Rock Crawler Front Axle Build - Amateur Axle

10. All these gear-supporting features make the Hi 9 equal to, or stronger than, a factory high-pinion Dana 60 even though the ring gear and 9-inch ARB Air Locker are slightly smaller than the Dana 60. Since the 9-inch pinion has more offset from the center line of the ring gear, it also has more tooth contact, meaning all the torque is spread over more teeth compared to a Dana 60. Meanwhile the teeth of the Hi 9 gears are as large or larger than a Dana 60, depending on gear ratio.

11. We routed the copper air line for the ARB Air Locker within the special nodular-iron Hi 9 third member, and Hi 9 recommended running it below the ring gear so as not to interfere with the oiling of the high pinion. Since the Hi 9 uses special gears, it is delivered set up and ready to bolt in, again making this build considerably easier than a Dana axle that must have the gears professionally installed. We also used a forged 1350 yoke for a Daytona-style pinion support from Randy's Ring & Pinion, which added additional strength.

12. Spidertrax offers custom 300M heat-treated chromoly axleshafts that have removable high-angle 4340 yokes. Since we are using a 35-spline Air Locker, we could also have built the housing to fit factory Dana 60 axleshafts to save money, or to carry as spares, though some special machining might have been needed to align the inner seals. We assembled the axle with a set of CTM 300M heat-treated chromoly Dana 60 U-joints. Custom shafts will require a short wait. Note the six-bolt high-steer arms that are also keyed into the knuckle for added strength.

13. We've long been proponents of replacing unit bearings with rebuildable spindle-hub conversions for longevity. But one thing we noticed about unit bearings is just how clean and easy they are to work with should you need to replace a broken axleshaft. The Spidertrax Ultimate 60 knuckles (which can be installed on any 3- or 31/2-inch axletube, by the way) use a Ford Super Duty unit bearing, which is available redrilled to 5-on-51/2, 6-on-51/2, and 8-on-61/2 bolt patterns.

14. Whoops, don't forget to put the third member in before you put the axles and unit bearings in, though it may be easiest to install the third member after the axle is under your 4x4 because it adds most of the weight to your axle. Speaking of weight, a similarly built Spider-9 with Hi 9 weighs roughly 400 pounds. Compared to our high-pinion Dana 60 of equal size and big kingpin knuckles and brakes weighing 560 pounds, that is a serious savings in the unsprung-weight category.

15. Another weight savings aspect of the Spider-9 are these custom 14x3/8-inch rotors and aluminum hats. Ultra lightweight cross-drilled versions are also available as well as thicker custom rotors for heavy vehicles. The jury is still out on whether the 3/8-inch rotors will be enough for a street-driven fullsize truck, but we'll let you know what we find out.

16. Since the axle uses Ford unit bearings there are two choices for locking the axles to the unit bearings. Spidertrax offers these always-locked 4340 chromoly drive flanges with bling blue anodized aluminum caps, or standard selectable locking hubs can be installed.

17. The brake kit from Spidertrax includes Wilwood Dynalite billet four-piston calipers and Polymatrix pads. The combination of large-diameter rotors and multi pistons works great with 40-inch tires on rock-racing buggies, and Spidertrax claims a 23-percent increase in braking versus a standard 113/8-inch rotor. The caliper stand must also be welded to the knuckle but it will clear under a 17-inch wheel. Smaller brakes are available for 16-inch wheels.

18. In addition to the light weight, the 1-ton axleshafts, the high pinion, and the strong gears, the Hi 9/Spider-9 axles also have great steering angles when outfitted with their Ultimate 60 knuckles. The combination of Spidertrax axleshafts and knuckles results in an amazing 50 degrees of steering, while the average Dana 60 is lucky to reach 45. Plus Spidertrax offers an astronomical Ultimate 1550 knuckle that uses big 1550 steering U-joints to reach an unheard-of 60 degrees of steering. Of course this much steering angle can be dangerous on the street, and nearly impossible to utilize with a standard 4x4 frame since the tires will be hitting the suspension at full lock, but if you're building a buggy it should definitely be considered.