Weak link: Front axle
Models affected: All
Two front axles were used under the TJ. All non-Rubicon TJs got the Dana 30 and Rubicon-equipped rigs got the Dana 44. When either of these axles are fit with 35-inch-and-up-diameter tires and subjected to moderate-to-hard trail use, the axletubes can bend at the differential and the inner "C"s can bend as well. This problem is similar to the one found in the wider JK Dana 30 and Dana 44 axles that we covered in the story "Support Group," page 66 (Mar. '09). The bent components can cause the front tires to tilt inward at the top (negative camber) and there can be gaps between the ball joints.
Strong fix: These housings are expensive, so the best course of action is to stop the damage from happening before it starts. Off Road Evolution and Burnsville Off Road are a couple of companies that offer kits to strengthen these axles. Pictured here are the EVO Magnum sleeves from Off Road Evolution. They install inside the factory axletubes to increase strength by 30 percent and they include dual seals to keep dirt and debris out of the axletubes. Off Road Evolution also offers axle gussets to reinforce the "C"s.
Contact: Off Road Evolution, 714/870-5515, www.offroadevolution.com; Burnsville Off Road, 952/890-3990, www.burnsvilleoffroad.com
Weak link: Dana 35C rear axle
Models affected: All, as equipped
What happens: The Dana 35C is a notorious axle. It's relatively reliable for stock use on the street, but its fragility becomes quite apparent when you add larger tires and hit the trail. It's not unusual for the housing to bend, the differential to grenade, or the axleshafts to break-sometimes all at the same time.
Strong fix: Swapping in a beefier Dana 44 or Ford 8.8 axle is common. With one of these installed you can typically ply the rough stuff with up to 35-inch tires. If you've formed some sort of bond with your Dana 35C and can't bear to let it go, many aftermarket companies offer products to beef the 35C. Randy's Ring & Pinion offers the Ultimate 35 kit which includes two Yukon heavy-duty alloy 30-spline axleshafts, carrier bearings, studs, axle bearings, and shims. You can choose between an array of lockers, including their Yukon Grizzly Locker or their Zip Locker.
Contact: Randy's Ring & Pinion, 866/631-0196, www.ringpinion.com
Chill Out, Power Up
Weak link: Mechanical fan
Models affected: All 4.0L-equipped vehicles
What happens: The mechanical fan on 4.0L-equipped TJs sucks power from the engine, decreasing performance and fuel economy.
Strong fix: Swap to an electric fan. There are numerous options available, but Dan McKeag at Burnsville Off Road says they routinely swap out the mechanical fan for the electric fan used on '03-up, four-cylinder-equipped TJs. McKeag says it's a large unit that bolts in and helps the engine produce about 15 more horsepower. When Burnsville does these swaps, they utilize a Derale Performance adjustable fan controller with thread-in probe (shown). This controller has a maximum capacity of 25 amps, an adjustable fan activation range from 150 degrees to 240 degrees F, and a heavy-duty relay.
Contact: Burnsville Off Road, 952/890-3990, www.burnsvilleoffroad.com; Derale Performance, www.derale.com
Corrosion Is Closer Than It Appears
Weak link: Outside rear view mirrors
Models affected: '97-'02
What happens: The base of the factory outside rear view mirrors is made of pot metal and corrodes easily. We know, because we purchased a '97 TJ new and ours corroded after just one Midwest winter. While the corrosion doesn't seem to have an effect on structural integrity, it looks awful.
Strong fix: In '03, Jeep switched to non-corroding plastic molded outside rear view mirrors. They are a direct bolt-on and can be ordered through a Jeep dealer or found at a salvage yard.
Contact: Do-it-yourself fix