Trail Gear Rock Assault Axle Housing Axle Swap

Overall, the standard rear Rock Assault housing measures 51 3/8 inches from mounting flange to mounting flange. Each weighs just 54 pounds, includes a drain plug, and comes unpainted and ready for service. Other options like spring perches, shock mounts, and diff breathers are also available through Trail-Gear.

Overall, the standard rear Rock Assault housing measures 51 3/8 inches from mounting flang

When Trail-Gear introduced a whole new concept in axlehousing design, we took notice. After all it's not every day that innovation merges with a proven design like the solid axle. However, at the time we lumped the new offering into the high-dollar category thinking, "sure it's cool, but it probably costs an arm and a leg to purchase." Then about a month later we stumbled upon the price tag online. Would you believe $399? We had to do a double take when we realized that this axlehousing is actually affordable. So we decided an in-depth look was in order.

The exclusive design features axletubes that are offset above the housing centerline of the differential, thus making the inner axleshafts ride closer to the bottom of the tubes rather than in the center.The results are a gain of 3?8 inch of ground clearance under the axletubing. In addition, the stamped-steel centersection offers an additional 3/4 inch of clearance over the factory housing. The axletubes are made from 1/4-inch-thick DOM tubing instead of formed sheet steel and the differential mounting surface is made from 1/2-inch steel plate to ensure studs remain where they should, even under heavy loads.Trail-Gear tells us that each and every Rock Assault housing is precision aligned during and after construction using state-of-the-art, 3D digital imaging equipment. We think this new housing is the cat's meow for all '86-'95 Toyota Pickup or 4Runner owners who want increased durability that won't break the bank. Follow along now as we highlight the swap procedure as performed by Trail-Gear at its Fresno, California, headquarters.

While the new axlehousing was being installed, our donor rig's factory third member was being treated to a traction makeover. We figured since we were going ultra low-buck with this project, a full spool from Randy's Ring & Pinion was the best option. At just $151.62 (at time of print), this is the most economical way to lock a trail-only Toyota rear axle.

Here you can see the stout 1-inch-thick differential mounting flange Trail-Gear includes with each housing. A differential stud kit and RTV silicon are included with the housing. It's recommended that customers degrease the housing inside and out before installation and painting.
Here you can see the stout 1-inch-thick differential mounting flange Trail-Gear includes w
A closer look inside the Rock Assault centersection reveals just three areas when the material is welded. This is beneficial because where there is a weld there is potential for a problem. For this reason the Rock Assault design is superior to that of fabricated plate-style housings.
A closer look inside the Rock Assault centersection reveals just three areas when the mate
Here you can see the outer offset flanges that add to the unique attributes of the Rock Assault housing. Forged from 4130 chromoly to prevent distortion or bending, these stout snouts are designed to hold up to trail abuse.These flanges retain use of the factory bearings and seals.
Here you can see the outer offset flanges that add to the unique attributes of the Rock As

Here is another angle of the forged offset flanges. The factory backing plates bolt right up just like the factory parts.
Here is another angle of the forged offset flanges. The factory backing plates bolt right
Prior to installing the third member into the new housing a bead of silicone sealer was used at the mating surface.
Prior to installing the third member into the new housing a bead of silicone sealer was us
A Yukon spool like the one Trail-Gear installed for us delivers 100-percent traction to both tires all the time and should therefore never be used on pavement. The benefit of this arrangement, aside from low cost, is its simplicity. With a full spool there are no gears, clutches, or moving parts to worry about.
A Yukon spool like the one Trail-Gear installed for us delivers 100-percent traction to bo

Next the third member was married to the new Rock Assault housing.
Next axle perches were welded in place.
A quick coating of paint made the new axle and stock third member look like new again.

As you can see, our donor rig was awaiting the new axlehousing. With a solid front axle already installed, the new Rock Assault rear axle complements this rig's underpinnings quite nicely.
As you can see, our donor rig was awaiting the new axlehousing. With a solid front axle al
A vehicle lift makes installation a breeze. Trail-Gear's technicians simply placed the new housing on jackstands, took measurements to get the unit centered, and lowered the vehicle in place.
A vehicle lift makes installation a breeze. Trail-Gear's technicians simply placed the new
We had Trail-Gear add one of its triple-drilled Toyota flanges with optional dust shield to make sourcing and reversing drivelines much easier. This convenient problem-solver features all common '84-'95 flange patterns in one universal flange. Included are four-cylinder CV and non CV as well as V-6 CV patterns. For just $25 this little guy is a no-brainer.
We had Trail-Gear add one of its triple-drilled Toyota flanges with optional dust shield t

Rock Assult Axlehousing Creeper Breather

Custom Rock Assault Options
This is the Creeper Breather by Trail-Gear. This differential breather kit is favored by professional rock racers because it prevents dirt, debris, and water from entering the axlehousing. The accordion-shaped rubber part expands and contracts to accommodate increase or decrease in housing pressure. No hoses to route and fits snugly on all Toyota Pickup/4Runner solid-axle housings (front or rear).

Fill/Inspection Cap
This extra large differential fill and inspection cap was designed to allow quick access forinspecting the ring gear and/or filling the Rock Assault axle with oil. It features a 1.5-inch-diameter access hole that fits a threaded aluminum cap with rubber O-ring perfectly. Installation requires cutting a hole in the top of the differential housing and welding on a threaded bung. The kit can be ordered loose as a do-it yourself install or it can be ordered as part of the Rock Assault housing at the time of purchase.

Rock Assult Axlehousing Upper Link Mount

Rock Assault Upper Link Mount
Also available for a rear Rock Assault axlehousing is this trick upper-link-mount kit. Designed to accommodate 1.25-inch Currie-made Johnny Joints, this upper link mount can be ordered loose as a do-it-yourself piece, or if desired it can be ordered installed on the Rock Assault housing from the very start.