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This tutorial is to create the simple car rig you see in the video above using 3dsmax and Reactor physics simulation. I'll assume you don't know much about 3dsmax or Reactor, so should be able to follow it and get similar results to me. I'm going to provide all the values that I used so you can repeat exactly what I have, but feel free to experiment.

First, create a cylinder with radius 10 and height 1. Increase number of sides to 36 to make the motion a little smoother. Set the pivot point to be centred by going to the Hierarchy tab at the top of the right hand panel, then click "Affect Pivot Only", and "Centre to Object". This makes sure that the position of the wheels will be symmetrical on both sides when we come to add extra wheels. You can also make the height greater than 1 to make it a bit more sturdy, but 1 worked just fine for me in the video you see above.

Centre it to the origin by changing the space setting to 'World' (see below), and then right click on the slider of each axis of the object's position to set it to 0.



Rotate the cylinder 90 degrees along the y-axis, then move it 15 units in the x-direction and 20 units in the y-direction. It's easier to rotate if you turn on Angle Snap Toggle like I have in the image above (5th icon on the right of the 'world' selection). Then to move it exactly 10 units just type in 10 at the bottom, rather than moving it manually with the mouse. This value has to be exact to make sure the opposite wheels are also moved 10 units so the car is balanced.

Create a copy of the cylinder (shift and drag) in the y-direction and move it a sensible distance, as much as you like really. I moved mine 40 units, so it was balanced out with my y-position of the front wheel - so I set the y-value to -20.

Next make copies of both of these wheels by shift and dragging in the x-direction. Then set the world x-value to -15, to balance out the original wheels. You should now have something like this:



Now create a box. Mine has length 40, width 20 and height 10. The number of segments can remain at 1 for now. If you've done the above steps the same as me, you can right click on each positional axis of the box to reset it to the origin, and it will sit perfectly the middle of the wheels.

Create a simple plane and move it underneath the car so far to act as the ground.

Reactor time. If you haven't done so already, it's probably easiest to right click on the top toolbar and bring up the reactor toolbar. Select all objects in the scene, then select the first icon in this toolbar, which should be 3 boxes. This will add your objects into the simulation.

Select the wheels and open the Property Editor (4th icon from the end in the toolbar). Set the mass to 10. Select the box and set its mass to 25, and change the simulation geometry to bounding box. Select the ground plane and set it to unyielding and concave mesh.

If you preview the simulation now (2nd icon from end in toolbar), you should have all the objects in the scene, and everything falling to the ground when you press play. A cool thing you can do in the preview is right click an object and fling it around, but that's not very helpful just now.

You should have something like this uncoordinated car now:



To attach the wheels, add a Toy Car (12th icon from start of toolbar) into the scene by selecting it then clicking in the scene. On the panel that opens on the right, click the "none" next to Chassis and pick the box. Click the Add button underneath wheels and add the four cylinders.

To give the car some forward motion, tick the 'spin wheels' box.

Open up the preview again and you should now have a moving car. You can play around with the suspension to make it look a little more interesting - the lower the value, the softer it is. Edit the ground plane for some bumps and it will work them out and drive over them where physics will allow. I used a simple noise modifier on the plane on the video above, but you can edit however you like.



This is exactly what I used in this video. For my more advanced rigs I didn't use reactor, so they'll require a different tutorial at some point if there's any requests for it.

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