I haven't experienced collision failures like this before. Which version of Blitz are you using? I remember that collisions were "tightened up" a while back. Not sure exactly what was different about them but it may help.
If the problem is as Madjack says then a simpler solution could be to move the pivots a very small amount away from the terrain mesh in the direction of the collision normals each frame.
Stevie
If the problem is as Madjack says then a simpler solution could be to move the pivots a very small amount away from the terrain mesh in the direction of the collision normals each frame.
Stevie