I have wanted to build a rock buggy for years now, but the problem is that I don't know how. I'm fairly good with wrenches, and I'm not bad with a welder, but I've never built a complete buggy from scratch. So it would be pretty dumb of me to tell you how to do it, unless I worked with some of the most experienced folks in the business and showed you what we did. The plan here is simple, build a sicko rig that can be hammered and hammered hard until I learn to drive better, and hopefully cover everything we do so you can copy it. I don't expect to see a hundred clones of my Fun Buggy on the trail next year, but if you can steal a few tricks or ideas here and there, then this whole project will be worthwhile. If you decide you need to have the exact same thing, I'm sure all the shops and suppliers in these articles will gladly build said parts for you. I know this is going to be expensive for most of you, but I also know that many of us like to read about the super-cool gnarly stuff even if we will never do it ourselves. (Why do you think Playboy magazine is so successful?) So here is the compromise, for every part I install I'll try to give a cheaper alternative. I may not use the budget bits in my buggy, but I also don't want you to think that the high-dollar way is the only way to go. I've seen tons of cheap-built wheelers out there, and I believe that 90 percent of what I'll be building can be duplicated with other parts.
This month we will start with the axles. I have laid awake many nights trying to decide what would be best for my buggy. Toyota axles can be built tough, but I want to run at least 37-inch tires and preferably 40s, 42s, 44s, or 47s. Rockwells are cool, but this thing needs to see highway miles and I'm not fond of that axle's weight. The 9-inch axles are pretty tough, but I'm a little concerned about the smaller ring gear. Portals are awesome, the ground clearance can't be beat, and I was really close to having custom 9-inch/Mogs built, but I have also seen them break, and the maintenance parts are not available at your local NAPA. So I returned to Dana 60s. Yes, we've done that before, but 60s are also axles that anyone can get at their local junkyard. However, I decided to build the toughest Dana 60s available. Let me get this out of the way right off, this is not an entry into Cheap Truck Challenge. These parts are some of the best you can assemble into an axle, and other than the brakes and some of the gears and bearings, they are all a step beyond a stock Dana 60, and as such they are not inexpensive. I am having the front built to standard Ford high-pinion widths-69 1/2 inches wheel mount to wheel mount-so you could copy it. My rear axle is a high-pinion rear-steer axle, an axle never available in a production vehicle, but there are other options. My first choice in junkyard rear axles would be a GM 14-bolt, after that a Dana 60 or 70. Folks here at the office have said that I don't need rear steer, but my argument is I also don't "need" to go wheeling, but I want to, and I want rear steer. I've seen it live in a 9,000-pound Avalanche, so I think it will be fine in a buggy that's half that weight. Plus it is fun to play with, and that's the whole point of this rig, having fun.
If you want to see more photos of this buggy buildup and read more about what I'm doing to get it on the trail and road, be sure to follow along on our Web site (www.4wheeloffroad.com), where I will be doing updates. Plus feel free to e-mail me any questions or comments you might have at firstname.lastname@example.org.
1. The Dynatrac Pro Rock 60 housing is often touted for having more ground clearance than a Dana 44 housing, but that's not the reason I chose it. I figured that ground clearance is good, but I can always adjust my line to keep moving up the trail. In fact, I was ready to use a junkyard 60 housing for my front axle when I started looking at the part of the housing where the axletubes are pressed in, and realized just how much thinner they are than the Pro Rock housing. Notice the holes drilled for the plug welds; the stock housing is just 1/4 inch thick where the Pro Rock is just over 1/2 inch. That-and the fact that the Pro Rock was specifically designed with abusive four-wheeling in mind, where the Dana unit was built for moderate four-wheeling (do you think the Dana engineers ever imagined their axle being driven up a rock cliff in Johnson Valley or Moab under a 1-ton truck?)-was enough for me.
2. Dynatrac usually builds all its axles with ball-joint knuckles, and despite abusing the front and rear steering axle in the Ultimate Avalanche as well as driving it for 50,000 miles, I have never had any problem with them. However, this time I decided to go with the older-style kingpin knuckles. The reason was that I wanted these axles to be similar to what the average wheeler could get his hands on. Since I was looking to upgrade from stock, I got four new forged inner Cs and cast knuckles from Dedenbear. They both have had material added over the stock design to strengthen them, and the crew at Dynatrac quickly welded on new pieces of 3 1/8-inch DOM tubing with 1/2-inch wall thickness, 1/8 inch thicker than stock.
3. The tubes are machined so that they have a tight fit when pressed together, and the pinion angle and caster must be known before assembly. In the front I went with 6 degrees up in the pinion angle, and 6 degrees back in caster. This should allow good driveshaft angles without affecting steering return to center at speed. In the rear I went with 0 degree caster with 0 degree pinion angle. Then if the pinion is turned up to point toward the transfer case, it will give the knuckles more positive caster. However, rear-steer caster is less important since it will not be used at high speeds.
4. With the housing pressed together and welded, it was finally time to install the guts. One thing I decided to do is upgrade to 40-spline axleshafts. Most Dana 60 steering axles come with 1.5-inch 35-spline inner axles and 1.28-inch 30-spline outer stub axles. My 40-spline shafts measure 1.71 inches in diameter and are made by Superior Axle and Gear from 4340 chromoly. In matching material, stepping from 35-spline (top) to 40-spline (bottom) is equal to nearly a 50 percent increase in torsional strength, and going to chromoly increases that even further. Superior makes these shafts here in the United States and sells them exclusively through Dynatrac. Dynatrac is working on an upgrade kit to make any kingpin or 35-spline Dana 60 accept 40 splines.