Nuts, I'm Confused
Body Flex
Q I purchased a '97 Jeep Grand Cherokee so I could go wheeling with my friends and bring my family along. Everywhere I went, everybody gave me the same response: "Ooh, how's the body flex on that?" I always gave the same answer: "Not bad at all."
I had never experienced or even considered this problem until I pushed my limits on some terrain I probably shouldn't have been on in a stock vehicle in the first place. I was wondering if you could explain what body flex is, how it happens, and how to prevent it. I knew I had it coming to me when I bought a unibody anyway; my friends will never let me live it down that I bought a "fake" Jeep. But it was practical for me!
Nate
Muskegon, MI
A Nate, I think you can already answer the question. Unlike with some of the very first XJ Cherokees, I don't think body flex is nearly as much of a concern with Grand Cherokees and later Cherokees as it used to be. Body flex is the twisting of the unibody under hard off-roading, which can cause doors to be hard to open or close. In fact, most of the body flex problems found in unibody Cherokees are duplicable in many 4x4s with frames. I've seen huge 4x4 vans, trucks, and such that had bodylines all distorted from being four-wheeled.
I bet your Grand Cherokee is much stiffer overall than an original flatfender Willy's jeep, which has a frame made to flex and twist. Plus you can tell your hecklers that a unibody is very similar to a tube buggy, only instead of using tube yours is made of sheetmetal. Many professional race cars are unibody designs, and by using sheetmetal (or carbon fiber) they keep the weight down. There are various body stiffeners on the market, as well as upgraded suspensions, body armor, and performance mods for Grand Cherokees, so drive your truck with pride. In fact, the Grand Cherokee has won just about all of the 4x4 of the Year competitions it entered here at Petersen's 4-Wheel & Off-Road magazine. Not too shabby.
The biggest issue with the unibody is that when you try to do an engine swap or custom suspension, the sheetmetal subframe isn't nearly as thick to weld to as a separate frame. But when you consider that there is that elusive '98 5.9L Grand Cherokee out there with 360 ci of power under the hood, I'd say just find it rather than swap in a different engine.
I salute you for driving a 4x4 that is practical for your lifestyle, and for taking your family along when you go four-wheeling. What better way to keep the sport moving forward? I'm choosing you for this month's Nuts, I'm Confused award and will send you the final voucher for a set of tires from General Tire.
General Tire has been supporting our Nuts & Bolts section for the past few months, and we send a big thank-you to them for rewarding our readers with great prizes. We'll be back next month with a new prize, so keep writing in. And to order your own set from General Tire, check out www.generaltire.com
Submission Information
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