has anyone have chasiss flex during the ride

iv got a problem when i go off into the trails and do crawling and going over ruts and roots and or rocks my frame has a little flex but has anyone came up with an idea on how to beef up the frame so this does not wind up bending

run angle iron on the inside of the fame rails

One of the moderators was building a custom chassis for his pan chassis machine - heres the thread link:
http://atltf.forumotion.com/t25-al-ko-mudding-tractor-build

I know mine does. Doesn't seem to harm anything for me. I've taken mine through the woods, over logs, trees, dirt piles, and holes and it still kept going. I did wonder what would happen to the belt, if the flex would make it slip off?

not a problem on my old mower, its got alot of weight on it aswell never had the chassis flex on me

yes, i used to but i figured out that some bolts needed to be secured better or added. that ended up being a fun romp. also once you lock up your trans axle you will put alot of stress on your frame. giving you frame flex, one way that you could stop all that is, welding up your frame solid and gusseting the frame where its needed.

It shouldnt really harm anything, but over time it could crack the pan chassis - even welding some angle inside the chassis would help.