Boxing the Frame
Is Boxing the Frame Really Necessary?
I'm looking for your opinion on my current project, which will be a Willys flatfender Jeep. Specifically, I'd like your input on my approach to the frame. The chassis I'm building from is a '70 CJ-5 Renegade. The frame is straight and rust-free since it was a southern vehicle. It has a few minor stress cracks at weld joints, which I'm in the process of repairing. My approach to this project build is based on my intended use of the vehicle. I plan to drive it on the street a lot and in the dirt as often as possible. The trails I run are mostly mild to moderate, with the occasional trail approaching Rubicon levels of difficulty. I certainly won't be running the Hammers, and the Jeep won't be a hardcore rock crawler. Tire size will be limited to no more than 33 inches, and the engine is a rebuilt 231 V-6, not a modern V-8. Considering the equipment and intended use, I'm choosing to stick with the stock frame, without boxing or reinforcing it. Based on my research, boxing or reinforcing only part of the frame can actually invite cracking, as it interferes with the intended flex, causing stress points that weren't considered in the original design. Some folks scoff and tell me I have to box the frame, but to me it's an unnecessary addition of weight and money that can be applied elsewhere. And I remind the well-intentioned givers of advice that flatfender Jeeps were crossing the Rubicon regularly since before they were born. I'm eager to have you weigh in on this issue.
Richard, we're with you on this one. Tell the well-intentioned givers of advice to build their own rigs and invite them to do it any way they please. For the type of intended use you described, the stock frame with the repairs you've applied should be sufficient. In the event you do experience cracking, you can tackle this with additional repairs or simply by boxing particular trouble areas, which typically occur around the steering box and suspension mounting points. Keep in mind that we would likely box in or reinforce these areas if running 35-inch-or-larger tires and intended to hit extreme trails like the Hammers, but you should be fine if daily driving and the occasional difficult trail are all that the Jeep will tackle. If you do elect to add some reinforcement to the frame, check out Mountain Off-Road [(877) 533-7229, www.mountainoffroad.com], which offers frame-reinforcement kits for various model CJs. Thanks for writing. 'Wheel on.