The 4200 Series shocks 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 2 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. 4200s are fully customizable and rebuildable.
Proven on the street and track, this system is unmatched by any other system on the market. HP Autowerk's unique AST dampers matched with our custom Swift springs offers superb street manners and unmatched cornering capabilities for the track. Offering separate external compression(Double Adjustable Only) and rebound adjusters, the dampers can be tuned from street comfort to a full race setup in a matter of minutes.
Not looking for that slammed look? Or just want to retain stock ride hight, but want better handling? We can customize the spring rate and height for you! All other off the shelf coilovers can't do that for you!
We use the highest quality motorsport springs sourced from Swift. Why Swift?
Swift's R & D team created material, called H5S.TW, which is stronger then regular silicon chrome material. Because of this material, we could make the spring wire thinner, and could wind the springs with fewer coils, which greatly decreased weight while dramatically increasing available stroke.
We also use thrust sheets where possible. Here is why:
Thrust sheets provide a variety of benefits to coilover systems. As a spring becomes compressed the coils attempt to distribute the energy by unwinding. This is called twisted force. The unwinding makes the spring rate irregular. By allowing the spring to smoothly rotate around the perch during compression, the spring rate will return to normal. Thrust sheets also help dampening and rebound of struts too. Thrust sheet?s bearing action allowing the rotation of a spring allow the load on the spring to be more evenly Distributed which reduces lateral shock shaft load. Increased lateral load on shock shafts cause a reduction in the struts ability to rely on valves for dampening force.
Monotube design - gives the biggest piston sizes available
Floating piston design with high pressure nitrogen means no cavitation around the piston
Compression and Rebound adjuster knobs permanently mounted on the dampers – no fumbling for knobs
Fully threaded strut bodies allow maximum tire width without fender rolling or larger spacers
Rebuildable by AST-USA – get the valving you want, when you want it.
*Coilover shown with optional helper/tender springs and BMW radial bearings. Please call for specific applications
*Camber plates are required for the 1M and M3
*We stock all popular rates of high quality Swift springs
*Optional AST 5000 series dampers with remote reservoirs are also available
Applications for E36 and E46(including M3), E82, E90, E92, and E93.
Above is what the 4200 is all about. However, these were recently(May, 2012) fully rebuilt/revalved and new 4250 Double Digressive Pistons installed:
DDP Technology Piston
Our latest digressive piston developed for GRAND-AM gives drivers and race engineers the best of both worlds. Drivers love the low speed damping response and body control, while race engineers love the “blow off” at high shaft velocities. When the rebound adjustment is soft, the damper curve looks similar to an OEM street shock profile. When the rebound adjustment is hard, the damper curve looks like a race shock!
This “Jekyll and Hyde” personality is exactly what AST 4000 Series customers want: soft street ride and race car track performance in ONE shock - all with the turn of a knob!
Lower Drag Seals
High performance seals are a challenge for any damper. They must balance friction and sealing ability while not impacting shock performance and not leaking; a difficult balancing act! While the seal was originally developed for GRAND-AM road racing, AST is taking our knowledge from the track to the street again. Newly redesigned seals decrease hysteresis in the damper and decrease seal drag over 50%.
This particular kit was installed on my personal 1M and since I will be testing the new Vorshlag camber plates and Swift sport springs in the very near future so this kit will be removed from the vehicle.
Current spring rates are 400F and 672R(I can substitute other spring rates of your choice as well).
Retail on the AST 4200 is $3717 and the upgrade to 4250 is $1000+
You will also get the rear quick change spring kit(normally an additional $165) as part of the sale. Rear AST remote adjusters(a $70 value) will also be FREE.
Selling this kit with less than 5000 miles total and about 750 miles since the rebuilt/revalved for SOLD! shipped to the US 48 States.
***photo is the kit before installation***