Car Question

Its something i've battle with a lot!

To begin with you have to really play around with the wheel collider settings to find the balance primarily on the driving sensation you want and also with the mass & scale of the vehicle.

in order to make the adjustments faster i had made a script where you can add all the wheels collider and adjust the setting with sliders. with a Debug toggle that will stop adjusting the setting on every frame. (ive put the code at End).

Now other tricks you can do to reduce flipping are:

• Reduce the center of mass in the rigidbody EX: myRigid.centerOfMass = new Vector3 (myRigid.centerOfMass.x, centerOfMass, myRigid.centerOfMass.z);

• Depending on the velocity of the car start applying some vertical force to the rigidbody that will push it to the ground EX:`myRigid.AddForce (new Vector3 (0, -pushDownForce, 0));`

• Lastly while researching this at a tutorials i have found a little JS script that basically works as an antiroll bar that was quite usefull. i dont remember who wrote it... i hope its ok that i am passing the code like that!-) Antiroll_Bar.js:

      var WheelL : WheelCollider;
       var WheelR : WheelCollider;
       var AntiRoll = 5000.0;
       
       function FixedUpdate ()
           {
           var hit : WheelHit;
           var travelL = 1.0;
           var travelR = 1.0;
       
           var groundedL = WheelL.GetGroundHit(hit);
           if (groundedL)
               travelL = (-WheelL.transform.InverseTransformPoint(hit.point).y - WheelL.radius) / WheelL.suspensionDistance;
       
           var groundedR = WheelR.GetGroundHit(hit);
           if (groundedR)
               travelR = (-WheelR.transform.InverseTransformPoint(hit.point).y - WheelR.radius) / WheelR.suspensionDistance;
       
           var antiRollForce = (travelL - travelR) * AntiRoll;
       
           if (groundedL)
               rigidbody.AddForceAtPosition(WheelL.transform.up * -antiRollForce,
                      WheelL.transform.position);    
           if (groundedR)
               rigidbody.AddForceAtPosition(WheelR.transform.up * antiRollForce,
                      WheelR.transform.position);    
           }
   
  
  

Here the code for the WhellCollider settings :

 using UnityEngine;
 using System.Collections;
 [System.Serializable]
 public class WheelSettingCS : MonoBehaviour
 {
 
         public WheelCollider[] wheelColliders;
 
         public bool debugMode = false;
 
         [Range(0 , 10)]
         public float
                 mass = 1;
 
         [Range(0 , 2)]
         public float
                 distance = 0.2f;
 
         [Range(0 , 10000)]
         public float
                 spingVal = 5500f;
 
         [Range(0 , 100)]
         public float
                 spingDamper = 50f;
 
         [Range(-100 , 100)]
         public float
                 position = 0;
 
         [Range(0 , 5)]
         public float
                 ffextremumSlip = 1;
 
         [Range(0 , 40000)]
         public float
                 ffextremumValue = 20000;
 
         [Range(0 , 4)]
         public float
                 ffeasymptoteSlip = 2;
 
         [Range(0 , 20000)]
         public float
                 ffasymptoteValue = 10000;
 
         [Range(0 , 1)]
         public float
                 ffstiffness = 0.092f;
 
         [Range(0 , 5)]
         public float
                 sfextremumSlip = 1;
 
         [Range(0 , 40000)]
         public float
                 sfextremumValue = 20000;
 
         [Range(0 , 4)]
         public float
                 sfeasymptoteSlip = 2;
 
         [Range(0 , 20000)]
         public float
                 sfasymptoteValue = 10000;
 
         [Range(0 , 1)]
         public float
                 sfstiffness = 0.092f; 
 
 
         // Use this for initialization
         void OnEnable ()
         {
                 FixSpringSettings ();
         }
     
         // Update is called once per frame
         void FixedUpdate ()
         {
                 if (debugMode)
                         FixSpringSettings ();
         }
 
 
         void FixSpringSettings ()
         {
                 for (int i = 0; i < wheelColliders.Length; i++) {
             
                         WheelCollider whellCol = wheelColliders [i];
                         whellCol.suspensionDistance = distance;
                         whellCol.mass = mass;
 
                         JointSpring newSuspesion = new JointSpring ();
                         newSuspesion.spring = spingVal;
                         newSuspesion.damper = spingDamper;
                         newSuspesion.targetPosition = position; 
                         whellCol.suspensionSpring = newSuspesion;
 
                         WheelFrictionCurve newFwdFriction = new WheelFrictionCurve ();
                         newFwdFriction.extremumSlip = ffextremumSlip;
                         newFwdFriction.extremumValue = ffextremumValue;
                         newFwdFriction.asymptoteSlip = ffeasymptoteSlip;
                         newFwdFriction.asymptoteValue = ffasymptoteValue;
                         newFwdFriction.stiffness = ffstiffness;
                         whellCol.forwardFriction = newFwdFriction;
                                             
                         WheelFrictionCurve newSideFriction = new WheelFrictionCurve ();
                         newSideFriction.extremumSlip = sfextremumSlip;
                         newSideFriction.extremumValue = sfextremumValue;
                         newSideFriction.asymptoteSlip = sfeasymptoteSlip;
                         newSideFriction.asymptoteValue = sfasymptoteValue;
                         newSideFriction.stiffness = sfstiffness;
                         whellCol.sidewaysFriction = newSideFriction;
 
             
                 }
 
         }
 
 }