Classic components – brake light switches.

Nothing could be simpler than motorcycle brake light switches – or could it? Types include push/pull operation, lever action, buttons, hydraulics and more, but their function is simple; brake light switches must turn on the brake light when the brake/s ar

Requirements covering motorcycle brake lights is confusing worldwide, and the UK is no exception. Here in Britain, motorcycle brake light legislation has been introduced progressively, was sometimes retrospective, dates and/or requirements have been manipulated and there are exceptions. Advice is contradictory, but taking the MoT tester’s manual as a guide: motorcycles (arguably over 100cc) required a brake light on or after January 1, 1936 (previously dates in 1937).

There are detail changes to under 100cc capacity requirements but essentially if the machine cannot exceed 25mph or was first used before April 1, 1986, and is under 50cc, a brake light isn’t required.

Machines devoid of all lights do not require brake lights and likewise those which had had lights disconnected and lamps painted over or masked off. But individual MoT testers and police officers may be underwhelmed with a modern 160mph superbike devoid of all lights, including brake lights.

UK brake light switch legal requirements

All motorcycles including scooters, other two-wheeled vehicles and motorcycle sidecar outfits fitted with brake lights and manufactured/in use before April 1, 1986, require one brake light switch, usually fitted to the rear brake lever. Those after this date require a brake light switch fitted to every method of brake operation.

Types

There’s no legislation covering brake light switch operation types, except that it must work as described in the standfirst. Options include push/pull, lever, sliding, button, hydraulic pressure etc. Switches on offer and used by motorcycle makers work by making an electrical contact to complete a circuit, but switch operation varies, with some making the contact by pulling, sliding, turning or whatever the lever against a return spring, while for others release of the switch allows a spring to pull the electrical contacts together.

Brake lights

Although outside the remit of this feature, it is worth remembering the brake light bulb filament must give a considerably brighter light than the tail-light. As we know, some rear lights employ double filament bulbs, others use two separate bulbs. Often, these are supplied in six and 12V form, with 5W tail-light and 21W stop light filaments. But for machines from the late 1930s through to the 1950s, the 6V bulbs employed would have filaments in range 3-5W rear light, to 10-18W stop light, so, for example, 3W rear light and 10W stop light.

Lucas types 1936-57

In this period Lucas offered five brake light switches, four slider models and one lever action (31668 - 3SA with protective boot 360363) which was a new introduction for 1957 and initially fitted to the then recently launched Triumph Twenty-One. Variants of the SA design were later introduced e.g. 6SA fitted to the 1962-70 BSA A50/A65 unit twins.

Of the slider models, two (31281 54C and 31383 22B) mounted with screws/short bolts to the frame and the remaining duo were mounted to a frame rail with a clip fitting. The clip fitting models could be retro fitted to many motorcycles, and, for this purpose as well as original figment, Lucas offered five spring lengths, from 1⁄ inches to 7¼ inches. The universal type brake light switches available today from every motorcycle shop and autojumble can be used similarly.

* Lucas has been taken as an example – other makers, including Miller, Wipac and aftermarket parts suppliers, offered ranges of brake light switches, too.