Adjustable Caster / Trailing Arms - 996/997/986/987

Technical

Caster Adjustment

Set the Ideal Caster for Better Lateral Grip

Caster angle is critical to a MacPherson strut front suspension because it increases the amount of camber that is gained as steering angle is increased. It also improves the centering torque on the steering wheel for straight line stability and additional tire feedback. The result is better grip mid-corner and an improvement to peak braking by slightly reducing the need for static camber.

Adjustable caster also allows you to adjust the wheel location (side view) to prevent tire rub with the front bumper, or fender in some cases.

If mounted in the rear, there is no caster angle benefit due to the lack of significant steering angle, however the length of the trailing arm is important for setting the bumpsteer and other kinematic behaviors of the rear suspension.

Track Width Adjustment

Get More from the Inner Tire

Extending the front track width promotes a more neutral handling behavior and reduces the overall amount of weight that shifts off the inner tire and onto the heavily loaded outer. This is a big reason why Porsche has added nearly 5" (124mm) to the front track of the 911 GT3 since the 996, and nearly 3" (72mm) to the Boxster/Cayman since the 986. The SPL front lower control arm, SPL tension / traction arm, and an adjustable camber plate allows you to properly maximize front track width and set your ideal camber angle.

Anti-Geometry Adjustment

Fine Tune the Chassis Response Under Hard Braking or Acceleration

INSTALLED IN THE FRONT

In the front, the provided spacers allow for fine tuning of the anti-dive geometry. The more anti-dive (expressed as a %) a car has less the front suspension will compress under braking. This geometry becomes more important as cars increase braking force with grippy tires and aero, especially on bumpy tracks and softer front spring rates. Changing anti-dive geometry can be helpful when setting up the front suspension to maintain acceptable front splitter heights or sufficient front suspension travel.

INSTALLED IN THE REAR

When mounted in the rear, the adjustment affects the anti-squat geometry, which is essentially the same concept as anti-dive. The more anti-squat (expressed as a %) a car has the less the rear suspension will squat under acceleration. This geometry's effect is more pronounced in lower gears and higher rates of acceleration. Additional anti-squat can prevent bumpsteer on corner exit and improve corner exit acceleration as well as peak tire grip available under hard acceleration. Certain road surfaces and setups may benefit from running slightly less anti-squat, so we've left it adjustable in small increments.

For big aero cars, adding anti-squat can also be a beneficial tool for keeping the rake angle of the chassis in the proper range on corner exit. The more the rear suspension compresses, the higher the front splitter rises, which can lead to a sudden reduction in front grip prematurely in the corner.

INSTALLED IN FRONT AND REAR

This kit can be installed in the front or the rear of the 996 and 997, or it can be paired with RTR 986 or RTR 981 for the rear of the Boxster and Cayman (986/987/981). This allows for fine tuning of both the above anti-geometries which also migrates the sideview instant centers (SVIC) and resulting pitch axis of the car. This has an affect on lesser anti-geometries such as front anti-lift (AWD - front axle accel) and rear anti-lift (AWD/RWD - braking) for those seeking a very specific chassis behavior on a setup. Note: Certain geoemetry changes may require modification of the spacer stack.