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, Sat, 1 Dec 2001 18:43:49
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This is a press release put out by Saab. From what I read, I'm sure the 02 models are better handling. I allways thought the steering on my 01 base model is a little vague and the balance of the car a little off, as if the rear end is to light. I notice it particularly when driving on snow, which was not the case with my venerable 9000T. This being said, the 9-5 is far superior to the 9000 IMHO.
July 4, 2001
A sharper chassis for a sportier Saab
With the new Saab 9-5 range's looks there comes a new driving experience. The new 9-5 has suddenly got sharper. Sharper in the way it steers; more positive in the way it handles. The result is an exhilarating and communicative drive with the emphasis strongly on Saab's sporting character.
The key changes have been made at the front of the car to render it more reactive and quicker-witted. The overall balance front to rear has also been honed to give the new Saab 9-5 range a flatter, more consistent handling characteristic, while also eliminating cornering pitch.
"We looked at what we had achieved with the Aero - which seems to have been universally liked - and then applied that car's sportiness to the rest of the new Saab 9-5 range," comments Sonny Bergman, head of vehicle dynamics. "But we also took the opportunity to upgrade the handling and performance characteristics of the Aero model at the same time. After all, there's always room for improvement."
Bergman and his team concentrated on improving the car's front-end responsiveness and flattening out the pitch-induced roll during hard cornering. So the front springs have been stiffened by 10 per cent, while the diameter of the front anti-roll bar has been increased by 1mm on all models.
The damper settings have also been changed to accommodate the increased stiffness of the front springs and provide firmer control of the car's balance and poise during cornering. Naturally, there are minor variations in spring and damper rates to allow for the differing weights of the new Saab 9-5 range's various powerplants, but the behaviour has been designed to remain consistent from model to model.
The upper strut mountings have also been strengthened to improve longitudinal rigidity and better lateral load response. Once more, this benefits a sportier driving characteristic at the expense of some ride compliance, but more in keeping with the new 9-5's sporting ethos.
Stiffer front subframe lightens the load
The front subframe, used to isolate road shocks more effectively from the driving compartment, has received a significant upgrade, too. Like the springs, the subframe has been stiffened, but it has also been lightened to accommodate the extra weight of the new V6 turbo diesel engine.
The steering rack, which is located at the rear of the front subframe, has been changed to match the more effective handling characteristics resulting from the spring and damper changes. New, longer steering arms are coupled to the existing steering rack. While initially lowering the gearing, it works more effectively with the sharpened front-end chassis modifications, offering a greater degree of driver confidence, comfort and control, while still providing excellent feedback.
Stiffening the front torsion bar and retuning the steering valve gear has further enhanced steering feel. Although this means less steering assistance in the straight-ahead position, it greatly benefits steering feel. This means the driver is constantly aware of what is passing beneath the new Saab 9-5's front wheels for enriched driver/chassis information interaction.
The other change to the steering system concerns the steering knuckle, which is now made from aluminium, for reasons both of lightness and of strength - as with the subframe. "We wanted to give the same performance characteristics throughout the range, but that also meant accommodating the extra weight of the new turbo diesel engine, despite its aluminium construction and compact nature," comments Sonny. "That necessitated lightening as many items as possible within the engine bay so that the engine's extra weight was neutralised. However, we did benefit from the engine's size. It meant we could package it low down, which contributes to the sporty handling of the diesel."
Retuned rear suspension, too
However, Sonny and his engineering team also turned their attention to the rear end of the car. The same spring and damper changes incorporated into the front suspension have also been applied to the rear suspension set-up.
"It has made a big difference," says Sonny. "The rear end used to 'float' too much. These spring changes make the back end respond more quickly and more consistently. You'll notice less movement in the back, especially in the V6 petrol model. The ride's firmer but the pitch has gone."
The multi-link suspension at the rear is also mounted on a separate subframe. It's attached to the rear body structure by four large-volume elastomer bushes. To increase the responsiveness at the rear, the bushing in the system's trailing-arm set-up has been stiffened. Again, the benefit is a more responsive and sharper-handling chassis.
The final changes concern the four corners - the wheels. There's a new generation of Michelin tyres that have been specifically tuned to the requirements of the new Saab range. These are available in 15-inch, 16-inch and 17-inch sizes along with an all-weather tyre. The new tyres provide better stability and dead-centre feel, while also contributing to the chassis's improved turn-in and lack of understeer.
Twelve go testing - from Arizona to the Arctic Circle
Sonny has overseen the 18-month development process with 11 other engineers. Three have been working on the steering feel, two on the engine mounting points, and six on the basic chassis parameters - such as tyre compatibility and shock-absorber rates.
Initial testing was carried out at one of GM's US test tracks at Mesa in Phoenix, Arizona, followed by time in the ice and snow of the Scandinavian Arctic Circle. Since last autumn, the team has been honing the final touches to the car in Spain.
Benchmark cars to assess the Saab's progress included the Audi A6, BMW 5-series, Mercedes-Benz E-class and Volvo's S80 model. Each was assigned a parameter the Saab had to beat. For example, the new 9-5 range had to beat the 5-series on steering feel; the Volvo on comfort; and so on.
"I think you'll be impressed with what we've achieved," says Sonny. "The steering, in particular, is excellent, which is matched by much better handling and a sportier ride. The car now feels like a smaller car to drive. It's more agile, more sporty.
"Yes, we've given it a very sporty flavour. I think you'll like it!"
Chassis improvements - key points
* Improved chassis control from Linear through to Aero models
* Better and more responsive steering feel
* Revised suspension settings and thicker anti-roll bars for sharper handling
* Sportier ride and performance characteristics
* Stiffened front subframe
* Pitch and roll dialled out for flatter, more neutral cornering behaviour
* New-generation Michelin tyres tuned specifically for new Saab 9-5 range
posted by 207.96.2...
, Sat, 1 Dec 2001 18:43:49
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