Driving experience tuned for quick, nimble performance on the road or track
DETROIT – The 2013 Cadillac ATS delivers a driving experience that advances the brand’s performance legacy with a balance of racetrack-honed control and uncompromising refinement.
That experience is supported by new chassis and suspension systems, excellent power-to-weight ratios across ATS’s power-dense powertrain lineup and a robust body structure that enables finer chassis tuning and greater crash protection.
Video: Cadillac ATS 2013
https://www.youtube.com/watch?v=CjcaZcvHu3k
Highlights of the chassis and suspension features include:
- Cadillac’s first five-link independent rear suspension, using high-strength steel and efficient straight link designs
- A multi-link, double-pivot MacPherson-strut front suspension with direct-acting stabilizer bar
- Driver-adjustable FE3 sport suspension with Magnetic Ride Control real-time damping
- Premium electric variable-effort steering gear by ZF Steering Systems
- Four-channel ABS with available Brembo performance brakes
- Available all-wheel drive.
Before selecting even the first fastener, engineers launched targeted research projects that helped determine the best design and optimal geometries for the front and rear suspensions. Early suspension prototype vehicles were constructed and tested in diverse environments, before complete ATS prototypes hit the pavement at GM’s global proving grounds, as well as highways and racetracks around the world.
“ATS engineers built on the legacy of the acclaimed CTS-V Series and picked up the challenge of well-established competitors to create an American sports sedan to rival Europe’s finest,” said Chris Berube, lead development engineer. “More than the roster of its chassis components, the ATS’s driving experience is derived from the whole of the car – a low curb weight, optimal balance and excellent dynamics refined during countless hours of racetrack testing.”
Proportion and balance are definitely on the ATS’s side, with a low curb weight of less than 3,400 pounds (1,542 kg) and power-dense powertrains that are also lightweight to achieve a 50/50 weight distribution and a greater power-to-weight ratio. They complement wide front and rear tracks – 59.5-inch/1,512mm (front) and 60-inch/1,548mm (rear) – for a lower center of gravity that promotes greater stability.
The low curb weight also helped engineers optimize performance by not having to go big on components that contribute to unsprung weight, including the wheels, tires and brake components.
“A heavy car needs larger wheels and tires and larger brakes to account for its overall mass,” said Berube. “With the ATS, its low weight meant we didn’t have to spec the largest wheels and brakes in the segment – the performance is among the best in the segment with smaller, optimized parts that save weight and enhance efficiency.”
Low vehicle mass and optimal brake sizes are expected to give the ATS’s braking performance that is among the best in the segment, with Brembo brakes contributing to 60-0 performance of approximately 129 feet (39.3 meters).
A strong body structure is the backbone for the ATS’s driving experience. It ties the chassis and suspension elements together with great stiffness that enabled a higher degree of tuning precision.
“This is a rock-solid architecture that supports a rock-solid driving experience,” said Berube. “But even the stiffest body can’t ensure great ride and handling. That comes from an optimal suspension geometry and advanced damping control – and the ATS packs both.”
Dual ball joints, five links and a limited-slip diff
Up front, a multi-link double-pivot suspension – based on the MacPherson strut design – is used for a more precise feeling of control, including more linear and communicative steering, and a smoother ride. It also improves impact isolation on bumps and rough surfaces.
The double-pivot system incorporates a pair of ball joints and lower control arms – one in tension and the other in compression – to replace a conventional wishbone at each wheel. The control arms, the spindle and the body form an effective four-bar link for each side of the front suspension, creating virtual pivot points for greater camber control. There is also a direct-acting stabilizer bar.
The front suspension’s design also enables a longer spindle, larger pivot center and positive-offset steering geometry for optimal steering control, excellent straight-line stability and a more refined ride. High-durometer rubber and hydraulic bushings are used with the front suspension for an excellent balance of ride comfort and precise response when corning.
“The kinematics of the ATS’s front suspension are more complicated, but the payoff is worth it in the way the car drives,” said Berube. “The driver will feel directly connected to what the front wheels are doing, but with a comfortable degree of isolation that makes the ATS a great touring car for long drives.”
At the rear of the ATS is the first five-link independent suspension in a Cadillac. It’s a design that helps reduces roll center motion, enables positive lateral control, reduces “squat” during acceleration and promotes excellent dynamic stability. In short, it helps keep the tires planted on all surfaces and during all hard-cornering maneuvers.
Four handling links (upper and lower control arms) are used at each side to control wheel motion and a toe link at each wheel provides additional horizontal control – particularly during hard cornering. The upper and lower links create an effective double-wishbone design, although the links are mounted independently.
As with the front suspension, the five-link design creates virtual pivot points that the ATS’s engineers used for geometry optimization. The stiff links are mounted on a cradle that contributes to a smoother, quieter and more isolated ride. The cradle is made of steel (with hydroformed side rails) to help optimize the car’s structural stiffness and mass.
“Using an aluminum cradle would have reduced the ATS’s overall weight, but we found a few extra pounds at the rear suspension helped get the front/rear weight balance closer to the optimal 50-50 ratio,” said David Masch, ATS chief engineer. “We also added mass to other areas of the car where it was necessary to achieve performance.”
Seventeen-inch (17×8-inch) wheels used with 225/40-series tires are standard and 18×8-inch wheels and 255/35-series rubber are offered on the ATS, with run-flat tires. Models with the FE3 suspension feature 18×9-inch rear wheels.
A mechanical limited-slip differential is a feature not matched by all other competitors and gives the ATS an edge when it comes to ensuring all of the powertrain’s torque is applied to the tires during hard cornering. It is standard with the six-speed manual transmission and included with the FE3 sport suspension package. It is housed in a robust 8.6-inch carrier. Other models feature a 7.67-inch carrier.
MRC, electric power steering and other advanced control systems
Supporting the ATS’s new suspension designs are advanced damping, steering and braking systems, including Magnetic Ride Control.
Magnetic Ride Control (MRC) is the heart of the FE3 Sport Suspension package, which is included on the Premium Collection and also includes a mechanical limited-slip differential, high-capacity cooling system and 18-inch summer-performance tires. MRC is a real-time damping system that delivers more precise body motion control. It “reads” the road every millisecond and can change damping in only five milliseconds.
With MRC, the conventional mechanical-valve shocks and struts are replaced with electronically controlled units filled with a magneto-rheological fluid, which contains minute iron particles. Under the presence of a magnetic charge, the iron particles align to provide damping resistance almost instantly. Sensor input determines the amount of resistance required, varying the magnetic charge to optimize damping.
Adjustable settings for the FE3 suspension allow the driver to select different ranges of damping for Magnetic Ride Control, including a competitive mode that also adjusts the intervention of the stability control and traction control systems.
All ATS models come with a premium electric, variable-assist power steering gear from ZF Steering Systems. It is designed to deliver excellent response and on-center characteristics, while also saving fuel because engine power isn’t directly required to assist gear movement – as is the case with conventional hydraulic systems.
The steering gear has great torsional stiffness and lower operating friction, which enhance the steering feel with almost perfect linear response. Additionally, the steering column and intermediate shaft feature stiff, direct-acting and low-friction ball bearing designs. That means there is almost no “lash” in the entire steering system, for a more immediate and connected-to-the-road feel for the driver.
Four-wheel disc brakes are standard on all models, with Brembo performance brakes available on the standard model and included on the Luxury, Performance and Premium collections. They are matched with a four-channel ABS system that is integrated with standard StabiliTrak stability control and full-function traction control.
All-wheel drive is available, for even greater traction assurance on wet and icy road surfaces.
