With a front track widened from 61.7 inches to 62.4 inches, the independent front suspension uses cast-aluminum unequal-length upper and lower A arms that reduce unsprung mass and enhance handling and dynamic wheel control. For 2013, the suspension has been thoroughly retuned with new Bilstein® aluminum-body shocks, spring rates and hollow front- and rear-stabilizer bars.
The rear suspension includes cast-aluminum, unequal-length, upper and lower A arms, toe-control links and coil springs. Rear track is 61 inches (1,550 mm).
Viper GTS uses new gas-charged, monotube Bilstein Damptronic Select aluminum-bodied shock absorbers with large 46 mm pistons. The new two-mode shocks have street and track settings, selectable through a switch on the console. In street mode, the shocks are designed to provide a compliant ride, while still providing damping levels appropriate for the extreme capabilities of the SRT Viper GTS; race mode goes all out.
Spring rates on the base Viper’s passive-shock package have decreased 5%, while spring rates on the Viper GTS model’s Damptronic package have increased 5%.
Both front- and rear-stabilizer bars are hollow for weight savings and are 27 mm in diameter. The rear suspension has been re-engineered with the relocation of the rear-suspension toe-link, moved from behind the rear-axle centerline to in front of the rear axle. The inner pivot of the link uses a tuned bushing to manage rear-toe compliance with respect to lateral load. Overall, the suspension has been retuned to enhance stability and make it easier to “toss” the Viper into turns.
Four-piston Brembo brakes with fixed-aluminum calipers with 355 mm x 32 mm vented rotors are used in each position. Pistons are 44 mm/40 mm, opposed, and brake calipers are forged and weight optimized by fully machining all surfaces. The calipers are among the stiffest available with distortion from heat nearly eliminated even under the most demanding braking conditions. Total swept area of the brake system is 603 square inches spread over all four corners.
The new master cylinder and power-brake booster for 2013 moves from a front-rear split to diagonal-split hydraulics.
For the first time the SRT Viper models will include both electronic stability control (ESC) and traction control systems. The ESC system is a four-mode setup with speed sensors at each wheel along with a yaw sensor, lateral G and steering-wheel angle sensor. The system is track capable in all modes, including “Full On.” On GTS, two graduated levels of stability and traction control are available in addition to “Full Off” to progressively reduce the amount of assist, as driver skills and confidence are gained.
With the system in Full On, drivers receive the maximum benefits of both the traction control system and stability control without unnecessary intrusion and the full cornering capability of the vehicle is realized. Sport mode allows more longitudinal and lateral slip before the traction control and stability control system are engaged.
For competition, the Track mode has no traction control while the higher limits of Sport Mode stability control are maintained. In Full Off mode, both the traction control and stability control are disabled with the anti-lock braking system (ABS) remaining active. A steering-wheel mounted button enables the driver to select the optimal mode depending on road conditions or preference. A telltale graphic in the instrument cluster advises the driver which setting is activated in the ESC system.
There are seven part numbers for wheels, and Pirelli is supplying tires, 355 in the back and 295 in the front, with a unique compound front to back.
Wheel sizes are 18 inches by 10.5 inches up front and 19 inches by 13 inches in the rear. The new wheels are 16 pounds lighter, cutting unsprung mass. The five-spoke, forged-aluminum “Rattler” wheel design on the 2013 Viper model is available with fully polished (standard), glossy black, or low-gloss black finishes. The Viper GTS has a split six-spoke forged-aluminum ‘Venom” wheel design with three available finishes including polished face with graphite-painted pockets (standard), fully painted hyper-black or fully painted low-gloss black.
Specially formulated, Pirelli P-Zero Z-rated tires are new; up front, tires measure P295/30ZR18, while rear tires are P355/30ZR19. The new tires have improved lap times and skidpad grip, with better cool and wet weather performance and better road feel. (The compound includes silica and carbon black molded into an asymmetric, wide rib tread design which resists deformation).
New steering gear for the hydraulic rack-and-pinion system has better road feel, on-center precision, and effort gradient as cornering loads increase. Steering ratio is 16.7:1 with 2.4 turns required lock-to-lock.
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