 6.To ensure the best front...  6.To ensure the best front driveline angle possible, we decided to run a high-pinion Toyota electric-locking third member. These units are nice because they come completely assembled and ready to install. |  7. We sourced the above third...  7. We sourced the above third member from West Coast Differentials, along with this Sierra Gear rear ring-and-pinion set, one install kit and all the necessary bearings to complete the installation. |  8.Once the third member was...  8.Once the third member was installed, Toby finished up the front-axle assembly, installing a new set of Longfield Super Axles. We picked these units for several reasons: They retain the stock-style Birfield design and allow up to a 48-degree turn without the annoying steering feedback commonly found with U-joints. They also are said to be the strongest Birfields made. Constructed of 4340 chromoly and 300M steel, they feature smaller balls to allow for a thicker bell and cage. The shafts are also made from 4340 chromoly, and instead of using the standard 27 splines at the Birfield, they use 30. |
9. With the new front axle assembled, Toby positioned it under the truck, checking every detail along the way. Once he felt comfortable with the front driveline angle, he tack-welded the new spring pads in place. He then took a measurement of the front driveline, and then ordered up a pair of CV-equipped driveshafts from South Bay Driveline in San Jose, California. The experts at South Bay Driveline suggested we option in an extra-long slip on the front shaft to prevent problems. The new shafts arrived two days later and looked beautiful. Once the front shaft was installed, Toby completed the final welding on the front axle perches and spring hangers.
10. With 5 inches of lift up front out of the way, it was time to tackle the rear lift. First the rear axle was removed from the truck. Next the gas tank came out. Then Toby installed a pair of Marlin's frenched rear spring hangers into the frame. Though not included in the solid-axle swap kit, we thought these super-clean hangers fit this article well. What they do is prevent the rear spring hangers from hanging up on rocks. To install them, Toby notched the frame with a plasma torch. Then he inserted a hanger and welded it into place. These units are built strong from 1/4-inch-thick plate steel. Once the hangers were in place, the new 5-inch rear leaf springs were installed.
 11. For setup on the rear...  11. For setup on the rear axle, Marlin supplied us with a U-bolt flip kit and a new set of 5-inch-lift leaf packs including spring perches, weld-on shock mounts and new shackles. First, Toby removed the stock spring perches from the rear axle. Next he bolted the new spring packs to the housing loosely to allow for setup of the new rear driveline. Once the proper angle was set, the new rear-axle spring perches were welded to the housing. |  12. With both front and rear...  12. With both front and rear axles now attached to the vehicle,Toby assembled the rear axle and plumbed in the longer brake lines. After a quick brake bleeding, he mounted up the new 35-inch BFG Mud-Terrains on Center Line wheels. These shock hoops (pictured), provided by Marlin, are designed to fit a variety of Toyota trucks. Once the suspension was cycled, the best position was established and the hoops were tack-welded to the frame. Shortly thereafter, the Bilstein 5100 shocks were bolted in. |  This graph was generated by...  This graph was generated by an independent testing facility. It demonstrates the amount of torque it takes to break a Longfield 30-spline Super Axle as well as a standard 35-spline Dana 60 axleshaft. Note how close the breaking point of the Longfield is to the Dana 60s. Keep in mind that the Longfield short shaft failed before the joint itself did. These are some tough Birfields! |
After the installation was complete, we testdrove the 4Runner and found it handled quite nicely on the road. Off-pavement, however, is where the solid axle swap shines brightest.
Total Chaos Fabrication of Corona, California, has been building desert-racing-inspired IFS systems for more than a decade. The company's Gen II Caddy Kit for '86-'95 4WD Toyota trucks increases wheel travel and tire clearance with minimal suspension lift to improve high-speed off-road performance. The chromoly upper and lower A-arms are extended 3.25 inches per side and use 2.5x8-inch-stroke coilover shocks to dampen 12 inches of wheel travel without eliminating four-wheel drive. The setup clears 33-inch tires (with fiberglass fenders), and ride height is adjustable between 2 to 4 inches of lift. As a secondary benefit, these suspension modifications actually improve the ride quality and the truck should handle better than stock.
We ordered a Gen II Caddy Kit from ORW to install on a '89 4Runner to compare the performance of an IFS overhaul to a straight-axle conversion. To complete the installation, we ordered a pair of Racerunner 2.5x8-inch remote-reservoir coilover shocks, two 500x18-inch Eibach coil springs and a pair of fiberglass fenders from Glassworks Unlimited. The truck will ride on 15x8 forged alloy wheels from Alcoa and 33x10.50 BFG tires. Visit www.fourwheeler.com for more information about all the parts and a complete installation.