So you're a firm believer in the old adage "real Jeeps have round headlights?" Unless you've got the bucks for a newer TJ or JK, you'd better get cozy with your tool box and welder because older CJ models are plagued with their fair share of issues. We're laying out ten common problems for the '76-'86 CJs, some of which apply to the older '73-'75 intermediate models as well. Since we've covered the earlier '41-'71 Jeeps recently in the story, "Early Iron Addict," (Mar. '10), we'll refer you to our website at jpmagazine.com for the skinny on those models.
The factory CJ pitman arm is made out of ductile cast iron and will probably bend if hard wheeling with larger tires is in the cards. Periodically inspecting the pitman arm nut to make sure it's tight can help prevent the splines from stripping out, but the real problem is the pitman arm itself bending under heavy load. If you want to retain the flat-type arm, you can carry a stock replacement and a pitman arm puller with you on the trail, or look for a thicker arm from a '70s-era GM car in the junkyard. Also, check the heavy-duty replacements offered by one of the many suspension manufacturers out there.
Both the five- and six-bolt external- body locking hubs were held to the hub body with bolts that could (and usually did) work loose with even moderate wheeling. Frequently checking that they're tight, using thread-locking compound, or utilizing the lock-washers won't ensure that you won't suffer a catastrophic failure due to loosening bolts. The best fix is to replace the bolts with studs to equally distribute the load and help prevent loosening. Using lock washers under the stud nuts, and even double-nutting, will provide increased reliability and longevity.
The factory steering shaft coupler at the steering box on your vintage CJ was almost certainly worn out 20 years ago. Today, it can be borderline unsafe. Sloppy steering input and wander are some of the best-case scenarios. The worst-case scenario is that the shaft could separate from the coupler when the Jeep gets twisted off-road. Both Borgeson and Flaming River offer heavy-duty shaft assemblies with solid U-joints that replace the potentially problematic coupler.
Hit any kind of twisted trail with an older Jeep and you'll probably experience the joys of your foot slamming floorboard when you go for the clutch. When the CJ frame and body get twisted up off-road, the poorly designed clutch linkage can come apart. The clutch rods can pull out of the Z-shaped bellcrank and/or the clutch fork. Class M Corporation manufactures a replacement clutch linkage with solid rod ends that won't come apart, no matter how twisted your rig gets. The company offers a kit for both the '72-'75 CJs (PN 7568) or '76-'86 CJs (PN 7560). The company also offers a kit for these CJs sporting up to a 3-inch body lift for these applications by adding "-1" to the end of the part number.
Jeep didn't build CJ frames out of balsa wood, but you'd never know if from any lack of cracking. The frames commonly crack around the steering box and suspension mounts, as well as the front or rear crossmembers. Also, the shackle or spring hangers can crack or snap off the frame. It's a known issue and if you can't afford a complete replacement frame like those offered through Quadratec, 4 Wheel Drive Hardware, or Throttle Down Kustoms, you can purchase weld-in reinforcement plates from M.O.R.E. that will help increase the rigidity and strength of the stock CJ frame.
Check Tomken Machine and JKS for heavy-duty bolt-on shackle hangers to replace the weak, crack-prone factory pieces. Also, ARB and OK 4WD have a kit that includes heavy-duty replacement spring and shackle hangers for the CJ that allows the use of wider 2.5-inch Wrangler springs up front.
If there's one issue that the aftermarket has fully addressed, it's the weenie CJ power steering box mount the factory unfathomably considered adequate. Even with small tires and moderate off-roading, these stock mounts can crack and snap, rendering your steering ineffective. A number of companies, including Sam's Offroad Equipment, Big Daddy Offroad, M.O.R.E., and others, offer heavy-duty replacement box mounts that will never break.
Buzz, Zap, Fizzle
Whether it's an older point-type ignition or the later Motorcraft-sourced electronic ignition, AMC-era V-8 and I-6 engines weren't really known for their stellar ignition systems. Most auto parts stores and catalog shops carry replacement ignition control units for the Motorcraft electronic ignitions, but water, vibration, or just plain bad design can cause those to go out in short order. We've used Performance Distributors' Davis Unified Ignition (DUI) conversion HEI distributors in several of our six- and eight-cylinder AMC-powered projects and have always had stellar results.
Additionally, MSD offers a really nice replacement distributor for Jeep six- and eight-cylinder vehicles. Pertronix makes a good electronic ignition conversion for older Jeep four-, six-, and eight-cylinder points-type distributors, but check to make sure your distributor isn't worn out before ordering.
Junk in da Trunk
We're talking undesirable rear ends here, folks. The AMC Model 20 axles installed in CJ vehicles from '76 through mid-'85 (and some think even mid '86) are barely worth their weight in scrap. Unlike the Model 20 axles found in larger FSJ vehicles, the CJ models featured weak two-piece axleshafts, thin axletubes, and spindly centersections. Virtually every axle manufacturer, including Moser, Randy's Ring & Pinion, Superior, Alloy, and others, offers replacement one-piece shafts.
Still, even with the Model 20's strong ring and pinion the tubes are prone to bending, the centersections are known to snap where the tubes are pressed, or the tubes spin in the centersection bores. It makes a strong argument for swapping a better rear axle assembly if you are planning a gear swap or running a locker and tires larger than 31s.
Sometimes we just want to go back in time and ask the Jeep engineers, "You put what gears in the axles?" And while it's hard to fathom nowadays with all of our unobtrusive emissions-control devices and multi-overdrive transmissions, back in the day the only way Jeep engineers could meet their mileage and emissions targets was to throw obscenely tall gearing at the Jeep's axles in order to lower engine rpm at highway speeds. Many '72-'75s got 3.73 or 4.27 gears, the '76-'79 received 3.54s or 4.10s, and the '80-'86 were saddled with 2.73, 3.07 gears in addition to the other offerings of 3.54, 3.73, or 4.10. So before you order up those 32-, 33-, 35-, or larger tires, give your axle ratios a look-see to make sure your CJ's gearing can handle it.
For the most part, Jeeps of the '70s and '80s didn't come with what we'd call good carburetors. If you scored one with an AMC V-8, you got a great Motorcraft 2100 two-barrel carb, but for the most part the Carter YF one-barrel or BBD two-barrel carbs found on the inline-six engines were sputtering wonders at angles. And don't get us started about the electronic-feedback Carter BBD carbs. If you need to stay emissions-legal and want the best setup for the money, Howell makes a simple and reliable fuel-injection system for virtually any Jeep engine made, with emissions-compliable options available.
If you want low-buck, you can score a two-barrel Motorcraft 2100 off of an older Jeep or Ford car or light truck in the junkyard. Several were made, but look for the one with 1.08-inch venturis for use on Jeep six-cylinders. You'll need a Trans-Dapt small-to-large two-barrel adapter (PN 2086) to change from the Carter two-barrel over to the Motorcraft.