Car Physics

Hello, i recently started new project, and have some problems with my car physics. I was searching the internet all day and found this script

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class BMW_i8 : MonoBehaviour
6. {
7.     private float m_horizontalInput;  // A & D
8.     private float m_verticalInput; // W & S
9.     private float m_steeringAngle; // Modified by m_horizontalInput
10.  
11.     public WheelCollider frontDriverW, frontPassengerW; //W = Wheel
12.     public WheelCollider rearDriverW, rearPassengerW;
13.     public Transform frontDriverT, frontPassengerT; //T = Transform
14.     public Transform rearDriverT, rearPassengerT;
15.  
16.     public float maxSteerAngle = 30; // 30 Degrees Max Steering Angle
17.     public float motorForce = 50; // Motor Torque Variable
18.  
19.     ////////////////////////////////////////////////////////////////////////////////////////////////////
20.  
21.     public void GetInput()
22.     {
23.         m_horizontalInput = Input.GetAxis("Horizontal"); //Unity Input Method (Edit > Project Settings > Input)
24.         m_verticalInput = Input.GetAxis("Vertical");
25.     }
26.     private void Steer()
27.     {
28.         m_steeringAngle = maxSteerAngle * m_horizontalInput;
29.         frontDriverW.steerAngle = m_steeringAngle;
30.         frontPassengerW.steerAngle = m_steeringAngle;
31.     }
32.     private void Accelerate()
33.     {
34.         frontDriverW.motorTorque = m_verticalInput * motorForce;
35.         frontPassengerW.motorTorque = m_verticalInput * motorForce;
36.  
37.     }
38.     private void UpdateWheelPoses()
39.     {
40.         UpdateWheelPose(frontDriverW, frontDriverT); // Taking Pose Information from _collider and Applying it to the _transform
41.         UpdateWheelPose(frontPassengerW, frontPassengerT);
42.         UpdateWheelPose(rearDriverW, rearDriverT);
43.         UpdateWheelPose(rearPassengerW, rearPassengerT);
44.     }
45.     private void UpdateWheelPose(WheelCollider _collider, Transform _transform)
46.     {
47.         Vector3 _pos = _transform.position;
48.         Quaternion _quat = _transform.rotation;
49.  
50.         _collider.GetWorldPose(out _pos, out _quat); // Out Values
51.  
52.         _transform.position = _pos;
53.         _transform.rotation = _quat;
54.     }
55.     private void FixedUpdate()
56.     {
57.         GetInput();
58.         Steer();
59.         Accelerate();
60.         UpdateWheelPoses();
61.     }
62. }
63.  

which i use in my game. Here's video from my problem:

I have some stutters while driving, and most important bug is that whatever float i set speed to be, it is approximately always the same, can't go faster. Any tips?

 

TL;DR: Increase your motorForce value to more than 50.

You are moving a Car that weights 1500 kilograms with a force of 100 newtons (50 on each rear wheel).
Thats an acceleration of (a = F/m) 0.066 m/s^2, which for what you want is probably very low.
Edit: Disregard, as @AlTheSlacker pointed out, I confused Torque and Force...

 

I see you tried different torque values and it made no difference (incidentally, @Erakk don't confuse torque and force). Have you looked to see how much slip you are getting from the driven wheels? You can get this from GetGroundHit -> WheelHit. I wonder if you are just spinning the wheels.

Have you tried to print() m_verticalInput * motorForce from the Accelerate() method to confirm you are reading the controller input correctly? I think the key press routines should be checked in the Update() method not the FixedUpdate()

I see you have wheel damping rate set to 1, which I find can be confusing, especially when trying to debug, although I don't think it will be your problem, you could try setting it to 0.0001 (minimum value).

 

I said, no matter which value i set it to, it is always the same