(NOTE: What follows reflects the author's 45 years of ownership/research into these vehicles. While research by several people is continuing, it reflects the best he can offer based on conclusions/confirmation of original features at the current time. It concentrates on cosmetics rather than mechanical etc detail and seeks to identify some of the more common errors made in restoring these vehicles. Although indicative dates are indicated, there was some overlap. Although some things are listed as errors, given current day scarcity of some items it is recognised that some restorers may have no option.)
Basically, three designs. Early cars, to around just after car 071 or so on had a radiator with a smaller mesh grille than later, the radiator having a more pronounced taper towards the front. Both these, and the later cars with a larger mesh grille had a half moon cut out centrally at the bottom to allow insertion of a crank handle. This was matched by a half moon cut-out top centre of the number plate valance. Error: Not including the cut-out in a new or rebuilt radiator. The mesh grilles were chromed (the author has never seen an original mesh grille which wasn't) and generally carried a flat etched badge on the grille and a "Flying M" mascot on the radiator cap (the author is aware of one very late car which didn't have the mascot, there may have been a few more). There were brackets to each side of the bottom tank which fixed the radiator in place by being bolted to the side of the front cross tube assembly.
From some time in 1938 the bar grille became available topping a new radiator design. The number plate valance was hinged so that it could be raised to allow for a crank handle. The radiator was located via a brass plate attached to the bottom of the bottom tank bolted to two brackets extending from the front of the chassis. This plate tapered out at either end from the rear edges at the bottom of the chromed radiator cowl sides to match up with the number plate valance which was wider than the radiator. There was a slight kick-up at each end which then folded down and doubled on itself for strength.
The bar grilles were painted, not chromed, and generally carried a cast, raised badge. The author has never seen an original radiator grille which was chromed (there may have been a very small number eg on display vehicles but he has never been able to actually confirm this), and the contemporary photos support this. These radiators had a plain radiator cap; they did not have the "Flying M" mascot (the author in 45 years has only been able to identify two cars so fitted, both Factory "specials"). Errors: Adding a "Flying M" mascot to these radiators; chroming the grille; not having the hinged number plate valance.
The cars used the Burman-Douglas worm and nut system. Some early cars were claimed to have been fitted with a reduction gear, similar to three-wheelers, mounted halfway down the column, but the author is sceptical as to whether any production cars were actually fitted with this system. About the 1950's/1960's the Factory offered a conversion kit to retrofit the CamGears Ltd steering box, a Bishop Cam design, to Series 1 cars and a number have been so fitted. The immediate differentiation points are that the Burman-Douglas end plate is triangular with three quarter inch BSF attachment bolts, while the Gam Gears box has a square plate with four attachment bolts. The latter box also has a plug about a foot up the outer column from its junction with the box, and the steering wheel is on a spline rather than on a taper with a Woodruff key.
Steering wheels. 1930's vehicles predominantly used an Ashby 16" diameter Brooklands steering wheel. This was a sprung wheel with four spokes each comprising five stainless steel rods. At the hub end these were clamped in a two piece boss held together with four quarter inch BFS nuts and bolts. There was a round spacer a little up the spoke. At the rim end, the spokes were encased in a plastic substance with a small flare at its inner end. Some time in the late 1930's a switch was made to a much cheaper steering wheel with three sprung spokes fixed in a one-piece alloy boss. However, a few post-war cars were still fitted with the Ashby wheel. NOTE: The Bluemel's "Brooklands" wheel, which was a copy of the Ashby wheel, albeit with slight differences, and made to Ashby's patent, is regarded as an acceptable substitute for both wheels, given their scarcity.
Pre-war cars generally had white on black instruments, the clusters having curved glasses. The cream/very dark brown faced instruments, were the normal post-war fitment and also fitted to some late pre-war cars. Illumination on the earlier cars was by two divers' helmet lights mounted on the outside of then instrument panel, while the later instruments were illuminated from under the dash via cut-outs in the sides of the instrument bodies (clusters) and two internal lights (speedometers).
The clusters are very similar to those in some Riley, pre-war MG and some other vehicles, while the speedometer/clock is the same as on some pre-war Austins albeit with different speed indications. Errors/to watch out for. Some exchange cluster assemblies have been found to have instruments grafted in from other vehicles in which the cut-outs are covered over by metal plates. Have these removed if yours are like this and use perspex windows to protect the insides. Do not be tempted to fit divers' helmet lights to cars with these instruments.
Basically three types, aside from the Drop head coupes which had slight differences (eg location of the horn button) Re pre-war cars, the Coventry Climax engined cars had the speedometer above the horn and the switches/knobs (aside from the ignition/lighting switch) were in a row along the bottom of the instrument panel, the starter and choke knobs on the left and the throttle on the right. Reading left to right, the knobs were mixture (ie choke), starter, panel light, then the throttle.The pre-war Standard Special cars had essentially the same panel, but with the starter and choke knobs on the right (ie driver's side R/H drive) the choke being up above the starter. The panel light switch moved to just above the ignition/lighting switch. There was no hand throttle fitted.
The post-war instrument panels, with the brown/cream instruments, reversed the positioning of the speedometer and horn button, the horn button going to the top. On cars with dipping headlights the switch for the centre spotlight is normally between the starter and choke cable knobs.
Headlights on the earlier pre-war cars were the LBD 148 moving to the MBD140 design just before World War 2. Export cars at least after the War had dipping headlights either by means of a twin filament bulb or a solenoid operated dipping reflector. Sidelights were the Lucas 1130 variety, the centre-mounted taillight /stoplight was the Lucas ST 38 pre-war, and the Lucas ST 52 post war. The latter are now very scarce. A very few cars were fitted with the Lucas ST 51 ("D" lamp), usually in pairs equidistant from the car's centre either side of the number plate. Errors Using the later S700 headlamps as fitted to the Plus 4.
The prefixes on the lights :
. L is used on models normally fitted with separate reflector and lens to denote light unit;
. M, standard lamp with separate reflector and lens, reflector held with rubber bead;
. B, brass (chromium-plated) body;
. D, domed lens, although note that those fitted to the LBD 148 lights on Morgans were virtually flat, with a half moon pattern. The MBD light lenses were quite
heavily domed, with a vertical diamond pattern.
The suffixes on the lights:
. 140. Seven and a half inch aperture, six inch depth excluding lens;
. 148. Seven and a half inch aperture, seven and a half inch depth excluding lens.
Sidescreen mounting bolts of several designs appear to have been used, the most common being wingnuts (pre-war) and a bolt with a dished washer welded under the head (post-war). Errors Using the later chromed knurled knobs.