TwistedPhil
+1y
The older Slam Bags did have a limited lifespan from UV deterioration, but if they weren't cracking before you installed them then there may be another reason for the failure.
Your subject title mentioned over arcing- what's the angle of your top vs. your bottom plate? Most bags have a maximum of 35 degrees (with limiting straps), so if you were over that or at that without any limiting straps or shocks, that could have been the final straw.
Let us know more about your setup (pics are great!) and we can help you out.
-Phil at FBI