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Geared Down to Get Out

Posted in How To: Transmission Drivetrain on July 25, 2019
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Ford Super Duty axles are arguably the most common setup swapped in to other vehicles, and it is easy to see why. The Super Duty is one of the last vehicles on the market equipped with front and rear solid axles, and the only with a high-pinion Dana 60 frontend. By starting with heavy-duty, eight-lug axles with 35-spline axleshafts we didn't feel is necessary to upgrade shafts or U-joints, even when planning to run 40-inch-tall Milestar Patagonia M/Ts on our fullsize truck.

That doesn't mean there isn't room for improvement, or that all Super Duty axles are created equal. We recently went to Axleline to upgrade the Super Duty axles in our latest project with Yukon components for improved strength and trail prowess. Axleline's head honcho, Aaron Lechner, showed us the strengths and weaknesses of Super Duty axles, along with the changes that have been made over the last 20 years that Ford has been using these axles.

Yukon makes lockers, ring-and-pinion sets, and installation kits for every generation of Dana 60 and Sterling axle. We recommend starting with the newest axles you can find since they have the biggest components to support the increases in power and tow capacity as the Super Duty has evolved. Then just add lockers and low gears and you are ready to hit the trail!

Several different spline counts were used in Dana 60s over the years. Step one is to ensure that you ordered the right parts and your axleshafts fit in the new carrier. It is better to find this out before you go through the hassle of installing the carrier and setting up the gears!
Yukon Gear & Axle makes a variety of limited-slip and locking differentials for axles, including the Dana 60 and Sterling 10.5. We used the company's Grizzly Locker in front (right), which is a full case mechanical locker that provides 100 percent power to both tires while still allowing for disengagement when negotiating turns. In the rear we chose a Zip Locker (left), which is a full case air-operated selectable locker that allows you to switch from an open differential to 100 percent lockup with the flip of a switch.
Note the different shoulder length on the pinion of the new Yukon gear compared to the factory gear. We sourced our installation kits from Yukon with the new gears to ensure that the bearings and crush sleeve would match the gears we are installing. Yukon master install kits include high-quality Timken bearings and all the small parts you need, like new ring gear bolts.
After pressing the old bearings off the factory carriers, we used a flap disc on an air-operated die grinder to open up the inside of the bearings ever so slightly. This allowed us to slide the bearings on the new carriers rather than having to press them on. These setup bearings were used to easily change shims as we set the backlash and preload prior to pressing on the new bearings.
We can't overemphasize the importance of cleanliness when installing new gears. We used brake cleaner to wash out the housing and axletubes prior to installation. This is also the perfect time to replace ancillary items such as inner axle seals. Don't forget to clean the face of the housing, too, prior to reinstalling the differential cover.
The 1480 U-joint is the standard size for Dana 60s. It has a 3-inch body and a 1.375-inch cap size. Super 60 front axles use 1550 U-joints that have the same size caps but a larger, 3.78-inch body that is not only stronger but also allows for more steering angle.
An easy way to tell whether a Super Duty front axle is a Dana 50, Dana 60, or Super 60 is the size of the pinion nut. The Dana 60 and Super 60 will have a 1 5/16-inch pinion nut, while the Dana 50 will have a smaller, 1 1/8-inch pinion nut.
Steering options for ball joint Super Duty front axles is limited compared to older kingpin Dana 60 axles that allow you to easily bolt a steering arm to the top of the knuckle, but there are some weld-on high steer options. The factory arrangement uses a draglink end on top of the mounting point with a long, tapered shank that goes all the way through the knuckle and tie rod.
The toe and heel of the ring gear refer to the inside (near the carrier) and the outside, respectively. The root of the gear refers to the bottom of the teeth, and the crown is the top of the teeth. There are also drive and coast sides to the ring gear. Aaron Lechner of Axleline set up the gears so the pinion teeth would meet the middle of the ring gear teeth to reliably run quiet and smooth.
The Sterling 10.5 rear axle under our truck is a full-floating design, which means that it uses spindles and hubs to support the weight of the truck, just like a frontend. The axleshafts just transfer power from the differential to the wheels. Removing the axleshafts to access the carrier doesn't even require the tires and wheels to be removed.
Early Sterling axles have shorter splines on the pinion than later gearsets have. A long yoke has an overall height of approximately 3 1/2 inches and a spline length of approximately 1 3/4 inches. A short yoke measures approximately 3 1/4 inches in height and has a spline length of approximately 1 1/4 inches. The spline length becomes an issue when swapping gears because the yoke must be matched to the pinion.
Yukon makes installation kits for 10 1/2-inch specific gears as well as kits for the more commonly used 10 1/4-inch gears to retrofit into a 10 1/2-inch housing. The difference is the height of the inner pinion bearing. Yukon offers both bearings, as well as a thick shim to make up the difference between the two in 08-10 axles like ours.
Yukon uses captive shims on its Zip Locker. The thin shims sit under a thick shim on the collar of the seal housing. This makes installation far easier since the thin shims are sandwiched and won't be harmed during installation. Particularly helpful since the Sterling axle doesn't have provisions for a case spreader.
We appreciated that we were able to run the copper air line to the Yukon Zip Locker in our Sterling axle without the need to notch the bearing cap. This is necessary on some applications but it can be tricky to notch enough out of the bearing for clearance and not take so much off as to compromise the cap.
We appreciate that Yukon uses common, easily sourced O-rings on the Zip Locker. It isn't uncommon to cut an O-ring during installation, and these are the biggest culprit of leaks as well.
Rather than install the yoke and crush washer during setup, Aaron Lechner uses this spacer to set the pinion depth and preload. He also reuses the old washer and pinion nut, saving the new components for final installation.
Backlash is the measurement of how close the ring gear is to the pinion. It can be altered by adding or removing shims under the carrier bearings. Lechner noted that the Yukon gears were easy to read a pattern on, making setup easier and faster and resulting in a gearset that runs quiet and cool.
We used a 7/16-inch bit to drill a hole in a flat spot on the top of our Sterling housing. Then the hole was tapped using a 1/4-inch NPT tap to thread the bulkhead fitting in for the Zip Locker.
The final step in the rear was to install the bulkhead fitting and run the air line for the Zip Locker. Yukon includes the solenoid and switch necessary to actuate the locker. We also mounted the company's air compressor. The compact compressor is quiet and small, making it simple to mount.

Super Duty Dana 60s Through the Years
While not as bad as the variations of Dana 44, where zero components from a Dana 44 under a new Wrangler JL are shared with the Dana 44 under a CJ-5, Dana 60s still have quite a bit of variation, even the ones found under Super Duty pickups. Starting in 1999, Super Duty trucks used Dana 50 axles under F-250s and single-rear-wheel (SRW) F-350s. High-pinion Dana 60s were used on dual-rear-wheel (DRW) Dana 60s starting in 2002. These axles had spring perches for leaf springs until 2004 with virtually no axletube sticking out of the casting on the short side, making it a challenge to mount coils or links. In 2005 Ford went to coil springs, along with bigger knuckles and brakes on the Dana 60 front axles. F-450 and F-550 trucks of this era came with "Super 60" front axles that use a larger 10-inch ring gear, 37-spline axleshafts, and 1550 U-joints for even greater strength. These axles have 10-lug adapters, but removing the adapters converts them to the normal Super Duty 8x170 bolt pattern.

Sterling Rears Through the Years
Not all rear Sterling axles are the same, but the differential covers, axleshafts, and carriers are all interchangeable. These are full-floating axles with 1 1/2-inch, 35-spline axleshafts that are very strong. They don't benefit from the third pinion bearing that makes the 14-bolt the king of rear axles though, and the axletubes can spin in the centersection under hard use. Early 1985-1992 Sterling 10 1/4 axles used drum brakes, an 8-on-6 1/2 bolt pattern, and short pinion splines. The second generation (1993-1998) of Sterling axles used longer pinion splines and a different yoke, but were otherwise the same. The introduction of the Super Duty in 1999 brought the introduction of the Sterling 10 1/2-inch, which has a different inner pinion bearing than the Sterling 10 1/4. The 10 1/2 also uses disc brakes and an 8-on-170mm bolt pattern. In 2005 the brakes were upgraded to 13.4-inch brake rotors, and in 2013 they grew even larger to 14.3 inches.


Yukon Gear & Axle
Everett, WA

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