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2013 Ford F-250 - Project Super Dirty: Part 4

Front Axle In Place
Fred Williams
| Brand Manager, Petersen’s 4Wheel & Off Road
Posted August 28, 2013

Portal Axle Technology

For the Ultimate Adventure this year we have been building a Ford F-250 at Shaffer’s Off Road in Alameda, California. The goal is a big tough truck to lead our group of four-wheelers over a weeklong off-road trip, the Ultimate Adventure. The F-250 is a great platform because it is a body-on-frame construction, and it has solid axles front and rear and a big diesel engine. Our regular cab longbed truck is a base model with no frills, and we decided to shorten it up into a shortbed to make it more agile off-road. We also opted to keep the stock axles but upgrade them with locking differentials and portal gearboxes. These upgrades will send power to all four wheels when selected and offer 5 inches of additional ground clearance as well as 1 1⁄2 times the axle gearing, perfect for big 40-inch tires.

These upgrades will send power to all four wheels

Though we don’t usually know where Editor-in-Chief Rick Péwé is taking our troop for the UA (our job is to build the truck, he decides where we’re going), we did gamble that this year’s trip may see excessive mud when he mentioned we would want 3-foot-high vent hoses, maybe higher. With deep mud on the mind, we decided portal gearboxes would be a great addition to the Super Dirty. The added ground clearance under the differentials not only helps in rocks but also allows the tires to get down in ruts without plowing the diffs into dirt and muck. This month we’ll show you the axles we built front and rear.

Step By Step

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  • 1. The front axle under the F-250 is a high-pinion Dana 60 with 3.55 gears and an open differential. The axle is a great stock axle with selectable hubs, a high-pinion centersection, big U-joints, strong ball joints, and disc brakes.

  • 2. The first step of converting to the portals was to remove the old inner Cs. The portal gearboxes from Axletech are made to attach to a kingpin-style inner C, so we had to replace the ball joint–style C first. We sourced a set of signature orange inner Cs from Reid Racing.

  • 3. Removing the old C was done with a portable band saw and a plasma cutter. It wasn’t pretty, but it was effective. We left as much axletube as possible.

  • 4. Mike Shaffer devised a plan to sleeve the factory axletube with a short segment of smaller-diameter tubing and then slide the new Reid Racing C onto that sleeve. This would allow us to run a C with a smaller inner diameter for additional strength, and add strength to the tube by increasing the effective wall thickness.

  • 5. Before we knew how long each tube needed to be, we had to decide on inner axleshafts. Nitro Gear & Axle is the official gear and axle of Ultimate Adventure. We went through the company’s listings of axleshafts to decide on an off-the-shelf set of a chromoly 15.96-inch Dodge short shaft and a 38.06-inch chromoly long side shaft from a ’94-’99 Dodge truck. With these known lengths we could determine how much tube to allow on either side.

  • 6. Once tube lengths were set and the inner sleeve installed we heated the Reid Racing C to help it expand and go on the inner axle sleeve with ease.

  • 7. There will be a lot of leverage on the axles, so big beefy welds were burnt into the V-notch of the inner axletube, the inner sleeve and the new C. There were also plug welds through the original inner tube to the inner sleeve.

  • 8. The front axle was set for reassembly with the new Cs. The factory late-model, two-piece inner axle seals didn’t work with our new Nitro axleshafts, so we swapped them out for the older-style, one-piece seals.

  • 9. The axles were stuffed with new ARB Air Lockers. We like ARBs for their ability to engage and disengage the power to each wheel as needed. We didn’t change the axle ring-and-pinion ratio, but we did add new carrier bearings from Nitro.

  • 10. The Axletech portals come with their own front stub shafts, and we fitted them to the inner axles with Nitro’s made-in-the-USA Excaliber U-joints before assembling the front axles.

  • 11. The front axle was also fitted with a new set of kingpins from Nitro with all new bearings and seals. Nitro has a full line of axle building components.

  • 12. Front and rear axles were also fitted with Nitro diff covers. The covers are made of thick aluminum and have fill and drain plugs.

  • 13. The Axletech portals attach to the front axle with a special cast inner knuckle that adapts the gearbox to the Reid Racing C. We added Reid bronze upper bushings instead of the factory plastic style.

  • 14. The steering arms are from Artec, and they have a flat plate inside the arm that will be preloaded to the bronze bushing instead of the normal upper springs. The arms are held in place with five ARP steering studs.

  • 15. The Artec steering arms tie the high steer arm into the standard lower steering arm in either a factory or the Axletech steering knuckle. This keeps the Heim joints on the tie rod and drag link in double shear.

  • 16. The front axleshafts were installed and the Axletech portal boxes bolted on. The portal boxes have four massive gears inside: a drive gear attached to the stub shaft, two idler gears, and a driven gear that attaches to the wheel hub. Final gear ratio is 11⁄2 times the factory 3.55 ring-and-pinion, or 5.32:1, plus the portal adds 5 inches of ground clearance to the differentials. And since the wheel mount surface has been lowered, less suspension lift is required to clear big 40-inch Nittos.

  • 17. The rear Sterling 10.5 axle also received portals, but we needed a rough estimate of how wide the front would be before we could finish building the rear. We started by stripping off the hub, brakes, and old axleshafts.

  • 18. The rear axle was also fitted with a matching ARB Air Locker. Mike Shaffer, proprietor of Shaffers Off Road, has run ARBs in many of his competition vehicles and had the new lockers in without issue.

  • 19. The portals come with new rear axleshafts, and we decided to build the rear axle just slightly narrower than the front. We cut off 6 1⁄2 inches from the end of the spindle, which resulted in the rear axles being 2 inches narrower overall than the front.

  • 20. We mentioned last month how John Bowers machined the end of our axletube perfectly flat; this was in order to attach the rear portal adaptor plates. The adaptor plates need to be perpendicular to the axletube so the portals have zero camber.

  • 21. Before welding the adapter plate to the axletube we slid portions of the rear suspension mounts onto the axletube itself. Then we set the bottom of the portals at level with our determined 3 degrees up of pinion angle.

  • 22. Next we clamped the 1-inch-thick adapter plate to the end of the rear axletube with a through bolt clamp, and Orlando Giannecchinni did a multipass weld to the axletube while the axlehousing was slowly rotated. The massive weld between the thick axletube and the thick adapter plate is strong, but we will eventually add multiple gussets to help strengthen the axlehousing against twisting from the leverage of the portals.

  • 23. The rear axle was allowed to cool and then prepared for reassembly. The 1⁄4-inch plates hanging on the tubes are the start of the rear axle link and coil mounts. We opted for a linked rear suspension to better control the leverage of the portals versus the leaf springs.

  • 24. We assembled the rear suspension mounts, installed the ARB and Nitro diff cover, and mocked up the rear axleshafts. The Axletech rear shafts have extralong splines so we could have built the axle narrower if we wanted to. As it turned out, we only had to trim them 1⁄4 inch to fit.

  • 25. We added the O-ring to the end of the 35-spline axleshaft and slid it into the rear end, then added silicone to the adapter plate and portal box to guarantee against leaks. Dowel pins help align the portals.

  • 26. We buttoned up the axles for now by bolting on the rear portal box. Note the wires to the newly offered speed sensors within the portal. The axles are not light (we guesstimate 700 pounds), but the gearing, strength, reduction of upstream stress by adding the portals, increased traction from the ARBs, and ground clearance all make them perfect for our big truck. Next month we’ll delve into the suspension.


Nitto Tire
Cypress, CA 90630
Ford Motor Company
Dearborn, MI 48126
Offroad Design
Discount Tire
Reid Racing
Pleasant Hill, CA 94523
Warn Industries
Clackamas, OR 97015
Nitro Gear & Axle
Sacramento, CA
Lynnwood, WA 98087
Bubba Rope
Casselberry, FL 32707
Shaffer's Offroad
Alameda, CA 94501
Renton, WA 98057
Synergy Manufacturing
San Luis Obispo, CA 93401
Artec Industries
Off-Road Power Products
BDS Suspension
AxleTech International Motorsports.