Jeep Wrangler TJ Buyers Guide - Mr. Popularity

Engines
When you look at the CJs of yore or even the YJs that preceded them, TJ Wranglers could possibly represent the best build fodder the off-road enthusiast was ever presented. Unlike the YJs there were no awkward early years with undesirable drivetrains. Right out of the gate in '97 until the model was discontinued in 2006, Jeep's venerable and ubiquitous 4.0L six-cylinder was offered with very little change. Beginning in 2000 Jeep ditched the simple, but crack-prone tubular exhaust manifold for one with integrated, twin catalytic converters, which makes header upgrades somewhat more expensive. Also in 2000, all Jeep 4.0L engines went to a coil-on-plug ignition system, thus doing away with the distributor and plug wires, and then in 2005 the 4.0L got a revised throttle body. Otherwise through the model run, power and torque numbers on the 4.0Ls are similar, with no significant changes. Four-cylinder engines were the sturdy and almost-adequate 2.5L until Jeep's new DOHC 2.4L appeared in 2003, upping the base engine's available power from 120hp/181lb-ft to 147hp/190lb-ft. Regardless, either four-cylinder is disappointing once a lift and tires are added, so it's still best to hold out for a 4.0L model if you plan on bigger tires, adding armor, and doing more than rock crawling with your TJ.

Transmissions
For the most part, behind the engines Jeep wised up and did away with lackluster transmissions. Aside from the mealy AX-5 ('97-'02) or the NV1500 ('03-'06) five-speed manual tranny found behind the four-cylinder engines, any TJ transmission could be considered a keeper even with a mild V-8 swap. The AX-15 five-speed was used behind the 4.0L up through 2000 when it was phased out for the studly NV3550 five-speed. The NSG 370 six-speed tranny that appeared in 2005 behind the 4.0L has a lower torque rating than either five-speed that preceded it, so just because there's one extra gear, don't automatically assume it's one better than the AX-15 or NV3550. And speaking of automatically, if you prefer to let the tranny do the shifting, you're stuck without an overdrive up through the 2002 model year, because the three-speed Chrysler 32RH was the only game in town until the overdrive four-speed 42RLE came to town in 2003.

T-Case, Axles, & Steering
The T-case in any standard TJ is going to be the excellent NV231J with 2.72:1 Low, which like the TJ itself, enjoys an arsenal of aftermarket support. Axles in standard TJs are low-pinion Dana 30s in the front with no center axle disconnect and 3.07, 3.55, or 3.73 gears for six-cylinder or 4.10 cogs for the four-cylinders. Out back, all four-cylinder models got the Dana 35, while the Dana 44 with 30-spline shafts was available on six-cylinder Sahara and some Wrangler X trim levels. The Dana 44 is a real boon and can same you a lot of money on a mildly-build vehicle. The low-pinion TJ Dana 30 can be replaced with a high-pinion Dana 30 from an XJ for a little more strength since it's a bolt-in swap. All TJs run the same steering setup that employs a J-bend at the passenger-side tie rod to clear the knuckle at full-turn. This is a very common problem spot, so check for a previously-bent and straightened links if the vehicle you're looking at looks like it's been wheeled hard.

Check When Purchasing:
•T-case slip yoke output seal leaking
•T-case linkage shifts smoothly and without binding
•Leaking at axle tube ends, pinion seals, diff covers
•Smashed front diff cover
•Peeled back rear diff cover
•Any excessive slop or play from the rear axle (especially Dana 35 models)
•Bent, broken, worn steering linkages