Audi TT : Lightweight Aluminum Body And Improved Suspension

Completely new, the Audi TT sports car follows on the theme adopted by most big car makers with new models. Bigger means better, and garnish the dish with an upgraded interior. The coupe is available now, with the roadster set to follow soon.

Despite following the up-sizing path, the new Audi TT sports car breaks the mold. It has a body structure made mostly from aluminum, so the new car is lighter than the old one ? not many makers can make that boast.

This is an important move. Prior to the development of this model the VW Group was wedded to the use of a range of standard under bodies for different marques of the same size? A3, TT, VW Golf and Seat Toledo for example. Now, the designers of the different marques have more freedom in combining standard units with special ones where they can justify it.

The Audi TT is the first example from the VW Group reflecting the new freedom, and the result is a big improvement all round. Audi was able to do this because it has been making bodies based on its ASF concept of a frame of extrusions and castings for over ten years.

New sculptured look for longer body

Clothing this new structure ? little short of revolutionary in this class ? is a new body with elegant lines. The stylists have certainly done a good job in stretching the TT out a bit to gain a new grown-up look.

At the front, there is the obligatory deep grille found on other Audi cars, but this one is flanked by wide air intakes. The sides are somewhat similar to the old model, but with sculptured lines producing highlights. This makes the car look completely different, yet it is recognizable as a new TT. To improve aerodynamics, there is a spoiler that pops up at 120 km/h (75 mph).

The interior is also new, but still has many aluminum features in the trim. The center console slopes up toward the dash, the gear lever protruding from the sloping face, where it is right beside the wheel. There is a smart new steering wheel, just 14.3 inches in diameter, with a lightweight magnesium rim flattened at the bottom.

More important, the seats have been lowered, to give more of a sporty feel and to lower the center of gravity, which will improve cornering.

Audi TT Aluminum structure

The main innovation is in the body structure which has an aluminum space frame similar to that on the Audi A8. However, in this model there are a number of steel panels ? mostly at the rear. These make up about 30% of the body weight, and provide the rear structure.

Like the A8, the main structure of the Audi TT is made of aluminum extrusions, precision castings and sheet. However, the doors, rear floor, trunk lid and other panels at the rear are made from steel sheet. This is a bit odd, and no doubt results from cost-cutting exercises, as the trend among some competitors is to combine steel structures with aluminum doors, trunk lids and hoods.

Castings are used for the brackets and parts of complex shape, such as the door pillars. The castings are generally welded to the hollow extrusions used for the sills and main members, but various other fasteners are used, including punch rivets bonding and special fasteners.

Audi says that the use of the aluminum frame results in a reduction of 48% of body weight, while the torsional stiffness has been increased by 50%. Sounds good. Of course, the weight reduction is much less for the car as a whole, but is still fairly impressive. The new 2.0 liter model weighs 2,775 lb, which is a weight reduction of about 375 lb (170 kg). Not many makers of sports cars reduce weight at all with new models, and certainly this sort of weight reduction is rare.

Audi TT 2.0 or 3.2 liter engine

The new Audi TT coupe is powered by either a 2.0 liter turbocharged direct injection engine, or the 3.2 liter V-6, giving 200 and 250 bhp. That?s more or less the same as before. In fact, the 2.0 liter unit is similar to that in the VW Golf GTI, an excellent engine, which develops 200 bhp at 5,100 rpm and holds that power up to 6,000 rpm. Maximum torque of 207 lb ft (280 Nm) is produced over a wide range - from 1,800 rpm up to 5,000 rpm.

However, previously, the best four-cylinder TT was the 1.8 liter 240 bhp model, so it is to be hoped that a 2.0 liter 250 bhp is on the way. The alternative is the compact but rather heavy 3.2 liter V-6, which develops 250 bhp at 6,300 rpm with maximum torque of 236 lb ft (320 Nm) at 2,800 to 3,200 rpm. In the previous model, the performance wqas not as good as the hottest four-cylinder.

Both are coupled to six-speed manual gearboxes with the option of the S-Tronic (DSG on Volkswagen) twin clutch automatic/sequential manual box.

The four-wheel drive system is standard for the V-6, but front-wheel drive is what you get with the 2.0 liter. This system is developed from the previous model, with a multi-plate clutch at the rear transmitting power to the back wheels according to requirements.

Normally, the new system sends 85% of the power to the front wheels, and 15% to the back? an improvement over the 95/5% split on the earlier model, but still not really enough power to the back wheels for a sports car.

Suspension and brakes have also been improved, the front strut system benefiting from a wider track and improved geometry, while weight has been reduced owing the use of the aluminum links.

At the rear the torsion beam axle has given way to a multi-link system similar to that used on the Golf. This gives better control of camber and toe-in.

Audi TT new adaptive damping

When they are vertical, the damping is soft, and as they are turned, so the damping stiffens up. The beauty of this system is that the damping rate can be changed instantly to suit conditions, so you can have soft damping which stiffens up as soon as you enter a corner.

Brakes are larger than before, and 16-nch wheels are standard on the 2.0 liter model, and 17-inch wheels on the 3.2. However, 18 and 19-inch wheels are available.

As I pointed out right at the beginning, the new Audi TT is bigger than the old one? 5 inches (137 mm) longer than its predecessor at 164 inches (4,178 mm), and 3 inches (78 mm) wider. It has more room for the driver and passenger, and more space for luggage. More grown up in fact, but without the penalty of extra weight that usually goes with a larger car.