18". 20" Wheels. Edge. MKX; 17". A component (mounted in the center of the spring) which cushions the spring as it is compressed. Jounce Bumper. Auxiliary spring. Boot. Bushing. Coil Spring Damper. Control arm. Jounce. Knuckle. Shock. Spring seat. Suspension crossmember. Track bar. Trailing arm. Wedge.