2015-2021 Subaru WRX STI Hipermax S Coilovers by HKS
After 9 years after the launch of MAXIV GT, the new HIPERMAX S series was born for superior “Driving Comfort" with advanced features in damping force, durability, and appearance. The new HIPERMAX S series continues to employ the single-tube structure. The advantage of this structure is to be able to provide the gas and oil chamber separately, and then it allows to use of a large diameter piston. As a result, a quality and stable damping force is gained. The Pre-load Valve System, introduced in the previous MAX IV GT 20 Spec, S-Style L, and S-Style C, created a remarkable difference in handling performance. This has been further refined to introduce “Dual PVS”.
High-speed damping is reduced while keeping unnecessary movement to a minimum. The improved shape of the needle expands the oil relief channel. Each step of the 30-step adjustment is now more prominent. Having softer adjustment options gives more options for street driving. For HIPERMAX S, a further improved “ADVANCED BUMP RUBBER” was developed which pursues further softness and also shorter variations delivering a wide range of options for a variety of cars delivering a natural and smooth experience. HKS previously introduced SNOW EDITION versions to combat corrosion head-on. The result of this development was PNE coating delivering 5x better durability compared to standard galvanizing.
Dual PVS. We evolved the existing preload valve system to the dual preload valve system to suppress the generation of unnecessary damping force during higher piston speeds. This provides major improvement in ride comfort without influencing the driving performance.
Wide Range Damping Force Adjustment Mechanism. The improved shape of the Needle Jet expand the range of damping force adjustment. This makes us possible to handle driving on a wider range of stages.
Evolution of Bump Stop Rubber. A new shape of bump stop rubber reduces the body roll and achieves ride comfort at the same time which cannot be achieved with general hydro bump stop rubber.
Low Friction Technology. With advanced tribology technology, we have achieved even higher durability and lower friction than conventional products. This technology contributes to improved ride quality and handling performance.
30 Levels Adjustable Damping
Shock-Body Length Adjustable
Dual Pre-Load Valve System
Rubber Upper Mount
Spring Rate [N/mm(kgf/mm)]: F=88(9.0) | R=69(7.0)
Spring Length (mm): F=220 (Straight Barrel Type) | R=170 (Straight)
Height at Factory (Upper-Lower): F=-19(0 to -41) | R=-14(0 to -59)
Upper Mount: F=Rubber | R=Rubber
Spring Rate Change at Factory [Changeable Spring Rate N/mm(kgf/mm)]: F=Possible [±10 (1)] | R=Possible [±10 (1)]