public void setRestLength(float restLength) {
        this.restLength = restLength;
        applyInfo();
    }
The maximum suspension force, raise this above the default 6000 if your suspension cannot
handle the weight of your vehicle.

@param maxSuspensionForce the desired maximum force per wheel
(default=6000)
jme3-jbullet/src/main/java/com/jme3/bullet/objects/VehicleWheel.java