I am trying to use the toy car reactor. My car is made up of a chassis and 4 wheels. I also have a ground plane which is just box.

I have added all the object to the rigid body collection
added the chassis to the chassis button on the toy car reactor
added the wheels

Set the angular speed to 5 and the gain to 2

In the reactor property editor I set the ground plane to unyieding.
Set the mass of the chassis and the wheel to 5 and friction to 3.

When I preview it. The 4 wheels appear in the preview. Then when I press P to play the preview the wheels disappear.

When I create an animation and then run the animation nothing happens

I have a attached a screen shot of the the reactor messages. The only thing I can see is the density is too high. I’m not sure how to change this.

3DS Max 2012
8gb Ram
quad Core

Reactor is a kind of physical simulation, therefore it is important to use correct scale when using it.
How are your system units and display units set? How big is the car in these units? Is the Reactor world scale and gravity set correctly to match these units?

The only thing I can see is the density is too high. I’m not sure how to change this.

Density = Mass / Volume
So to lower the density, either lower the mass or increase the volume.
The mass units used by reactor are Kilogams, so you have a chasis weighing 5Kg and four wheels weighing 5Kg each. Does this seem reasonable considering the size of the car in the units you have set? Generally you would expect the chasis to be heavier than the wheels. At that weight you are talking about a toy car not a real one, but not a matchbox car, more like the kind a child would sit in.
If it’s saying the density is high, you have the weight of a sit on car, but the size of a matchbox car.
Working with reactor, from the beginning think about the scale of your objects, is it a real life full size car, or an actual toy car. Then set your system and display units accordingly. Then model to a realisic scale. When assigning mass to objects, think about how much they would really weigh in Kg. In Reactor, set the world units according to your scene units, and set the gravity.

Samab. Thanks for your feedback. That makes reactor a lot clearer.

My units are set in metres and the car is a Audi. So basically my wheels are to heavy. I need to lower the mass of the wheels

3DS Max 2012
8gb Ram
quad Core