Ihave same issue with 2 SUMO trucks. Steering Knuckle is a weak spot. They have aluminum knucles at 69.99a pair or you can make your own if you have some soldering skils and brass tubing (can get this in any hobby store)
Please check my post with pictures here :
http://www.rcuniverse.com/forum/m_10834762/tm.htm
Jack