Simplest possible car not working

Unity Engine
1

Hi everyone,

I have been working on a car game project for a while now. Its a gta 1 style car game and right now im only using a boxcollider with a rigidbody and 4 wheelcolliders. Im adding torque to the both back wheels to move it forward, but even with the both front wheelcolliders’ straight (steerAngle=0f) the car turns subtly to the right.

What could cause this?

I have found 4 posts on the forum regarding the same issue, but none of them got any good answers… So i guess im not the only one that could use some help.

I hope that someone that has experience from this can help me :slight_smile:

Here’s the four posts:
http://forum.unity3d.com/viewtopic.php?t=34891&highlight=car+automobile+problem
http://forum.unity3d.com/viewtopic.php?t=31264&highlight=car+automobile+problem
http://forum.unity3d.com/viewtopic.php?t=23774&highlight=car+problem
http://forum.unity3d.com/viewtopic.php?t=11914&highlight=car+problem

2

I’ve encountered this problem myself in the past - I don’t know why it happens, but I’ll run this past the development team to see if they have any idea.

3

Is you car mesh or whatever is being used to calc the inertia tensor for the rigid body symetrical down the centre line. I had this issue on one of my cars turned out to be the artist at added a small vent to one side of the car so when I set the centre of the mesh in max assuming it would be the exact mid point between the wheels it was actually slighyly offset to one side so the when I added the wheel colliders ± the same distance from the centre of the mesh they wernt actually equal distance from the cg for the rigidbody so I was getting a slight resulting turning moment from the tyres.