2D car brakes help???

hello im having trouble with my brake system when i press space and S the car flys off and it only works forward but not backwards this is really made me mad and cant find the answer :expressionless:

heres the code

using UnityEngine;
using System.Collections;

public class NewBehaviourScript : MonoBehaviour {

	public float speedF = 10f;
	public float speedB = 10f;
	public float mph;
	public Vector2 hat;
	public float throttle;
	public float moderation = 0.5f;
	public float decrease = 0.3f;
	public bool braked = false;
	public bool brakeS = false;
	public GameObject wheelB;
	public GameObject wheelF;
	private Vector2 speed = new Vector2(3, 0);
	
	void Start()
	{


	}
	void OnGUI(){
		
		mph = rigidbody2D.velocity.magnitude * 1;
		
		Debug.Log("Mph: " + mph);

	}
	void FixedUpdate()
	{
		handBrake ();
	}
	void Update () {


			throttle +=Input.GetAxis("Vertical")* 50;
			throttle -= decrease;
			throttle  = Mathf.Clamp(throttle,0,25);
			print (throttle);
			
		 
		if(Input.GetKey(KeyCode.W))
		{

			wheelB.rigidbody2D.AddTorque(throttle);


		}
		if(Input.GetKey(KeyCode.S))
		{
			wheelB.rigidbody2D.AddTorque(-speedB);

		}
	
	}
	void handBrake()
	{
		if(Input.GetButton("Jump"))
		{
			braked = true;
		}
		else
		{
			braked = false;
		}
		if(braked)
		{
				//wheelB.transform.rotation = Quaternion.identity;
				//wheelB.rigidbody2D.AddTorque(-mph * 10);
		
			wheelB.rigidbody2D.AddTorque(-mph * 10);

		}
		
		
	}
}

i fixed it with fixedangle