Project Infiniti G35 Sedan: The Poor Man’s M3


Project Infiniti G35 Sedan: The Poor Man's M3
KW Suspensions G35 VIII kit is awesome!  Rust free stainless steel bodies and springs that fit the upper spring perches.  The rear spring has adjustable ride height via the adjustable lower seat.  The KW’s have some of the best ride quality to control of any suspension available.

Next we turned our attention to the suspension.  There are not many G35 sedan specific suspension mods on the market but we will be working with some of our site sponsors to come up with some new stuff for the G35.  The first and most critical parts of any suspension build are the dampers and springs.  We chose KW Suspensions Variant III coilovers because we feel that they are one of the best street suspensions out there for the serious driver.  They are also one of the best riding high performance street suspensions. Variant III’s are a unique advanced gas charged double damping adjustable twin tube damper. 

Although some people may dismiss twin tubes as low end dampers compared to monotubes, the KW’s are a high precision twin tube with the characteristics of a monotube.  The KW Variant III feature independent adjustability of compression and rebound damping which is a huge advantage over other higher end streetable suspensions on the market which are typically only single adjustable for global damping stiffness. Independent adjustability of compression and rebound damping is important for any car that is going to be tuned for optimal handling under a wide range of set ups and conditions like a daily driver that see’s some track use.

The VIII’s rebound adjustment primarily affects the low speed damping–shock piston velocities in the 0-2″ per second range.  Low speed damping adjustment affects body motions such as roll and pitch.  This is in the area which the driver feels the most when driving fast.  The V3 has the main shaft and piston riding in the inner tube of the shock body with the rebound damping adjuster built into the low speed circuit.  A threaded tapered rod that goes to an adjusting screw at the top of the shaft controls the size of the low speed damping orifice.  The knob is adjusted with an allen wrench. Screwing it in and out raises and lowers the tapered end of the rod into the orifice which changes the amount of fluid that can flow through it.  When the orifice is mostly blocked by the taper, little oil can flow and there is a lot of low speed damping. When the orifice is open, the fluid can flow freely and the damping is decreased.  The piston also has a unique two stage system combining a deflected disc valve system and a spring loaded blow off valve for controlling the rest of the velocity range.  This valve is one of the secrets for the KW’s smooth ride with good control.

KW Variant III rebound fluid flow
The low speed rebound damping is controlled mostly by fluid flow through the piston on the end of the shock rod.  Turning the rebound adjusting knob located on the top of the shaft screws the tapered metering rod up and down varying the size of the orifice.  The low speed fluid flow is represented by the green arrows.  At higher shaft speeds the mid and high speed circuit kicks in, the high speed fluid flow is shown by the blue arrows. The hydraulic pressure deflects the metering disc shown in yellow for mid speed damping and higher velocities allow the spring loaded blow off of the disc to open.

The compression damping adjustment is controlled by the foot valve. The foot valve lives on the bottom of the inner tube and regulates the flow of fluid between the inner and outer tubes. A spring loaded needle valve controls the size of the low speed compression damping orifice located in the foot valve as well as the valve spring preload.  The needle valve is adjusted via a thumb knob on the bottom of the shock body.  Like the rebound, the compression adjuster also mostly influences low speed compression damping, which like rebound is the part of the damping curve that influences body motion.  On rebound the fluid flows through orifices and the damping force is controlled by the unique combination of deflected dics valves with a spring loaded blowoff function. The combination of deflected disc valving and spring loaded blow off give KW’s their unique range of control with frequency sensitivity.  This helps the shocks produce both firm control and a smooth non tire shocking ride.

KW variant 3 foot valve fluid flow
In rebound, the shock’s foot valve located on the bottom of the shock, simply acts like a one way check valve allowing fluid displaced by the shock shaft to flow into the outer tube and the hydraulic accumulator.  The compression adjuster increases the spring preload on the compression blow off valve which is the yellow needle valve shown here.


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