Question Trying to make realistic car axle

Hello,

I'm trying to make a car game/project kinda from scratch, without using wheel colliders. I want to add more details and realism so I thought I would start with a simple car axle that moves forward and backward by rotating the axle (which in turn will rotate the wheels, I've used 2 cylinders for the wheels and fixed them to the axle with fixed joints)

I already encountered some problems, when I accelerate the axis, it starts steering to the right a little, even though all component objects have the default rotation (y axis) on 0.

Also from my understanding if I apply rigidbody torque on the X axis, the axis should always rotate forward (or backward) to it's facing direction, but when the axle rotates on the y axis the force no longer spins the axle on the x axis. (This might be my fault for not understanding the addTorque function, but I'd appreciate some help)

TL;DR Axle with fixed joints as wheel starts steering left even though i only apply torque forward

All help and suggestions are welcome.

My Move script used on the axle :

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Move : MonoBehaviour
6. {  
7.     public Rigidbody rb;
8.     public float speed;
9.     private void Start()
10.     {
11.         rb = GetComponent<Rigidbody>();
12.         rb.maxAngularVelocity = 100000;
13.     }
14.     // Update is called once per frame
15.     void FixedUpdate()
16.     {
17.         Vector3 vector = new Vector3(1f, 0f, 0f);  
18.         if (Input.GetKey(KeyCode.W))
19.             rb.AddTorque(vector * speed * Time.deltaTime);
20.         else if (Input.GetKey(KeyCode.S))
21.             rb.AddTorque(vector * -speed * Time.deltaTime);
22.            
23.  
24.     }
25. }
26.