Chapter 3: Suspension
We continue our origins story in this edition with the story of the remarkably improved suspension in our Cobra.
Les tells us how it came to be...
Les was not happy with typical Cobra suspension in that it has a tendency to allow the car to nose-dive excessively under hard braking and squat at the rear excessively under hard acceleration. One does not want to remove all of this effect, as it is part of the seat-of-the pants sensation that is giving the driver feedback on what the car is doing, but it can be reduced to more reasonable amounts of movement with intelligent suspension design.
Les was also keen to stay away from the easier use of donor parts from other cars, as these are often unsuitable for use in a fast sports-car. This includes heavy BMW semi-trailing arms and McPherson struts, none of which would be found on a quality sports car such as a Ferrari or a Lamborghini.
The problem can be alleviated by lowering the center of gravity of the car and /or increasing the wheelbase. Doing the former is difficult and expensive (an all-aluminum engine block and dry sump system could be employed for example) and stretching the wheelbase by an amount which could make a noticeable difference would completely upset the aesthetics of the car.
The problem with building in anti-dive and anti-squat geometry into a car’s suspension is that it can introduce unwanted side effects, such as caster angle changes under braking. Les suspected that this could be avoided by moving over to compound angle suspension geometry, and with this in mind he approached Dr Andy Yates of UCT’s Engineering Department and asked for his assistance. Dr Yates wrote a software program that allowed Les to play with different suspension angles and to easily read off what was happening to the caster and other angles under load.
Eventually he arrived at a compound angle suspension system which offered the best results and modified his new multi-tube chassis to provide the correct mounting points, for his new double wishbone system. New welding jigs had to be made for the revised wishbones and fabricated uprights, and new larger alloy calipers which were matched to much larger brake discs front and rear. A well-known shock absorber manufacturer was approached to design and manufacture special coil-over shocks for the new suspension.
Test driving the new chassis proved that it now provided greatly improved high speed handling and road holding, with enhanced stability and a confidence inspiring ride.
In short, Les now had a world class Cobra with a modern chassis and suspension system under that classic Cobra body!
It was now time to address the other complaints which various Cobra owners had voiced over the years, and these needed to be tackled one by one.
How he did that will be covered in the next chapter of this story.