GTM Spyder Suspension

SPYDER OVERVIEW          SPYDER SPECS          SPYDER SUSPENSION

The GTM Spyder has a conventional double wishbone suspension at the front and double trailing arm suspension at the rear. The mid-engined layout gives a near-perfect weight distribution of 45% front / 55% rear and its low polar moment of inertia makes it inherently nimble. The suspension has been tuned to inspire driver confidence with a consistent handling, communicative car.

Front Suspension

The front double wishbone suspension has long and wide based wishbones. Long wishbones give small camber change, good track control and less roll centre movement. Wide based wishbones minimise toe and castor change by reducing the shock and braking loads on the inner bushes. This reduces unwanted deflection and movement of the outer joints, giving better stability and a more consistent steering feel.

Anti-dive suspension geometry imposes castor change with suspension movement, so the front suspension has very little anti-dive. This is enough to allow the wheel to move back slightly under a bump condition, reducing the shock transmitted into the car and improving the ride.

The steering is unassisted rack and pinion with 3.7 turns lock to lock. To make the steering communicative without too much kickback, the scrub radius (ground offset) is 11mm positive. Self-centring is provided by 7 degrees of castor angle, and bump steer is virtually non-existent with near-perfect suspension geometry.

Rear Suspension

The rear double trailing arm suspension concept is similar to a double wishbone suspension turned around 90 degrees. This allows the chassis to be shortened to reduce weight, give better torsional stiffness and improve packaging around the engine. This layout also has a few advantages over conventional double wishbones with linear chamber change, zero track change throughout suspension travel, and a fixed roll centre at ground level.