how to clamp a void operator properly

Hi, i have an object that has a z rotation that should be clamped to 45 degrees each side. The problem is that transorm.Rotate returns nothing and im a bit stuck how to clamp it properly. will appreciate any help.

Thanks in advance.

 #pragma strict
 
 public var speedModifier: float;
 public var speed : float  = 0;
 var arm : armScript;
 public var position : Vector3;
   
 
 function Update (){
 var armAngle: float = arm.angle;
 
 if (armAngle > 0.42){
    speed = -20;}
    else {speed = 20;};

 transform.Rotate(Vector3.back, speed * Time.deltaTime);
   
   GetComponent.<Rigidbody2D>().velocity.x = transform.rotation.z * speedModifier;
  
  transform.position =  new Vector3
  (
  Mathf.Clamp (transform.position.x, -2.2,2.2), 0.0f
  );
 
 }