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1981 Toyota Trekker - Import Upgrades: Part 1

Digging Into The Axles Of Our First-Gen Toyota 4x4

John CappaPhotographer, Writer

Our ’81 Toyota Trekker 4x4 featured most of the popular aftermarket suspension, steering, and axle upgrades. The truck worked great as a trail crawler. As our interest in going fast over rough desert terrain increased, we began to realize that our truck was too narrow, too tall, and too unstable to drive aggressively at any real speed. Our suspension travel was also limited by our leaf springs. We were ready to take our Toyota to the next level. To do this, we needed to dig into the axles and into the suspension. We started with the axles of our project in this installment, and in the next installment, we’ll dive in and give you a closer look at the suspension modifications we made.

Only a handful of axles enjoy enough aftermarket support that a completely new axle assembly can be built from scratch. Trail-Gear is the only company that has fully embraced the Toyota solid axles from end to end. The company offers everything from beefy hub upgrades, to improved knuckle seals, heavy-duty bolt-in housings, and even complete turnkey axle assemblies. Trail-Gear also offers the heavy-duty Rock Assault housings for Suzuki Samurai and Ford 9-inch applications.

Our axles already had some good useable parts that would bolt right up to the Trail-Gear Rock Assault housings, so we decided to reuse some of these components. If you’re on a budget, you don’t have to make all of these mods at once. The good news is that all of these upgrades can be added to your existing axles. You can pick and choose only the Trail-Gear axle parts that you need, and nearly all of these heavy-duty hard parts come with a no-questions-asked lifetime warranty. Here is what we put together for our speedy, crawling, do-it-all, off-road, first-gen Toyota. Check back next issue when we’ll be hanging them under the chassis with a long-travel, go-fast suspension.

The Rock Assault axlehousings feature massive 3-inch-diameter, 5⁄16-inch-thick, 1020 DOM axletubes, and the centersections are made from press-formed 1⁄4-inch plate steel with a 1⁄2-inch-thick third-member mounting surface. This design allows you to simply weld suspension brackets wherever they are needed without a special welding process. A weld-on axle truss is also available for ham-fisted bashers.

In addition to high-clearance shaved centersections that provide 3⁄4-inch more ground clearance than stock, the Trail-Gear Rock Assault axlehousings feature offset outer ends to provide an additional 3/8-inch of ground clearance under the axle assembly. Every little bit helps to keep us off the rocks and moving forward.

For even more bend resistance, the Rock Assault axletubes are internally gusseted. This is the kind of strengthening and attention to detail that is typically reserved for expensive full-race rearends. Trail-Gear internally gussets all front and rear Rock Assault axlehousings.

We stuffed our rear Tacoma-width Rock Assault housing with Trail-Gear heavy-duty 4340 chromoly axleshafts. The ’shafts have an ultimate break strength of 8,300 lb-ft and come with a no-questions-asked lifetime warranty. They are designed for the factory Toyota wheel studs. Aftermarket studs will require that the stud holes be opened up a bit for them to fully seat. Do not force aftermarket studs in place with a press or you could damage the axle flange.

We capped off our rear axle with a Trail-Gear Tacoma rear disc brake kit. The kit includes the rotors, CNC-cut mounting brackets, calipers, pads, DOT-compliant brake lines, and even the conversion fittings required to make the swap.

The Rock Assault housings are designed to work with all of your original Toyota components. However, whatever old Toyota parts you don’t use for your conversion can be easily sold to recoup some of the upgrade costs.

You can order your Trail-Gear Rock Assault axlehousings for a standard third member or for the factory electronic locking differential third member. Each housing comes complete with new mounting studs. Our repurposed front and rear third members bolted right into the Trail Gear housings without issue.

The Rock Assault front Toyota housings feature the same shaved centersection and offset axle ends as our rear axle. We ordered a Tacoma-width, passenger-drop front housing for our project, but several widths and suspension options in both driver- and passenger-drop versions are available. The knuckle balls are forged from 1035 steel, making them much stronger than stock, which eliminates bent knuckle-ball issues.

For the most extreme steering knuckle strength, we decided to swap out the factory failure-prone trunnion bearings for the Trail-Gear Rock Assault Trunnion Bearing Eliminator Kit. This kit replaces the bearings with greaseable kingpin-style pins that sit in hardened bushings.

Thanks in part to our ram-assist steering, we have broken many steering arm studs, even high-strength aftermarket studs. The Trail-Gear Six Shooter knuckles and steering arms offer much more material and two more studs to keep the steering arms in place. These knuckles and steering arms can be bolted up to any solid Toyota front axle.

The wider Rock Assault front axlehousings come complete with the necessary chromoly inner ’shafts, depending on the width you select. We opted for the heavy-duty 30-spline inner shafts and Trail-Gear Longfield 30-spline polished 4340 chromoly outer axleshafts. This combination brings our Toyota’s axleshaft strength up to and beyond stock 1-ton Dana 60 axleshaft strength, but in a much smaller and more lightweight package.

Abusive drivers with big tires will appreciate the heavy-duty Trail-Gear spindles. They are forged from a solid chunk of 4140 chromoly and then CNC precision machined as a direct replacement for all ’79-’85 solid-axle Toyota 4x4s.

Anyone who has fussed with loosened or broken locking hub studs or busted-up locking hubs, will appreciate the Trail-Gear Longfield Studless Hub kit. The Studless Hub kit replaces your stock Toyota bearing hubs and manual locking hubs with a chromoly bearing hub that features an internal-spline design, similar to a 1-ton Dana 60. The new bearing hub is designed to work with IFS brake rotors, calipers, and wheel studs, so you’ll need to add those to your upgrade list as well.

The Longfield Studless Hub kit includes a beefy chromoly drive flange that can be easily removed to disengage the front axle for longer on-road trips. All you have to do is pop in the drive flanges when you are ready to hit the trail.

The Studless Hub assembly is capped with an O-ring-sealed billet aluminum cap that keeps water, dirt, and grime out of the wheel bearings.

We simplified the sealing on the backside of our knuckles with the Trail-Gear Trail Safe knuckle ball wiper seal kit (left). These seals are made from seal-grade polyurethane and replace all of the leaky stock rubber and felt components (right). As you can imagine, installation is a lot quicker and easier, and you’ll never have to wipe clumps of grease from your knuckles again. The dual seal surface keeps the dirt out and the grease in.