Mini John Cooper Works WRC: the roll cage in detail

Mini claims it’s created the safest WRC car ever – with a little help from Prodrive.  And to prove the point, they’ve opened up the Mini Countryman WRC’s innards and spilled some of the secrets of its rollcage.

The Countryman racer is stripped and fitted with a new type of rollcage designed by Prodrive. Its beams curve outwards and the Banbury engineers say it has been designed to withstand impacts much better than the straight crossbeams used in most WRC cars.

It’s all about the curvature of the rollcage members. Prodrive says it’s like curved body panels being stronger than flat ones; the slightly bowed bars of the rollcage give it extra strength, and the loads are fed into welds in a controlled direction to reduce the risk of rollcage failure by tearing.

The new Prodrive rollcage design also increases interior space – always welcome in a Mini – and has better crumple properties in a crash.

‘The Eureka moment was the redesign of the side impact protection bars, routing them farther away from each crew member and subtly changing their shape,’ said Dave Wilcock, Mini WRC’s tech director. ‘In an impact, this brings the structure into play much sooner, allowing softer materials to be specified to safely decelerate the crew over a much longer period of time.’

The new door beams are welded through the Mini Countryman WRC’s B-pillars to strengthen the shell too.

A side impact is the most dangerous type of shunt – not just in rallying. There is little room between the impact and the driver/navigator, so whatever hits the car could hit them too.

Prodrive subjected more than 50 rollcage samples to limit-finding tests to find a design that worked best. The company says the result is strong enough for the FIA to consider making such a cage mandatory in future designs.

By Jack Constantine