Audi's magnetic appeal

Glynn Tulloch says the magnetic suspension system will allow Audi and other car manufacturers more flexibility to vary the mix.

The growth of electronic components in vehicles in the past 30 years or so has influenced many of the electronics industry's development programmes.

Groundbreaking safety devices such as airbags, anti-lock brakes, and stability control kept the electronics industry on an automotive course. So did satellite-navigation programmes.

But the need for carmakers to adapt quickly to match the expectations of buyers means the automotive industry no longer wields such influence.

"We've been left behind in the dust by cellphones, by personal digital assistants, and so on," says Jeffrey Owens, president of US company Delphi Corporations's electronics and safety divisions.

Delphi is a major automotive parts supplier.

It developed the magnetic suspension system used by Holden Special Vehicles in the GTS and Senator sedans and for Audi in its new TT.

Owens told a conference in Detroit that automotive demand in the 1970s accounted for about 70 per cent of the computer-chip market in the United States. The chips were needed to drive solid-state ignition systems and engine-control units.

"But now there is a vast market for computer chips for portable devices," Owens says.

"De facto standards for such things as processing speeds and microchip architecture are being set without considering automotive applications.

"This causes difficulties when popular consumer devices, in demand for automotive use, are no longer compatible with the electronic architecture of vehicles."

Owens says carmakers are waking up to consumer needs. "But there is still room for improvement.

"A five-year-old PC has USB access ports that plug in and play the latest consumer devices. Five-year-old cars don't.

"Clearly, if we enable it or not, it's going to happen in the vehicle.

"We can provide the solutions to reinvent this industry - but only if the original equipment makers and the suppliers work together."

The magnetic suspension system is an example of that. Delphi went back to school science to develop it, using a magnet and iron filings. Then it went to General Motors to adapt it to cars.

The way the magnet draws iron filings together is roughly what happens in the shock absorbers of the Holden Special Vehicles cars and the Audi TT, the first two nameplates to use the system in New Zealand.

HSV calls it magnetic ride control, or MRC. Audi doesn't have an acronym.

Conventional shock absorbers contain oil to control the up-and-down movement of the wheels. Valves and pistons regulate the flow for the best ride.

The magnetic system uses a synthetic magneto-rheological oil in which teensy-weensy iron particles - much smaller in diameter than the width of a human hair - float about at random.

A magnetic field changes the oil from a free-flowing liquid to a syrup, depending on dynamic forces. The driver can select cruising or performance modes, too.

In a nutshell, sensors measure the up-and-down motion of each wheel and tell electrics in the shock absorber when to act.

On a smooth, straight road the iron particles are pretty much left to do their own thing in free-flowing oil, but under cornering forces, for example, they get zapped by the magnetic field and jump into line to change the consistency of the oil to that of molasses or peanut butter to firm up damping. It is this continuously variable damping force that adapts to changing road surfaces without the delays of conventional mechanical systems.

Delphi says the system is the automotive industry's fastest-acting suspension, fine-tuning the ride every thousandth of a second. That's about once every three centimetres of wheel rotation.

The Ferrari 599 uses it. Audi's new R8 supercar is expected to come with an improved version next year.

The Audi TT with the magnetic system has two ride modes, "normal" and "sport", activated by a button on the centre console.

In normal mode the oil is more free-flowing and the degree of damping less pronounced. In sport mode it becomes less free-flowing and the car hunkers down on the road. Steering response is improved.

The magnetic ride is standard on the all-wheel-drive 3.2-litre V6 Audi TT and optional on the front-drive turbocharged 2-litre version. Both models come with the choice of six-speed manual or six-speed S-tronic sequential gearboxes.

The V6 quattro produces 184kW (250bhp) at 6300 rpm and 320Nm of torque between 2500-3000rpm. It retains a 90:10 front-drive bias but can split drive to a maximum 50:50.

The 2-litre delivers 147kW (200bhp) between 5100-6000rpm and 280Nm between 1800-5000rpm.

The sports coupe is a space-frame design with a mix of 69 per cent aluminium and 31 per cent steel, a combination that Audi NZ general manager Glynn Tulloch says is the way of the future. "It will allow Audi and other car manufacturers more flexibility to vary the mix, depending on cost restraints and how they want to shift weight around the car."

The TT is lighter, stronger and bigger inside and out than the outgoing model.

It is a better drive, too, a much improved car all round. Room in the rear will always be cramped. The 2-litre manual costs $79,500, the automatic $83,500. The V6 manual is $100,900, the auto $104,900.


Audi TT

Power: 3.2-litre v6 or turbocharged 2-litre four-cylinder
Drive: V6 all-wheel-drive quattro, 2-litre front-drive
Gearboxes: 6-speed manual or 6-speed sequential S-tronic
Wheels: 2-litre 17in, V6 18in
Suspension: Macpherson strut front, multi-link rear
Size: 137mm longer, 78mm wider, 6mm higher