I need help making wheels.

Questions & Answers
1

I have a 2d bike using wheel joints but using motors doesnt give me a smooth ride. I need it to accelerate on press and be neutral on release and only slow down by gravity and such. Can anyone help? My current code decelerates and brakes terribly.

using UnityEngine; 
using System.Collections; 
 
 
public class WheelCarJointMovement : MonoBehaviour { 
 //reference to the wheel joints
 WheelJoint2D[] wheelJoints; 
 //center of mass of the car
 public Transform centerOfMass;
 //reference tot he motor joint
 JointMotor2D motorBack;  
 //horizontal movement keyboard input
 float dir = 0f; 
 //input for rotation of the car
 float torqueDir = 0f;
 //max fwd speed which the car can move at
 float maxFwdSpeed = -5000;
 //max bwd speed
 float maxBwdSpeed = 2000f;
 //the rate at which the car accelerates
 float accelerationRate = 500;
 //the rate at which car decelerates
 float decelerationRate = -100;
 //how soon the car stops on braking
 float brakeSpeed = 2500f;
 //acceleration due to gravity
 float gravity = 9.81f;
 //reference to the wheels
 public Transform rearWheel;
 public Transform frontWheel;
 
 // Use this for initialization 
 void Start () { 
  //set the center of mass of the car
  rigidbody2D.centerOfMass = centerOfMass.transform.localPosition;
  //get the wheeljoint components
  wheelJoints = gameObject.GetComponents<WheelJoint2D>(); 
  //get the reference to the motor of rear wheels joint
  motorBack = wheelJoints[0].motor; 
 }  
  
 //all physics based assignment done here
 void FixedUpdate(){
  //add ability to rotate the car around its axis
  torqueDir = Input.GetAxis("Horizontal"); 
  if(torqueDir!=0){ 
   rigidbody2D.AddTorque(3*Mathf.PI*torqueDir, ForceMode2D.Force);
  } 
  else{
   rigidbody2D.AddTorque(0);
  }

  //horizontal movement input. same as torqueDir. Could have avoided it, but decided to 
  //use it since some of you might want to use the Vertical axis for the torqueDir
  dir = Input.GetAxis("Horizontal"); 
 
  //explained in the post in detail
  //check if there is any input from the user
  if(dir!=0)
   //add speed accordingly
   motorBack.motorSpeed = Mathf.Clamp(motorBack.motorSpeed -(dir*accelerationRate - gravity*Mathf.Sin((Mathf.PI)/180)*80 )*Time.deltaTime, maxFwdSpeed, maxBwdSpeed);
  //if no input and car is moving forward or no input and car is stagnant and is on an inclined plane with negative slope
  if((dir==0 && motorBack.motorSpeed < 0 ) ||(dir==0 && motorBack.motorSpeed==0)){
   //decelerate the car while adding the speed if the car is on an inclined plane
   motorBack.motorSpeed = Mathf.Clamp(motorBack.motorSpeed - (decelerationRate - gravity*Mathf.Sin((Mathf.PI)/180)*80)*Time.deltaTime, maxFwdSpeed, 0);
  }
  //if no input and car is moving backward or no input and car is stagnant and is on an inclined plane with positive slope
  else if((dir==0 && motorBack.motorSpeed > 0 )||(dir==0 && motorBack.motorSpeed==0)){
   //decelerate the car while adding the speed if the car is on an inclined plane
   motorBack.motorSpeed = Mathf.Clamp(motorBack.motorSpeed -(-decelerationRate - gravity*Mathf.Sin((Mathf.PI)/180)*80)*Time.deltaTime, 0, maxBwdSpeed);
  }
   
   
   
  //apply brakes to the car
  if (Input.GetKey(KeyCode.Space) && motorBack.motorSpeed > 0){
   motorBack.motorSpeed = Mathf.Clamp(motorBack.motorSpeed - brakeSpeed*Time.deltaTime, 0, maxBwdSpeed); 
  }
  else if(Input.GetKey(KeyCode.Space) && motorBack.motorSpeed < 0){ 
   motorBack.motorSpeed = Mathf.Clamp(motorBack.motorSpeed + brakeSpeed*Time.deltaTime, maxFwdSpeed, 0);
  }
  //connect the motor to the joint
  wheelJoints[0].motor = motorBack; 
 
 }
 
}
2

You must multiple​ “slope” variable with others in all sine functions.
Like this:

motorBack.motorSpeed = Mathf.Clamp(motorBack.motorSpeed -(-decelerationRate - gravity*Mathf.Sin((slope * Mathf.PI)/180)*80)*Time.deltaTime, 0, maxBwdSpeed);