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Toyota Pickup/4Runner: Solid-Axle Swap: Part 1

Passenger Front Side View
Ben Stewart | Writer
Posted April 19, 2000

Installing a solid-axle-conversion system from All Pro Off Road

Toyota pickups and 4Runners are some of the most reliable 4x4s a buyer can shop for. To go along with that reliability comes genuine 4WD capability. However, for hard-core trail use, the '85 model year is the bull's eye for most buyers.

That was the last year for a solid-axle leaf-sprung front suspension and the first for the fuel-injected 22RE engine. In 1986, Toyota changed its front suspension in this country from a solid-axle leaf-spring design to the independent torsion bar (IFS) design called Hi-Trac. The year 1986 was also the first for the new 3.0L 150hp V-6 engine. In other parts of the world, Toyota continued to sell its pickups with straight front axles. Fortunately for us, this means the bare frame is beefy enough to support a solid-axle frontend without serious reinforcements.

A solid-axle suspension provides numerous advantages over the IFS, not the least of which are increased wheel travel and articulation and large tire durability. It also allows the use of any number of locking differentials or limited-slips in the front axle for added hard-core trail use. All Pro Off Road has been a specialized Toyota builder for many years and has developed a solid-axle-swap system for these IFS Toyotas. The kit works on '86 to '95 Toyota pickups and 4Runners with either the V-6 or four-cylinder engines. Be aware that this is not a bolt-on kit by any means. It requires welding nearly every conversion part to the frame. So an experienced welder should handle the welding portions of the conversion. Although All Pro has converted the newer Toyota Tacomas to leaf springs and a solid axle, it requires much more work, and there is not a kit available at this time.

Our test mule for this conversion was a '92 4Runner daily driver with the 3.0L V-6 and five-speed manual transmission. The swap on this vehicle is the milder of the two offered by All Pro (4-inch pack) and will allow the use of 33-inch tires. The other conversion uses taller springs (6-inch pack) and allows the use of 35- to 36-inch tires. Depending on rear suspension options, both systems should articulate at or near 1,000 on the Ramp Travel Index.

In this first part, we will cover the installation of the solid-axle-conversion system. Next month, we'll ramp the setup, discuss rear suspension options, and perform a full trail test. Stay tuned.

Step By Step

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  • The system comes with all the conversion bracketry needed, Doetsch-Tech Pre-Runner shocks, Alcan spring packs, FJ40 vented disc brakes (needed to retain the V-6 calipers), 1.5-inch wheel spacers, a U-bolt flip kit, shock hoops, greasable shackles, extended stainless steel brake lines, and all the necessary hardware.

  • All the stock IFS bracketry must be removed before the installation begins. Once the brackets are removed from the frame, the entire front section must be ground smooth. This is by far the most time-consuming part of the process.

  • The new All Pro front hanger bracket mounts to the front of the frame temporarily using these center bumper holes. This aligns the hanger bracket properly before welding. Measurements must still be taken, though, to ensure the bracket is centered properly. Ours measured 23/8 inches per side. Take measurements from a few different spots for consistency.

  • Some burrs may be left on the frame horns, so make sure the frame is ground smooth so the bracket fits flush. Once the measurements are checked again, the bracket is tack-welded in place and the measurements are rechecked. Once everything lines up, these frame gussets can be fitted and welded in place.

  • Part of the motor mount and upper control arm bracket needs to be removed, so this plate is welded in place to increase the strength.

  • A jig is included in the kit for placement of the hole for the shackle's frame sleeves. The jig should align 1 inch forward of the body mount.

  • Although it's not necessary, the jig can be welded in place to add strength to the frame. The frame sleeves are beefy 0.250-wall tubing, and when they're aligned properly, they should measure 25 inches between the inside framerails. Since the sleeves stick out more on the outside of the rails, the outside frame measurement must also be taken and rechecked before welding.

  • Once the jig and sleeves are welded in place, the two-piece shackles can be installed. Although these units come with zerk-fitted bolts, be sure to grease the bushings thoroughly prior to installation, and leave them on the loose side until the weight of the vehicle compresses the spring packs.

  • Any 8-inch front axle from a '79-'85 Toyota will work for the swap. However, the '84 and '85 models are the best choice, because they have an added truss on the bottom of the housing. The axle used in this story is the most rare and desirable (as well as expensive) of all. All Pro used an FJ80 high-pinion, reverse-rotation centersection fitted with 4.88:1 gears. The steering arms (red) for the Hy-Steer system bolt directly to any 8-inch knuckle. The vented FJ40 rotors are included in the system and allow the use of the four-piston V-6 calipers. The red skidplate does not come with the system but is offered separately by All Pro.

  • Since the springs will droop more than they will compress, we extended the shocks for 5.5 inches of uptravel and 6.5 inches of downtravel with 1/4 to 1/2 inch of sag factored in, depending on which spring pack was used. With the shocks installed, the location of the hoops was eyeballed and tack-welded, and the measurements were compared with the other side.

  • With the measurements double-checked, the hoops and the additional support arms can be welded in place. If you are unsure of your welding ability, it's best to have an experienced welder help with this step as well as the other welding requirements for this system.

  • The included pitman arm is actually a stock arm machined to accept the much larger FJ80 ball joint. The arm is indexed to line up with the sector shaft on the steering box so it is centered for equal left-to-right steering.

  • Here's a look at the FJ80 tie-rod end compared to a pickup tie-rod end. The All Pro Hy-Steer system replaces the stock tie-rod ends with these and includes a new drag link and a tie rod. It's a great conversion for owners of '79-'85 solid-axle trucks.

  • With the Hy-Steer system installed and all the suspension bolts torqued, we could mount our tires and wheels and hit the trail. Next month, we'll show you how our solid-front-axle 4Runner performed in the outback along with before-and-after RTI ramp testing. FW


All Pro Off Road
Hemet, CA 92543