The cabin jumps out of frame

My 171 is a 2013 model. I bought it 7 months ago. I don't know how to describe this issue but here goes. As I drove it on a trip the two up front sides jumped out of the exterior one inch framing. So I removed that one inch right angle framing and replaced it front to back on both sides with two inch steel right angle framing. I thought I solved the problem but it did not. It seems the cabin jumps up while I am driving (or going over bumps) and  moves out of the side 2 inch framing. Consequently the door is no longer aligned and I have to push the front of the cabin back into position.  Can someone please help me find the solution to this problem.  Thanks.  Lonetraveler