MINI COOPER Inverted strut coilover system

This inverted strut suspension by Intrax is just amazing. The Mini Cooper S (in this the John Works version) has a nice torque engine, a beautiful quality feel and has a great balanced suspension for daily driving. The car is safely understeered, making it a very sensible option.

For doing less sensible things however, the suspension falls short. At the corner entry the car does not want to move with its (too) planted rear, making turn-in and corner entry difficult and slow. Midcorner it keeps its under steer. As soon as the power is released the under steer worsens. The traction coming out of the corner is not as good as it could be from the grippy tires. The electronic differential needs to work overtime to make the best of the available mechanical grip.

The Intrax suspension transforms the car and gets rid of the standard understeer behavior. It improves the traction on the front by an amazing amount and gives the feel like there is a lock-up diff mounted. It can be ridden low (-60mm from Cooper S) and is still comfortable.  A few pictures are added, but really driving is believing.

The front is an inverted strut system.  The ideal Mc. Pherson strut is infinite stiff. It has zero friction going over bumps and when loaded (under cornering and braking). The Intrax 1K2 suspension comes already close to this ideal because of its inverted strut and the larger then standard diameter (40mm instead of 22mm). The Intrax inverted struts also use an unique floating bearing principle. Because of this, the further the shock is loaded and compressed, the larger the overlap between the bearings becomes. Therefore, when you need it the most , the strut is at its strongest.

The suspension has adjustable damping and adjustable ride height on the front and rear. 

Different from our competitors, Intrax chooses for one single adjuster knob for both the compression and rebound adjustment. With this single knob the total damping can be adjusted over a wide range of 40 clicks from “comfortable” to “sportive/hard”. By using one knob the relationship between compression and rebound always stays correct. Also different from most of our competition, our adjuster changed not only the rebound but also the even more important low-speed and high-speed compression damping. The RSA has an internal thermostat that keeps the damping constant, avoiding the harsh ride in the cold morning, and the loss of damping in the heat of the battle.


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