Jeep CJs, YJs, and TJs are some of the most recognized vehicles on the planet. Known for their unique look and mountain-goat-like agility, they seem to have more fans than Britney Spears. Or the inside of a hovercraft, take your pick.
Like any other mechanical device, or pop star, they do have their quirks. Some are design flaws and some are issues brought on by age and trail use. In this episode of "Weak Links, Strong Fixes" we delve into some of the issues that could face owners of these vehicles. Your experience may vary, but these are some of the issues that the Jeep pros tell us they deal with on a regular basis.
Rear Ended
Weak link: AMC Model 20 two-piece axleshafts
Models affected: '76-'86 CJ
What happens: The Model 20 isn't a bad axle overall (though some may argue that point), and by design it is easier to rebuild and set up than Spicer/Dana axles. Unfortunately, one of its weaknesses is that it uses two-piece axleshafts that are weaker than a comparable one-piece 'shaft because of its outer splines. Larger tires, rough terrain, and the addition of a locker can tax the two-piece axleshafts, often resulting in breakage.
Strong fix: Many manufacturers offer one-piece axleshaft kits for the Model 20. One of those is Randy's Ring & Pinion, and theirs are forged, induction-hardened units made from 1541H alloy. They are available for wide track, narrow track, and (surprise!) Quadra-Trac axles. Each kit comes complete with studs, Timken bearings and National Seal inner and outer seals.
Contact: Randy's Ring & Pinion, 866/245-2316, www.ringpinion.com
Frame Rot
Weak link: Rusty frame
Models affected: '80-'86 CJ
What happens: By design, the stock frames under these rigs tend to accumulate dirt and water. Because the frame is boxed, this captive mixture can flow to the rear of the frame, causing major rust. Attitude Performance in Arlington Heights, Illinois, says that it's not uncommon in the Rust Belt for the rear spring hangers to completely rust off.
Strong fix: You may be able to graft in new frame pieces, but if you're in love with your Jeep, you can replace the entire frame with a new one from a company like Matkins. They offer the Extreme Frame that includes a lifetime warranty and is welded to the specifications of NASCAR and Super Truck. They also offer mandrel-bent Economy Frames. Another option: If your rear spring hangers rust off, you now have a great excuse to convert to a four-link/coilover suspension and skip the leaves altogether.
Contact: Matkins, 406/248-3797, www.matkinsextreme.com
Scrawny Joints
Weak link: Front axleshaft U-joints
Models affected: '72-'86 CJ and '87-'96 YJ
What happens: Most Dana 30 axleshafts used a small Spicer 260-X U-joint, which had a habit of failing regularly. To add insult to injury, collateral damage often included the axleshaft yoke.
Strong fix: Many manufacturers offer upgrade kits for these axles, including Superior Axle & Gear. Their axleshafts are the same spline and diameter, but use a larger 297-X U-joint.
Contact: Superior Axle & Gear, 888/522-2953, www.superioraxle.com
Weak Gearbox
Weak link: SR-4, T-4, and T-5 manual transmissions
Models affected: '82-'86 CJ
What happens: These transmissions were notoriously weak. But hey, at least their gearing was crappy. The result was a gearbox with durability issues and lackluster off-highway performance.
Strong fix: Retrofit is the key word here. Burnsville Off Road in Burnsville, Minnesota, often swaps in a TH400 automatic, while Clemson 4-Wheel Drive Center in Clemson, North Carolina, often utilizes a T-176 (which is actually found in some '80-'83 CJ's). Other options include a Ford T-18, NP435, SM465, SM420, NV3550, or the NV4500. No matter which of these you choose, Advance Adapters offers the bellhousing components and transfer case adapters to make them fit.
Contact: Advance Adapters, 800/350-2223, www.advanceadapters.com