Dragging Rigidbodies goes through colliders

I have a scene setup like an abacus

1 cylinder oriented horizontally. 3 rings, each made of one mesh and 4 capsule colLiders nested using empty game objects.

Each ring is draggable using the DragRigidbody script and things work well for the most part.

If i drag a rapidly drag a ring in a perpendicular direction it will break away from the cylinder.

I tweaked the physics settings, the size of the colLiders and still run into this issue.Has anyone tackled a similar collision problem?

UPDATE:

I also gave the following DragObject script a try from http://www.unifycommunity.com/wiki/index.php?title=DragObject No luck

If the objects are just going to stay on the cylinder like an abacus, you might want to try using a configurable joint. Will allow them full physics motion, but you can limit their movement in a certain axis.

Not sure how well this would work for that particular situation, but you can give this a try: http://www.unifycommunity.com/wiki/index.php?title=DragObject

I made the following adjustments. The rings no longer breakaway.

Set the Fixed timestamp to 0.005. IReduced the Solver Iteration Count to 3. Drastically reduced the tri count on the mesh colliders.