Stiffness and Gap in joints [2D]

I've been trying to make a folding joint in 2D physics system using hinge joints. The problem is I can't make the joints stiff and when the two connected objects move a bit far from each other, gaps start to appear.. for example.. when you make a ragdoll the joints are very close together and normally no gaps appears until you make the ragdoll move crazily.

So how can I fix this?