Mustangworld: The 2000 Cobra R

The engine is mated to a Tremec T-56 six-speed manual transmission, the first time any Mustang has been equipped with a six-speed gearbox. The transmission provides closer ratios for racing, as well as the robustness necessary for the engine’s torque. It is fitted with a special mounting bracket and reinforcement system for extra strength and stiffness.

Cobra R’s interior reflects the car’s high-performance capability. Recaro seats provide the firm lateral support that is essential for drivers subjected to the high g-forces of racing. Cobra R’s B&M Ripper shifter gives drivers the advantages of short throws and positive stops, and also provides added durability for the rigors of racing. The shift lever is topped by a leather-wrapped knob embossed with the six-speed shift pattern. In the instrument cluster, a 180-mph speedometer sports the Cobra R emblem. In the rear, the seat has been replaced with a closure panel that covers the floor pan. The area is covered by carpet that extends up the back and is held in place with velcro.

The clutch is the 11-inch single plate unit used in the Cobra, which in durability testing proved capable of handling the horsepower and torque of the Cobra R engine. Visteon supplies the Cobra R’s hydro-mechanical differential with speed and torque sensitivity. For racing demands, it provides predictable performance and greatly improved torque transfer capability. Speed sensitivity is achieved with a gerotor pump, which is activated when the half shafts rotate at different speeds.

When this happens, the pump applies hydraulic pressure through a piston to compress the clutch pack, transferring torque to the other wheel. The differentials torque sensitivity provides immediate torque transfer, which is very helpful in maintaining grip during straight-line acceleration. When one wheel spins relative to the other, the differential’s beveled helical gears produce an axial force that tries to separate them and, like the gerotor pump’s action, compresses the clutch pack to transfer torque. The final drive ratio is 3.55:1, compared with the Cobra’s 3.27:1. The rear axle half-shafts are unique to Cobra R. These are induction-hardened GKN units with the strength to perform reliably under the 5.4-liter engine’s higher torque loads. Shaft diameter is unchanged from the Cobra, but the inner splines have 31 teeth instead of 28, the inner tulips are a tripod design, and the right-side shaft is shorter to accommodate the larger differential.

Suspension and Steering
To complete the performance equation, the SVE team has engineered the Cobra R’s suspension to provide handling that matches its high power output. The Cobra R’s suspension follows the SVT tuning philosophy for road cars, compliant and subtle, but at a much higher level, with a strong emphasis on race-track handling.

The engineers optimized tuning to balance center-of-gravity height, aerodynamic downforce, ride height, overall grip on bumpy roads, along with driving fun and driving ease at the limit. The result is a car that achieves a remarkable lateral acceleration measurement over 1.0g on the 100-foot skidpad.

This compares with 0.89g for the ‘99 Cobra, and it also exceeds the numbers posted by Cobra R’s best-handling competitors. The 2000 Cobra R is equipped with Eibach coil springs, which lower the car 1.5 inches in front and 1.0 inches at the rear, and make a major contribution to its handling capabilities. The front spring rate is 800 lb./in., while the rear rate is 750 lb./in. This compares with 500 lb.Iin. front and 470 lb./in. rear on Cobra. These spring rates make the Cobra R 30 to 40 percent stiffer than the production ‘99 Cobra, and capable of canying a significant amount of aerodynamic downforce.

Bilstein shock absorbers with digressive valving provide the wheel control for Cobra R’s racing application. The front shocks are gas-charged monotube while the rears are gas- charged twin-tube. Testing proved that Cobra’s front and rear stabilizer bars provided the handling characteristics that the chassis engineers required for the Cobra R.

Compared with Cobra, all the Cobra R’s suspension control arm and rear subframe bushings are made of stiffer material, which improves handling by reducing compliance-steer under the higher cornering, acceleration and braking forces generated in racing. In addition, the Outer pivot of the upper control arm has been relocated to provide increased camber.

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