On our first acquaintance with the 9000 back in 7 November 1984, Autocar sat down with Saab's suspension expert, Magnus Roland, to find out how the car's innovative set-up could "prove that it is possible to have the best of both worlds: excellent stability and the progressive handling that appears to go hand-in-hand with a front-wheel-drive car".
Roland described the set-up of the 9000 as having a "side force oversteer" geometry and said that he could only have adopted it due to the "favourable dynamic index" of the car – its transverse engine layout, long wheelbase and minimal overhangs, with the powertrain and passenger area more within the wheelbase.
Autocar explained: "For Saab, handling has to be first-class on Tarmac but also provide the average driver with ease of control on the thousands of miles of gravel road in Sweden. Few must reach the limit on Tarmac, but almost all drivers must experience the car sliding at some time or another on gravel, and they certainly do on the snow and ice that grips Swedish roads for at least four months of the year.
"Roland says that one can have the unpleasant situation where initially good response soon turns to understeer, quickly followed by a nervous rear-end breakaway. Even the skilled driver may find certain front-wheel-drive cars difficult to balance in this situation. In a sense, one momentarily loses control of both ends of the car, while the car itself may be in an overall state of oversteer or understeer."
Roland, who was both "a theoretical and practical engineer and a top-class test driver", therefore recognised that what was needed was a system that would 'damp out' the small disturbances to enable the driver to control the car easily at the point of breakaway.
Drawing from rallying knowledge and mathematical modelling, he realised that "if one could reduce the slip angle between the tyre and the road in a bend – in other words, arrange the axle geometry to generate toe-out on the laden wheel, rather than toe-in (which many did at the time) – there would be a much softer build-up of a side force at the tyre, leading to a much easier car to drive on the limit. The total grip would be the same, but approached in a much more gentle way."
The difficulty was that "to 'buck the trend' and steer the axle in the same direction as the curve taken by the car also increases the attitude angle of the car, plus its response time to steering inputs, producing a reduction in stability". Clearly, "to overdo the rear axle steer effect would be absolute folly".
So, it was important to control the degree of axle steer accurately. Fortunately for Saab, then, it had "the most fundamentally locative and rugged rear suspension system around".