Vehicle gets unstable when other actors are in contact (PhysX 2.8.1)


I have a Vehicle (a lorry truck). The physics model itself work fine, it behaves like I want it to. But as soon as I put a load on the truck bed (an actor) the truck behaves like it is lighter. You can even see the suspension goes up, just as the actor I put upon the truck as negative mass. The more actors I put on the truck bed, the less stable is the vehicle and its suspension. I would understand the problem if I had 1000 actors, but this problem arises with only one actor placed upon the truck.

I have tried different mass ranges and simulation step size but with the same or similar results. I have also tried disabling the NX_ADAPTIVE_FORCE

What would cause this strange behaviour?

Using PhysX 2.8.1