The Art Of Building Custom DriveshaftsPosted in How To: Transmission Drivetrain on August 1, 2011
Whether you’re a competitive rock racer or a free-spirited overlander, two mechanical devices control your fate in the rough. That’s right—driveshafts and their components are what govern your vehicle’s ability to move about in the many environments of planet earth (unless, of course, your rig is powered by nonconventional means like electric motors or hydraulics). Also known as propeller shafts, these cylindrical torque-transmitters come in numerous configurations, from the simple one-piece type to complex multi-segmented units that are engineered for acute operating angles, massive suspension flex and/or high torque loads. In many cases, the OEM driveshafts found under your 4x4 will do the trick, but once you lift your vehicle to fit larger tires, increase power or gearing with engine and drivetrain swaps, or simply take your rig to places where modified vehicles prevail, custom-built units are the only way to go.
One of the most prolific builders of custom driveshafts today is Tom Wood of Ogden, Utah. Wood and his crew of skilled shaft-smiths have built a reputation for quality and customer service that very few can equal. For more than 12 years, Wood has refined his recipe for producing driveshafts that can handle the worst sections of trail, and then head back out on the highway for high-rpm operation free of vibration and disruptive harmonics. All shafts produced by Wood’s company leave via prepaid carrier, and nearly 98 percent of all business conducted is from locations outside of his home state. To their credit, no two driveshaft formulas are the same, and despite hundreds of thousands of applications, they continue to grow their shaft-specific database, which they refer to as the “recipe book.”
Last summer, we took a trip to investigate precisely how Wood’s legendary shafts are made. The following pages contain the highlights we discovered along the way.
Once the customer’s requirements are determined, an in-depth build sheet is completed, leaving no detail to chance. Items such as tubing size, wall thickness, yoke type, and segment length are just some of the many metrics that get scrutinized.
The next step of the process is gathering the necessary componentry from Wood’s extensive collection of flanges, yokes, slip sections, and joints.
With all the individual components collected, the technician directs his attention to pulling and cutting the drawn-over-mandrel steel tubing that makes up the body of the driveshaft. Tubing comes in a variety of sizes with varying wall thicknesses.
Next, the tubing is placed up in a special lathe so that it can be squared and chamfered for weld integrity.
Once each component is mocked up and square, an MIG welder is deployed to join the individual sections together.
Here you can see a custom-made tool that is used to ensure that the slip section of the shaft is timed correctly with the component on the opposite side of the shaft. This step is critical to the balance of the assembly.
Once each corresponding section is welded to the tubing, the technician must check the shaft for warpage using a dial indicator. Warpage is caused by the heat of the welder. To counteract this, heat is applied to the unit in precise areas to bring the out-of-round condition back to spec. Here, you can see the technician applying heat to the section in question.
Once the shaft meets the strict tolerances set by Tom Wood’s, the technician moved on to the final assembly area. Here, the shaft receives a particular end flange or yoke, depending on vehicle application.
This photo shows an assortment of flange types offered by Tom Wood’s for Jeep JK applications.
With the end flanges secured to the driveshaft, the unit is moved to the balancing machine. The balancing process starts by cleaning the driveshaft; an optional polished finish begins by removing surface oxides. To do so, the technician uses 120-grit sandpaper to brush the exterior surface of the shaft. The balancing machine spins the unit while the technician guides the sandpaper across the surface. This produces a clean, brushed finish.
Next, the balancing machine spins the unit to determine where weight is needed to achieve balance. Weights are taped to the areas in question, and the machine repeats the process to see if the temporary weight corrects the imbalance or not.
Once the weight is in the correct location, the technician welds the weights in place on the shaft.
With the shaft properly balanced, the technician applies a coat of laquer or paint to protect the metal from corrosion.
Next, the various sections of the assembly are greased with high-quality Dynalife extreme-pressure grease.
After greasing, the unit is readied for shipping. Here you can see the process by which the shaft is wrapped in plastic prior to boxing. Each day, Tom Wood’s ships upwards of 20 driveshafts to all corners of the world.
Like your trail rig, driveshafts come in all types and sizes. Tom Wood’s can build just about any size shaft you need, from 1.25- to 4-inch diameter and with lengths ranging from 10 inches up to six feet. All it takes is a quick phone call to figure out what type and size of shaft you need for your 4x4.
Innovation by Design
One of the many innovations Tom Wood made possible is the Superflex U-joint shown here. Unlike traditional driveshaft U-joints, the Superflex joint features an offset cross section that enables ten degrees more flexibility than is otherwise obtainable. Superflex joints come in three sizes: 1310, 1350, and 1410, and they help eliminate binding that can occur when driveshaft angles exceed 30 degrees. While not a cure-all for all high-angle applications, the Superflex U-joint is well suited for dedicated trail rigs that do not regularly operate at highway speeds
Tom’s a Wheeler, Too
Just like you, Tom Wood is a 4x4 enthusiast with a passion for exploring our country’s numerous trail systems. We regularly run into Wood at events such as Easter Jeep Safari and the Tierra Del Sol Desert Safari. This photo shows Wood enjoying a trek through the lush forests of northern Washington State during Trail Tour 2010. His ’85 Jeep CJ-5 sports a 401ci V-8, built Dana 44 axles and (of course) a pair of his own custom driveshafts.