car suspension and torque help

hi i have a 2d car with 2 wheels and its very cartoony so it has 2 large bars connecting the wheels to the rigidbody, to act as sort of suspension arms.. i need these to rotate slightly around the world z axis at the connection to the rigidbody when the wheels go over bumps, to simulate suspension, what can i do?

also i used a piece of script found in another answer to make the bounce on the wheels work, but now my motorTorque isnt working on the wheels, ive obviously gone wrong but i cant figure it out, any help would be great.

my script is as follows:

var lWheelCol : WheelCollider; var rWheelCol : WheelCollider;

var lWheel : Transform; var rWheel : Transform;

function Start() { rigidbody.centerOfMass = Vector3(0, -2.5, 0); }

function Update() {

lWheel.Rotate(Vector3.up, lWheelCol.rpm 6 Time.deltaTime); rWheel.Rotate(Vector3.up, rWheelCol.rpm 6 Time.deltaTime);

transform.LookAt(lWheel, transform.parent.transform.up);

transform.LookAt(rWheel, transform.parent.transform.up);

}

function FixedUpdate() { lWheelCol.motorTorque = 70 Time.deltaTime; rWheelCol.motorTorque = 70 Time.deltaTime; }

//function clamp (motorTorque : float, min :float, max : float) { //if (motorTorque < min) //motorTorque = min; //if (motorTorque > max) //motorTorque = max; //}

i understand its a tall order but any help would be great :)