Haynes Roadster

Haynes Roadster is a replica of a Lotus Seven home-built car, according to the book Build Your Own Sports Car: On a Budget by Chris Gibbs (ISBN 1-84425-391-0). A Ford Sierra is used in the car as a donor for drivetrain and suspension components.

The Haynes Roadster is a follow-up to the Locost design described in a book by Ron Champion. Locost uses a Ford Escort Mark II as a donor, but as these have become increasingly rare, a design based on the more affordable Ford Sierra has been proposed. In contrast to Locost, which used Escort's solid axle at the rear, Haynes Roadster has independent, double wishbone, front and rear suspension.

The main part of the car is a space frame chassis. The chassis can be cut to size at home and built according to instructions from rectangular 25×25 mm and 19×19 mm mild steel tubes. It can also be purchased as a flat-pack kit with sets of tubes cut to size and ready for assembly at home or even pre-built by the supplier. Since the cars are hand built and the book design is often modified to some extent, each chassis is unique, but as a rough guide, it weighs around 700 kg when completed.

The suspension wishbones are fabricated out of cold-drawn seamless mild steel tubes. Sierra front uprights are used with some modification. At the rear, fabricated uprights support Sierra rear hubs.

The drivetrain usually consists of a Ford Pinto, CVH, or Zetec engine mated to a Sierra gearbox, a shortened or custom-made propeller shaft, a Sierra differential, and driveshafts. The book design is based on the Type 9 gearbox, but the list of chassis modifications to fit the bigger MT75 transmission is provided on the Haynes forum.

The braking system is taken directly from the Ford Sierra, except for the vacuum servo, which is not required for lightweight cars.

The steering system is often composed of a lengthened Ford Sierra steering column and a Ford Escort MkII steering rack.

The bodywork is a combination of GRP parts and sheet aluminum panels.