1985 Toyota Truck Rock-Crawler - Project Rock Truggy, Part 1

Jon Bundrant's Rock Truggy.

The ultimate Toyota rockcrawler?

The only things from the ’85 that are reused are the engine, wiring, and cab. Everything else is removed, including the interior, bed, suspension, frame from the cab back, and the roof, which is cut off with air sheers and thrown on the trash heap.

All the tubing used is 4130 chrome moly. The halo bar is 1 3/4-inch 0.120-wall tubing and is both wider and longer than the stock roof for increased headroom and added protection.

In the rear the mounts for the upper suspension links tie into the cage. They have three possible mounting positions to alter the pinion angle for more or less bite, as trail conditions dictate.

Mounts were fabbed on the stock ’85 rear axlehousing for the upper and lower links. The links are 1 1/2-inch 0.156-wall tubing on the upper and 1 3/4-inch 0.120-wall tubing for the lower with Johnny Joints for increased flex. For added strength without extra clearance-robbing diameter, 1 1/2-inch 0.156-wall tubing was hammered into the lower links up to the beginning of the bends.

Nothin’ left but the bare essentials. Bundrant’s background is in circle track, and the lessons he learned there are evident in the cage’s construction as well as the suspension design. The cage incorporates crossbars both front and rear and down bars that tie into the frame.

Here’s the rear cage coming together. One long tube with multiple bends was used as a backbone for the rear instead of cutting and welding several tubes together. It’s clean and super strong, but insanely difficult to pull off cleanly.

Back inside, the floor was cut away enough to make room for the Marlin Crawler dual transfer cases and to allow the gearboxes to be raised for extra ground clearance. Both cases use stock 2.28:1 gears but were upgraded with 23-spline input shafts to match the 4.31 First–geared R151F turbo tranny.

The rear axle is flexed and cycled to check for binding and proper geometry before the final welds are burned in. Notice the added skidplate on the rear axle.

With the rear suspension geometry dialed in, the Doetsch coilover shocks can be fitted and the mounts fabbed up. The coils have a relatively low spring rate, with 400 pounds per inch coils on the bottom and 350 pounds per inch coilds on the top.

The transfer case crossmember was bent up out of 1-inch 0.120-wall square tubing and gusseted with 1-inch stock. The flat tubing provides more surface area on which to weld the skidplate and mounting brackets.

A little All Pro trickery. The rear case employs a custom twin-stick feature that allows the front or rear wheels to be disengaged whether in 4-Hi or 4-Lo. It should be available through All Pro by the time you read this. Next month we’ll tackle the interior, steering, and front suspension. Stay tuned!

Nothing butch, nothing superfluous, nothing tacky. It’s a mean, lightweight bantam with a hankerin’ to do some spankerin’. And that was the original plan.

We’ve been witnesses to plenty of dedicated rockcrawling vehicles that go for the “bigger is better” approach. The ones that really stick out usually sport somewhere in the neighborhood of 400 horses and 40-plus-inch tires and weigh around 6,000-7,000 pounds.

So why not go in the other direction and build the ultimate Toyota rockcrawler? If you’re primarily rockcrawling you really don’t need gobs of power as long as you’ve got low gearing. And if you keep things lightweight, you can get away with smaller axles and drivetrain components. Smaller axles mean you can run a proportionally smaller—and hence lighter—tire size. So, small weight, small power, and smaller rubber mean big performance off road.

When you’re talking Toyota rockcrawling you’re talking All Pro Off Road. They come out with a new and useful Toyota widget as often as Joan Rivers gets a facelift, so we gave owner Jon Bundrant a call. As it turns out, Bundrant was about to embark upon a project eerily similar to what we had envisioned, so we made sure our cameras were there to cover the magic. We’re talking a slinky four-link rear and trick three-link front suspension all supported by coilover shocks. As if that weren’t enough, how about 109:1 gearing, a super-trick twin-stick transfer case, tube work that would make NASCAR jealous, and a fiberglass body that’s cleaner than Martha Stewart’s underwear? And it all rides on some of the coolest rolling stock on the planet. Follow along as we cover the initial stages of the rear suspension, rollcage fabrication, and drivetrain installation. We’ll tease you next month with the interior, axles, steering, and front suspension.