# Wheel Colliders and Rope Bridges

I have a somewhat odd physics problem involving wheel colliders. At this point I don’t know whether or not I can keep using the built in physics objects or roll my own controller but I have a relatively stable ‘dune buggy’ that is locked on a plane in its motion using rigid body constraints.

I made a ‘suspension’ bridge made out of a bunch of linked boxes connected via character joints. There is a lot of sag in the bridge but I can adjust that through mass settings, from an orthographic view the combined colliders create a smooth curve surface. When the dune buggy lands on the bridge from the air I suspect a ‘rubber band’ like effect which does occur. But what happens is that the rigidbody picks up incredible speed from the wheel colliders. When the car is set to 0 motor torque, and 0 brake torque on a non jointed hill with the same shape, the dune buggy just rolls into the valley. I expect the same from the bridge but it gets ‘launched’ as if it has some kind of speed boost.

So, any hints or suggestions on making a rope based bridge compatible with wheel colliders as if the bridge were normal terrain ?

I have another update, still having the same issue. It seems whenever the object underneath the wheel colliders has rotation or velocity this is occuring. I tried to boil down to a much simpler case, so now I have a sphere with locked rotation except in 1 axis and a constrained position, essentially acting as a ‘rolling pin’ Whenever my car lands on this sphere it bounces with incredible velocity in 1 tick…

Even more interesting is that the mass of the rolling pin has no effect 0.0001 and 10000 mass still causes the first collision to give the car near infinite velocity, and the rolling pin spins and ridiculous rates on collision

Man, it would be nice to use wheel colliders with other physics constructs, like a rocking bridge, or rolling pins.

Don’t know if this will help, I had a problem with physics and parts of my object were ejected to the space after about 5-10 sec of applying gravity. Then I realized I have a rigid body on empty object it was parented to. After removing rigid body component from parent, it works just fine