.
headlight6.jpg (83521 bytes)
LUCAS 6" Size Panel Headlight TYPE DU 42, used on BSA WD M20 from early-1942.
ammeter01.jpg (93720 bytes) ammeter02.jpg (90425 bytes)
Lucas CZ27 ammeter.
The standard ammeter fitted throughout the war years to all machines was a Lucas TYPE CZ 27. Late-war produced machines (late-44/early 45) dispensed with the ammeter and had a different light-switch fitted.  The CZ 27 ammeter was not specific to WD-use and was introduced during the 1930's for civilian machines and continued in service after the war through to the 1950's. These ammeters are very robust, however, they are also extremely difficult to find today.
Light switch
switch01.jpg (89964 bytes) switch02.jpg (110268 bytes)
War time switches.
The standard light switch fitted throughout the war years was a Lucas 4-position switch, the additional position being a "T" for "tail-light". This position was used for convoy duties and would illuminate the rear-lamp only. Late-war produced machines employed a different 4-position switch in conjunction with the removal of the ammeter. This later pattern of switch did not last long and the common earlier type of 4-position WD switch continued in use on WD -machines through to the 1960's.
Late-war switches were Little seen and used, this switch looks identical to the common switch but has different positions, these being "Test, Off, L, H" (for "test, off, low beam and high beam"). This switch was mounted in a steel rectangular plate with a pointed lower-end, usually on a strip-bracket affixed below the bike's saddle and extending off the right-side saddle spring mounting bracket. The open rear of the switch was then covered by a large domed black bakelite detachable cover. The ammeter was no longer fitted to the machine, the panel on the headlight having a blank, uncut area where the ammeter would have normally been. In place of the light switch was fitted a large black bakelite "push" button, marked on top "P" (for "push"). On pushing this button the rider changed from main beam to low beam, and vice-versa). With the ammeter missing, the idea of this system to see if the dynamo was charging was to turn the switch to the "test" position and to rev-up the bike's engine. If, on doing this, the tail-light bulb was seen to glow brightly, then the system was seen to be charging.
lateswitch01.jpg (89639 bytes) lateswitch02.jpg (56730 bytes)
Late-war switch and push button.
Black-out masks
The common WD-type of blackout mask was not introduced until late-1941, both 8" and 6" sizes. Prior to this, all WD bikes were fitted with a thin-card shield within the headlight. This was officially termed "Mask, Black Manilla" (manilla being the type of thin card used). This early mask was simply a simple circle of thin black card cut to the appropriate size with the centre bearing a half-circle cut-out (to show on the lower portion) to emit light from. It was fitted BEHIND the headlight glass, in front of the reflector. To assist the restricted lighting, the lower-half of the headlight reflector was supposed to be painted black too, to divert reflections downwards.
black-out03.jpg (100990 bytes)
Painted lower-half of the reflector.
There are several patterns of hooded blackout shield, not all made by Lucas....many other firms produced them too. They do not all have a second (lower) apperture for the low-beam or pilot-light, and if they do, the hole can be very, very small on certain early examples......the hooded masks were generally finished in flat black paint by the manufacturer, ranging from a dead matt shade through to a semi-gloss black.....some bear the manufacturers markings.....ALL types of blackout mask were fitted by the manufacturer at the factory. Indeed, in most cases, they are listed within the bike's parts list.
black-out01.jpg (110958 bytes) black-out02.jpg (82991 bytes)  
8"and 6"blackout masks.
Lucas L WD MCT1 WD-pattern tail-light
On the early military models certain "pre-war" features were fitted such as the Lucas MT110 tail-light and the scarce 1940 Lucas  MT1130 streamlined "art-deco" style tail-light.
MT110.jpg (58977 bytes)
Lucas MT110 taillight.
lucas MT110.jpg (88346 bytes)
Lucas MT110 taillight.
torpedo.jpg (72960 bytes)
Lucas MT1130 taillight
lucas 211.jpg (86531 bytes)
Lucas MT1130 taillight.
Civilian model taillights as used before the standard WD-pattern tail-light was introduced.
There are two main versions of the Lucas WD-pattern tail-light. The first pattern, introduced in late-1940/early-1941, is distinctive in that it has a black rubber seal permanently fixed beneath the bulb-holder and lens-cover mounting using the securing rivets. The cover then extends outwards to cover the join between the lens cover and the cover mounting, providing a waterproof seal. This type of tail lamp was discontinued by 1943 and a modified pattern introduced which was identical but lacking the rubber seal. This was due to rubber shortages. This later lamp is the one commonly encountered today. 
taillight02.jpg (81321 bytes)
Fag-end taillight, missing it's waterproof seal.
There were 3 distinctive types of lens cover for the two types of lamp. The initial model with the tiny rear-lens. This was soon nicknamed the "fag-end" tail light as the light emitted was considered the same as the end of a burning cigarette ! This light was a reminder of the severe blackout regulations in force at the time of it's introduction. These lenses were used in conjunction with the first-pattern lamp. In 1942/43 a second pattern lens cover was introduced, identical to the previous model but with a larger red-lens that did not provide excessive glare. This lens was fitted to both the first and second pattern lamps. In 1944/45 a third pattern lens cover was introduced, identical to the second pattern but with a rectangular covered aperture cut into the lower-part of the cover-body to provide illumination to the rear mudguard and numberplate (if fitted). This later cover was introduced due to a relaxation in blackout regulations and to assist with convoy marshalling and recognition. Some of these later covers are marked on the top "MT3" (the class of stores from which the lens cover is catalogued).
taillight01.jpg (65444 bytes) taillight05.JPG (98480 bytes) taillight06.JPG (106440 bytes) taillight07.JPG (78369 bytes) taillight08.JPG (78253 bytes)
First pattern taillight with waterproof seal with second pattern lens.
The first model lamp is marked on the reverse of the body with "Joseph Lucas Ltd, Birmingham". The second model is usually lacking this, but has stamped onto the lower-front of the body "L WD MCT1". Those lamps produced from 1944/45 onwards are normally marked "L WD MCT1A", the "A" referring to "aperture" in conjunction with the third pattern lens cover by then usually supplied with the lamp.
taillight03.jpg (72255 bytes)
Second pattern taillight dated October 1943.
The 2nd pattern lamp, marked "A", is commonly found today together with the third pattern cover. Many are brand-new and still in boxes, having sat unused in stores. The WD-tail light did not last in service longer than a couple of years after the war, as rear number plates and improved civilian-pattern lighting reappeared on military bikes. The first-pattern rear light is very hard to find today, as most were used up. The second pattern lens cover still turns up at autojumbles but the first pattern cover is very difficult to locate.
taillight04.jpg (70698 bytes)
 Second pattern taillight new in it's box.
Dynamo re-polarization
Lucas Dynamo.jpg (105617 bytes)