Project Fun Buggy - 4Wheel & Off-Road Magazine

If you've been reading this publication over the past two years you've seen the random installments of my Fun Buggy project vehicle. Built out of 300-some feet of DOM tubing, chromoly plate, and a rugged drivetrain, this buggy is destined to be an all-around dirt-chopper. Of course a project like this isn't all perfect weld beads and 90-degree bends. In fact along the way it's had more than a handful of speed bumps and about-faces. To put it simply, building a vehicle from scratch is exciting, challenging, frustrating, and downright exhausting. But it's also great insight on the amount of work the OEMs must go through to build a vehicle that is safe, performs, passes all our governmental regulations, is easily assembled and (if need be) repaired, and most importantly is both sellable and profitable. Hats off to those hundreds of thousands of folks in the auto and truck industry. You've got a tough job.

Since my last installment we not only installed the drivetrain and axles, but also had to cut off and redesign a large portion of the chassis so the best combination of suspension movement and steering geometry within a durable package could be achieved.

There is plenty more work to be done, but here is an update of the current progress.

This is where I left off on the buggy in the previous installment (Feb. '07). The substructure of heat-treated chromoly steel plate was made to attach the suspension links and house the transmission and transfer case, while the main chassis, built of mostly 131/44-inch by 0.120-wall DOM tubing, was growing up off of the substructure. The seating arrangement is leaned back at about 20 degrees for a comfortable ride and a low-slung roofline. Overall height should be around 70 inches with a 19- to 20-inch-high belly.

At the lower portion of the A-pillar and many other places on the chassis, we are integrating multiple tube joints such as this, where one tube bends and three other tubes converge. These points help transfer loads evenly across the chassis, but also require a trained eye to properly notch each tube so that everything fits together tightly prior to being welded.
At the lower portion of the A-pillar and many other places on the chassis, we are integrat
The roof also has multiple tubes to strengthen the chassis and protect the occupants for the day the first rollover comes. These three tubes come together to a point and from there down-bars will run out to midlevel tubes where they will converge with the outer diagonal down-bars.
The roof also has multiple tubes to strengthen the chassis and protect the occupants for t
The front of the chassis has a center windshield tube and top corner gussets to further protect against collapse in a belly-up situation. Also note how the door bars have what I refer to as the vent window tubes acting as gussets for the A-pillar. Many of the internal gussets are made from 1 1/2-inch by 0.120-wall DOM.
The front of the chassis has a center windshield tube and top corner gussets to further pr

The next step was the installation of the Dynatrac ProRock 60 axles, but first we had to prepare the suspension links. Poly Performance is now offering 1 3/4x0.188 chromoly links. The tubing is first cut to length and then the ends are swedged to a smaller diameter. These ends are then threaded internally to 1 1/4-12. Next the links are sent out to be heat-treated to a Rockwell hardness of 35. The heat-treat should make them twice as strong against bending as an identical mild steel link, 150,000-psi ultimate tensile strength to be exact. Into these links are threaded two massive 1 1/4 shank by 1-inch bore FK Bearing rod ends, one end lefthand thread and the other righthand thread for easy adjustment. The high-strength joints are rated to 100,000 pounds of force and are assembled with Teflon liners for long lasting strength and slop-free use. Each joint is also fitted with special high-misalignment spacers to allow for a wider range of motion.

The rear suspension will be a four-link suspension with two upper links converging at the center of the rear axle and two lower links running near the ends of the axle inward slightly to each substructure of the chassis. Since the upper links are less likely to be hitting rocks and other trail obstacles, they will be made of 1 3/4-inch DOM with threaded bungs welded in for the rod ends rather than the more expensive swedged/threaded/heat-treated chromoly lower links. However, all the links will be the same size so that a single spare link can be carried in the unlikely event one is ever broken.
The rear suspension will be a four-link suspension with two upper links converging at the
Where the links attach to the axles are special mounting brackets that Poly Performance custom makes to its specifications. The company offers a complete line of suspension brackets for front and rear suspensions and for swapping coilover shocks and/or different axles under your trail rig whether it be a Jeep TJ, Toyota truck, or custom tube machine like mine.
Where the links attach to the axles are special mounting brackets that Poly Performance cu
My front suspension is a three-link design with a Panhard bar to locate the axle laterally. This design uses two lower links (swedged/threaded/HT chromoly) but just one upper link of the same design as the rear. These will keep the axle from rotating, while still allowing the axle to articulate fully. A Panhard bar will be run laterally with one end on the chassis and the other on the axle. The first step was assembling links and attaching link brackets to the axlehousing before swinging the 565-pound ProRock axles under the chassis.
My front suspension is a three-link design with a Panhard bar to locate the axle laterally

Transmission duties are being done by a TCI-built 700R4. This automatic has a full reverse manual valve body with compression braking features as well as a 2,200-stall converter. Behind that is the venerable Atlas transfer case with a 3.8:1 low range from Advance Adapters. With the 3.06:1 First gear in the 700R4, 3.8:1 low gear in the Atlas, and 5.38:1 gears in the axles, the combined lowest crawl ratio of 62.5:1 should be fine for a fun buggy. This may not seem that low, but we also have the torque multiplication of the torque converter and nearly 500 lb-ft of torque coming from our 383 small-block.
Transmission duties are being done by a TCI-built 700R4. This automatic has a full reverse
With the transmission and transfer case situated, we swung the engine into place. This is the ZZ383 we built back in the Sept. '05 issue (yes, this build is taking a lifetime!). Specs include GM Performance Fast burn heads, ACCEL's DFI super-ram multiport fuel injection, MSD distributor, and Sanderson headers. We built this little torque monster at Scoggin Dickey Performance Center and dyno'd it at 413 hp and 491 lb-ft of torque.
With the transmission and transfer case situated, we swung the engine into place. This is
Locating the engine in the chassis with the axles is a tight fit. We knew we wanted the engine behind the axle for a more even weight balance front to rear, but we don't want to push everything back too far and lose any length on the rear driveshaft. We were able to find just the right position where the centersection clears the crank pulley yet still allows substantial uptravel, articulation, and driveshaft length.
Locating the engine in the chassis with the axles is a tight fit. We knew we wanted the en

Next came finishing the front suspension, setting up the steering, finding a place for our massive yet indispensable Warn 8274-50 winch, and finally locating the radiator in a place with sufficient airflow and protection from trail abuse. This buggy will have a mechanical steering gear on the front axle in case we end up driving it on a long road/wheeling trip such as our annual Ultimate Adventure. Mechanical steering complicates matters since we had to now find places for the drag link, tie rod, and ram assist. By using OTT Industries' high-steer arms, our tie rod (arrow) mounts above the lowest tube of the chassis at full suspension stuff.
Next came finishing the front suspension, setting up the steering, finding a place for our
Returning to the shop the next day, fabricator Drew Burroughs and I determined that some drastic modifications had to be done, and a quick cut of the chassis had the lower framerails removed. Even experienced builders come to situations that require re-examining what they have and making adjustments to gain better performance.
Returning to the shop the next day, fabricator Drew Burroughs and I determined that some d
We decided that the chassis was the part we could change the easiest. With the front end cut open, we pushed the axle up to full stuff and decided that the winch and steering box had to stay put but the radiator would be going to the back of the buggy. The new plan has a tube dropping from the top rail, allowing space for the axle and steering parts to compress. Bumpstop and Panhard mounts tie the upper and lower framerails together. Next I began building a front winch plate for the 8274 using Light Racing's flared hole dies to strengthen the thin chromoly plate. Burroughs handled the welding duties with a Miller TIG machine. As the front of the buggy came together, we realized its face/grille/winch plate is reminiscent of SpongeBob with a demonic flavor, quite fitting for a rowdy fun machine.
We decided that the chassis was the part we could change the easiest. With the front end c

When mounting the drag link and Panhard rod, the goal is to have them as level and as long as possible, so that as the axle articulates it moves very little from side to side. Also keep the mounting points and angle identical to minimize bumpsteer. Since the drag link will be mounted to the top of our high-steer arm, the frame mount had to be down below the lower framerail.
When mounting the drag link and Panhard rod, the goal is to have them as level and as long
With the drag link attaching to the upper steering arm on the knuckle, we decided to try mounting the Panhard bar there as well. This is something we have not seen before, but the idea is that the Panhard mounts to the high-steer arm above the pivot point that is directly above the kingpin where the knuckle rotates. Since the Panhard will be made of chromoly and heat-treated for strength and gusseted in double-shear, the bends shouldn't be a problem. Tune in next time when we'll show the PSC steering install, along with the swing set, captain's chairs, and front and rear shock mounts.
With the drag link attaching to the upper steering arm on the knuckle, we decided to try m

SOURCES
ACCEL DFI www.accel-dfi.com	OTT Industries www.ottindustries.com
Advance Adapters 4320 Aerotech Center Way P.O. Box 247 Paso Robles CA 93446 805-238-7000	Poly Performance N/A www.polyperformance.com
Dynatrac Axles www.dynatrac.com	Sanderson Headers 517 Railroad Ave. South San Francisco CA 94080 800-669-2430 www.sandersonheaders.com
GM Performance Parts TKTK www.gmperformanceparts.com	Scoggin-Dickey Parts Center Lubbock TX N/A www.sdparts.com
Light Racing www.lightracing.com	TCI Automotive 151 Industrial Dr. Ashland MS 38603 662-224-8972 www.tciauto.com
Miller Electric 8-004-AMI-LLER www.millerwelds.com	Warn 5-03/-722-1200 www.warn.com
MSD Ignition El Paso TX 9-15/-857-5200 msdignition.com