Production, suppliers and identification

• Assembler: Hoover plc, Merthyr Tydfil (Pentrebach), South Wales. C5s were built in building MP7, a separate new 40,000 sq ft hall connected to the main washing-machine factory by a tunnel.
• Line capacity: two lines at about 50–56 vehicles an hour. Hoover quoted up to 8,000 a week and 200,000 a year. Hoover's own service planning assumed 4,000 a week.
• Assembly time: about one man-hour per vehicle.
• Chassis: two Lotus-designed steel pressings from Willenhall Manufacturing (West Midlands) were spot-welded automatically at Hoover and painted to pass a 90-hour salt-spray test.
• Body: the two polypropylene mouldings were joined by resistance tape welding. An electrically heated tape goes round the rim of the lower half, the halves are jigged together, and the current is switched on for about 70 seconds. The weld line is hidden under the yellow reflective stripe. Completed shells went by overhead conveyor to a “marriage station” and were bolted to the pre-assembled chassis and drive unit.
• End-of-line test: a rolling road with a mechanical arm simulating the driver's weight. It checked motor no-load and stall current, stall protection and reset, the load indicator, the battery gauge, pod current draw and the brakes.
• Packing: each C5 was boxed in a large carton with the charger, tool kit and literature, and loaded straight onto container lorries. Distribution centres were at Hayes (Middlesex), Preston and Oxford.

The launch magazine C5 Driver (Jan 1985) carries adverts from suppliers that confirm their roles:

• Polymotor Italiana S.p.A. (Casella, Genoa; Philips group): “designer and manufacturer of the electric vehicle motor”.
• Mikron (UK) Ltd, Kirkheaton, Huddersfield: “designed and supplied the gearing system”.
• Lin Pac Mouldings: upper body, lower body and boot mouldings.
• J.J. Harvey: made the models and mould tools, using four steel blocks weighing 45 tons in total, finished by spark erosion.
• AB Electronic Products Group, Abercynon: electronics.
• Stellar Components, Maldon: chargers. SinclairC5.com credits the design to “Selmar”.
• Oldham Batteries, Manchester: battery.
• Bowater Containers: the box.

• The upper shell weighs about 5.5 kg and the lower about 4.25 kg. The Engineer called it the largest injection moulding of its type in mass production.
• Drag area (C_d·A) is about 0.23 m², from Exeter University wind-tunnel work.
• The colour is moulded in, so scratches don't show a different colour underneath. The body needs no polishing.
• The body is mounted on the chassis with four bolts and rubber bump mounts. There is no separate suspension; ride comes from chassis flex, the mounts and the tyres.

• Vehicle serial number plate: item 18 on the handbook's “Know your vehicle” diagram. The handbook asks owners to record the serial number, master-switch key number, battery serial number and charger serial number.
• Examples:

• No published key to the serial-number format has been found. Can you help? If you own a C5, please add your serial number, the colour of your boot lid and motor housing, and any date stamps to a community register so the numbering can be decoded.
• Features that help date a C5:
  • Boot lid: grey on early and pre-production vehicles; white on later production.
  • Motor end assembly: brown plastic on early motors (brittle); pale yellow/white on later ones.
  • Retrofits: a motor support bracket or metal retaining plate, the chain-tensioner rework, a rear brake heat plate.
  • Second-battery hole: some C5s (“original 2-battery machines”) have a square cut-out in the right-hand moulding with a grommet, for the second-battery wiring.
  • Harness: the standard harness or the “alternative” one (a 6-connector cluster under the tunnel).
  • Lotus prototypes are GRP (fibreglass), not polypropylene, and differ in dozens of details. Examples include hand-cut decals, a 6-spoke front wheel, 35 psi tyres, a blue metal control box and a toggle main switch. See John Dunne's “Lotus C5 prototype” article on c5owners.com.
• Unsold-stock and boxed examples still turn up. They usually come with a sealed handbook, charger and tool kit.

• About 2,500 had been built by the launch. Total output was about 12,000 (RCAHMW, Twist & Go) or 14,000 (Wikipedia, citing the receivers and the press).
• About 4,500 were sold by Sinclair Vehicles before receivership. Ellar (Surplus Goods) later sold nearly 7,000 more.
• Production ended in August 1985.

• The Engineer, “Sinclair C5 trike takes to the roads”, 17 Jan 1985, pp. 36–37 (scan on c5owners.com).
• The Unofficial Sinclair C5 Service Manual, “Manufacture and Test”.
• Frank Clements' recollections (c5owners.com); Museum Wales object records; RCAHMW, “The Sinclair C5 & Merthyr Tydfil”; Wikipedia.