The five-lug, 14-bolt rear axle.
There are thousands of GM 14-bolt axles rusting away under pickups and vans across the country. They can often be snagged for $50 complete. Measured from wheel-mounting surfaces, a single-wheel pickup truck axle comes in at 67 1/2-inches, a van axle at 70 inches, and a dual-rear wheel truck at 72 inches. For off-road use, the 14-bolt's biggest drawback is its huge centersection and its eight-lug hub design with huge drum brakes. However, there are ways around these problems. And if you factor in the axle's humongous 10 1/2-inch ring gear, 30-spline, 1 1/2-inch shafts, and beefy 3 1/4-inch axletubes it starts to look attractive.
Our original plan was to yank an axle from the junkyard and cobble it together for our '48 Willys project vehicle for under $500. Maybe we could have done it and maybe not. Point is, our time is worth something to us, so we decided to let a professional axle builder set up our 14-bolt for us.
We originally called Wayne Wilcox of Geartech Heavy Duty to inquire about his company's aluminum 5x5.5-inch and 6x5.5-inch aluminum conversion hubs for the 14-bolt. After a few minutes on the phone with Wilcox and hearing about his disc-brake conversion kit, optional upgrades, and the fact that he had several 1-ton axles sitting on racks, including the 70-inch van 14-bolt we wanted to use, we were sold. Geartech HD builds all sorts of drivetrain components, from custom Dana 60 front axles using Rock Crusher components, to NV4500 transmissions, to T-cases, to everything in between. Check out how Geartech HD built us a better 14-bolt.
Even if you're ordering a used axle from Geartech, it's like new when it arrives at your door. The company chucked our axle in a lathe to turn the tubes smooth after knocking off the stock spring perches and mounting tabs. The company's 14-bolt disc brake conversion can use standard Chevy 1/2-ton calipers (shown) or e-brake equipped calipers.
New on the market, Geartech's heavy-duty diff cover is cast of 1/2-inch-thick cast steel and weighs in at 37 pounds. There's no way we're going to peel back the lip of this cover on a rock. Even though we chose not to have Geartech perform this operation, the diff cover is designed to add rigidity to housings that are shaved for high ground clearance.
We ordered a set of 5.13 gears from Motive Gear and a Detroit Locker and shipped them to Geartech for installation. The inside of the housing was spotless and fully painted, just like new. The Motive Gears are of the highest quality, and the increased turning afforded by the Detroit will let us swing the 120+-inch wheelbase better than a spool on the trails.
Geartech's aluminum conversion hubs are available for Dana 60 and 14-bolt, eight-lug axles. The hubs make it possible to run either 5x5.5 or 6x5.5 bolt patterns on the 1-ton axles. The 14-bolt hubs are built to stock single-wheel specs. Using these hubs on a dual-wheel 14-bolt would result in a substantial increase of track width.
Although the stock 14-bolt shafts are big, we have heard of them breaking because the metallurgy isn't the greatest on the planet. To ensure we don't suffer a trail failure with 40-inch tires, a 184:1 crawl ratio, and 600lb-ft of twist, Geartech upgraded to a set of beautiful Dutchman Chromoly axleshafts that have the same hat outside diameter as the hubs for use with standard rims.
Finally, the Achilles heel of stock 1410-series 14-bolt yokes is the fact that only the weaker strap type is available. We ordered this 1410-series U-bolt style yoke from High Angle Driveline for the ultimate in strength and reassurance when the right foot comes down.