AST 4200 Damper Sets/Suspension Packages

Race-derived, high pressure monotube coilover suspension engineered specifically for serious driving school and race level performance.

The AST 4200 damper set is a premium, double (separate rebound and compression) adjustable system designed and engineered to be a high value in the world of race level, double adjustable damper sets. These coilover-type damper sets are handmade in Holland from high-tolerance components typically found on race-specific suspensions. The AST 4200 system is designed specifically for serious driving school performance and race level use. This means elevated durability and longevity, simple adjustability, and the ability to control stiff spring rates. The 4200 system use AST’s Twin Piston Dual Adjust (TPDA) technology. Similar non adjustable versions have been found in the highest forms of racing. TPDA builds on this technology to allow for two adjustment knobs to be mounted on the shock body (no tools required). Quick rebound and compression changes can be made in the pits in seconds. The 4200 uses internal nitrogen reservoirs to comply with race classes that do not allow "remote reservoirs".

AST dampers are monotube design for a reason - they perform better. You can notice the benefits in mid-corner bumps and fast transitions where true premium shock performance becomes evident. Other damper designs (typically "twin tube" or a low pressure monotube) on the market exist for two reasons: comfort and cheaper manufacturing processes. AST's monotube design translates into a bigger piston to control higher loads and extended driving stints. This translates directly into the ability to fine tune the shock and have consistent damping responses (no guess work). Other shocks using a twin-tube design have much smaller pistons lessening their ability to handle performance loads reducing the flexibility for adjustments. AST dampers are pressurized with nitrogen to a minimum of 175psi which keeps the oil from cavitating around the piston, making the shock less effective. Pressurizing the oil makes a consistent environment for the valving and oil to do its job correctly with every stroke.

AST dampers use a dual, shim stack/bypass valve design for added durability, extended service intervals, and consistent tunability. Longevity between rebuilds* is relatively long, especially considering the fine tolerance levels of these dampers. Dampers are specifically valved in the range of medium to relatively high spring rates for street/track use. Custom valving is available to suite particular chassis setups where high spring rates are necessary - Please give us a call concerning this option.

Key Features:

• Monotube design offers larger valving for optimal performance and durability
• Purpose built strut and shock bodies, shortened from stock lengths
• Floating piston design with high pressure nitrogen (>175psi) means no cavitation around the piston (consistent performance)
• Anodized adjuster knobs permanently mount on the damper and feature firm click indentations
• 12 point rebound and compression (separate) settings allow straightforward tunability
• Rear adjustable perches included for height adjustability/corner balancing
• Fully threaded strut bodies allow maximum tire width below perch assembly
• Large, 22mm diameter strut shafts incorporate a double piston assembly for added durability
• Aluminum cylinder body shocks
• Rear shocks use spherical lower mounts (4100 series use rubber) for optimal performance
• Adjustment hardware included

Strut Mount Options:

• Ground Control Race Camber/Caster Plates - Spherical bearing type mounting plate offers camber and caster adjustability
• Ground Control Hybrid Camber/Caster Plates - Utilizes a rubber isolator for reduced NVH (Noise, Vibration, Harshness) - Great for street cars. Requires a 2.5" ID spring (perch adapters included)
• Ground Control Street Camber/Caster Plates (E46 M3 Only) - Great street/track mount designed specifically for the E46 M3. Stock like NVH and longevity. Requires a 2.5" ID spring (perch adapters included)

Shock Mount Options:

• Ground Control Spherical - Billet alloy/spherical bearing rear shock mount incorporating a shock tower reinforcement bracket - Suggested for track use only
• Ground Control Urethane - Billet alloy/urethane rear shock mount incorporating a shock tower reinforcement bracket

Spring Options:

• By inserting a numerical value in the spring rate write-in box we will include (4) springs with a price of $300 for the set (By not adding a value to the write-in box, springs will not be added to the order)
• Springs are made by Hyperco and available in numerous rates (Please contact us with help concerning spring ordering. We will help select the best spring rates to suite your driving needs and spring length based on the requested ride height.)

E30 customers will need to ship their strut housings to Holland for custom modification to allow fitment of 4200 strut and coilover perch.  Please contact your sales person for assistance.

E8X/E9X applications require use of the E9X M3 rear lower control arm for an eye-mount design.

*AST offers quick rebuilding and revalving services here in the USA (starting at $125 per damper)

One year/unlimited mile warranty - Made in Holland