With its stripped-out interior, the Mk1 Elise made a feature of the anodised aluminium used for its structure and in so doing set a new standard.
Anodisation is an electrochemical process that creates a surface that, with a little extra work, can be bonded to another. But it was its decorative function that first attracted Lotus, not its bonding qualities. “It came about because we wanted to get rid of the interior of the Elise to save weight and cost,” creator Richard Rackham told us. Anodised aluminium gave it a cool, race car-like look.
Lotus then looked for a glue for bonding anodised aluminium and found one that Ford was using to stick oily steel together. It worked and has now become almost an industry standard, to Rackham’s surprise: “It seems everyone sort of got tunnel vision on something that we went scattergun on.”
What makes the E-Sports special?
A new aluminium alloy developed by Brunel University is a major contributor to the weight saving. It’s stronger so can be made thinner.
The Emira’s engine sits on a subframe to isolate vibrations, made of heavier welded steel instead of bonded aluminium because the heat of the engine could melt the glue. However, the electric drive unit of the E-Sports platform is attached directly to the aluminium rear structure by special mounts. The battery box is designed as part of the structure, saving weight.
Gluing aluminium parts together no longer needs heat to complete the bond, cutting emissions in the manufacturing process. Welding aluminium is tricky, because it distorts in the heat, but that issue is reduced with the pulse- welding method, which reduces the number of bonds and rivets needed.
Lifting the drive unit creates space for a large rear diffuser, creating the downforce that would else have to be supplied by a big, drag-inducing wing.
The Elise’s double-wishbone arrangement has been replaced by a multi-link set-up made of lightweight, hollow parts that reduce road noise.