2004 Toyota Tacoma 4x4 - Solid-Axle SolutionPosted in How To: Transmission Drivetrain on June 9, 2014
After our buddy sold his rockcrawling rig several years ago, he purchased a stock 2004 Toyota Tacoma 4x4 Double Cab TRD. Still very much a ’wheeling enthusiast, he wanted to transform the daily driver into a more substantial trail machine. His rig started out with a basic 3-inch suspension lift and 33-inch-tall tires. Further down the line, he added body armor and a winch. This worked well, but wasn’t anywhere near the vision he ultimately had in mind when he first purchased the Tacoma.
After watching Jon Bundrant, owner of All-Pro Off-Road, and his Tacomas do amazing things over the years, our friend decided to take his rig to the next level with one of All-Pro’s solid-axle conversions. To get the job handled professionally, he headed to Off Road Werkz in Ventura, California, where shop owner Brett Miller and mechanic Christian Gardner assisted with the build. Follow along and see how our buddy transformed his Tacoma and what we learned along the way.
The suspension parts of the All-Pro Off-Road solid-axle conversion include upper and lower links with rod ends, control-arm mounts, track bar bracket and bar (not shown), shock towers, frame strengtheners, front frame supports, and mounting hardware.
The 2.5-inch, 12-inch-travel emulsion shocks from Sway-A-Way are equipped with 7⁄8-inch shafts. The shocks have an extended length of 31.57 inches and compressed length of 19.05 inches, which fits the Tacoma perfectly without cutting into the wheelwell. Each shock was equipped with Swift coil springs. The lower 3.0 springs are 14 inches with a rate of 300 pounds. The upper coil is 14 inches with a 150-pound spring rate.
The All-Pro steering kit comes with a steering box, frame mount and sleeves, pitman arm, Hy-steer arms, FJ-80 rod ends for the draglink and tie rod (not shown), firewall plate, and steering shaft kit.
The Diamond Axle uses V-6 IFS (1988-1995) brake calipers, which were purchased loaded from Marlin Crawler.
Most of the parts used to complete the Diamond front axle were ordered from Marlin Crawler. This includes the high-pinion third member, which was stuffed with 4.88 gears and a Yukon Grizzly locker. Marlin Crawler also refurbished the hubs with 30-spline gears, so they worked with the RCV Performance 30-spline axleshafts.
The conversion began by torching out the entire stock front end. A plasma cutter and grinder make this process much easier. Once the IFS parts are all removed, you must support the frame with a temporary crossmember.
Locate the IFS steering box frame supports and remove sheetmetal, according to the instructions. The measurement is 2 15⁄16 inches from the rear body mount to the center of the front bolt hole. Drill out the frame to fit the two lower sleeves, then weld everything place.
Leaving the stock transfer case crossmember bolted in place, disconnect the rear driveshaft, 4WD harness, and speedometer connector. Next, install the new crossmember using the supplied longer bolts.
After the mount is finished, you can mount the box as shown using the provided hardware. If you have clearance issues at the front of the box, you may need to massage the core support.
Support the transfer case and lift slightly to remove the bushings. Next, weld the support brackets in place.
After you’ve assembled the All-Pro steering shaft and U-joints according to the instructions, leave the upper end off. Next, remove the stock firewall plate and shaft from the steering column. Attach the stock dust boot to the new firewall plate and slide the new shaft up through the hole. Note: The stock steering column splines differ on model years. On the 2004 Tacoma, two keyways had to be made in the U-joint splines for it to fit properly.
Now you can remove the stock transmission mount and crossmember and grind the frame smooth. However, keep at least two of the tranny bolts as they will come in handy later to pull off an exhaust mount trick.
Cut the All-Pro frame strengtheners to fit. This is especially necessary on the driver side because the steering box mount is already in place. Trimming the ends with fish mouths on both sides prevents leaving any vertical weld corners, which tend to stress crack easier. Also, weld in phases and allow time to cool in-between to avoid warping the frame.
Place the passenger-side lower link bracket the same distance from the frame hole as on the other side and tack weld into place. We used a long rod placed through the bolt holes on both mounts and measured using the body mounts to make sure it was square. For now, all brackets are tack welded to ensure all the suspension components can cycle without interference once the axle is located.
Install the All-Pro front frame support 4¼ inches back from the front body mount, as shown. Drain the coolant and cut about an inch off of the lower radiator hose on the driver side for a better fit.
All-Pro had already installed the axle brackets, but before we painted the axle housing, we did a test fit, using a grinder to be sure there was enough clearance in the opening for the high-pinion third member.
The control-arm brackets require welding to the frame. You will need to modify the e-brake cable mount on the driver side. The system is a three-link, so the driver side shares the upper control arm mounting point.
The track bar frame bracket goes on the driver side framerail. Using the side-specific shock towers, place the front edge about 16 ¼ inches back from the body mount. Shock tower location can vary depending on your axle and shock choice.
If your Tacoma has the stock V-6, you will need to install a Toyota T-100 2WD rear-sump oil pan. This is required for steering and track bar link clearance.
Since All-Pro’s 3-inch rear leaf springs were installed with the previous lift, only 2.5-inch longer shackles were needed to bring up the rear.
Once the control arms are installed, be sure to cycle the suspension and check for any clearance issues.
We were able to have our stock front driveshaft lengthened, which saved us serious money on the conversion.
Depending on the Tacoma’s year, your new rear ring-and-pinion gears may come with a different spline on the end of the pinion gear. Luckily, our local driveline shop happened to have this slightly smaller yoke sitting on the shelf. You might want to do a little research and order one ahead of time if need be.
The high-steer system keeps the steering links well out of harm’s way.
For tires and wheels, the Tacoma was fitted with 35x12.50R17LT General Grabbers and mounted on an older set of 17-inch Mickey Thompson Classic series wheels, which were painted black.
Taco Taste Test
Several days after finishing the install, we headed to the desert for a little off-road exploration. First thing, we noticed we needed to trim the fenders more to allow the tires to cycle fully. Luckily, we had predicted this could be an issue during the trip and brought along a cordless Sawzall to trim where needed. With the minor trimming complete, we spent the weekend driving hard and pushing the limits of the double-cab. We had spent so much time before worrying about the more delicate -- and expensive to fix -- independent front suspension, it took awhile to get used to being able to flog the Tacoma without fear of the frontend letting loose.
The wheelbase on our Tacoma is far from short, so the added height improved the breakover angle. One of the biggest challenges when installing a solid axle under a rig originally equipped with IFS is trying to keep it low and retain uptravel. The All-Pro kit does a good job of balancing the needed height, without making the Toyota too tall. It wasn’t the cheapest upgrade, but the total conversion was well worth the off-road performance gains.