Junkyard Challenge Ep. 3: The Game Is Fabrication

Welcome back to Junkyard Challenge. We’re now into the weeds in the middle of build week, as the teams are working themselves into a frenzy. Everyone is running to get their trucks ready in time for the competitions. It’s not quite the 11th hour just yet, but it will be before they know it, and on top of all that, the money is drying up.

In this episode, we’re focusing on the trucks’ drivetrains and rear suspension. No two teams were exactly alike – most went for 4×4, while one chose a 2×4; half of the teams four-linked their rearends, while the other half stuck with leaf springs – and that’s what made this build week so interesting. Innovation and outside-the-box thinking were common to all teams, but the finished products varied wildly.

In this episode, we're checking out what happened on the back halves of the trucks.

It remains to be seen how the choices would play out in the competitions. For now, we can take a closer look at these decisions and why the teams went the way they did. Let’s start with Damage Inc and how they set up their rear suspension and drivetrain.

Damage Inc: Stock rearend, locked differential, four-linked suspension

Artec Industries shock towers (purchased through the team’s Summit Racing budget) were used on all four corners of the F-250.

Let’s review – Damage Inc chose a 1989 Ford F-250 as their build truck. As the oldest truck of the bunch, it carried with it some front end advantages (stout motor, twin traction beam suspension) but some serious rearend drawbacks (leaf sprung, open differential). Setting it up for competition would require some work.

Once the bed was out of the way, getting the rearend out of the truck was simple enough. With a few bolts and some brake lines removed, the axle came out without much fuss. The team started cutting off leaf spring mounts, as the decision was made to go to a four-linked setup with Fabtech long-travel coilovers, Hyperco springs, and FK rod ends. Versus a leaf-sprung setup, four-linking offers some unique advantages. It comes at the cost of build time, but the improvements to the suspension are worth the trouble.

Leaf Springs Or Links?

For the trucks of Junkyard Challenge, half of the teams – Damage Inc (above, right) and RSO – chose to go the four-linking route. They would enjoy greater shock travel and axle articulation, which would come in handy for the short course and barrel race. Lighter weight was also a factor worth considering, which goes to a linked setup more than a leaf setup. It would also handle the jump contest well, as links and coils tend to do better with sudden impacts.

On the flipside, retaining the leaf springs saved precious time for Teams NexGen (above, left) and RaceAnything. They saved money as well, and the simplicity of dealing with a factory-designed leaf spring pack cannot be overstated; linked setups are notoriously complicated and time-consuming, requiring extensive fabrication and forethought. This was evident in watching the other three teams hash out their setups for multiple days, while Nexgen and RaceAnything’s setups took significantly less time.

The rearend itself factors into the performance of a truck. Gearing and locking functionality make impacts on acceleration, top speed, and cornering grip. Damage Inc opted to retain the stock gearing for the truck, but did weld the differential’s spider gears to turn it into a full-time locker.

Locking the differential permanently is something that all teams went for, and for good reason – constant power to both wheels meant no slippage coming out of corners or going over obstacles. The methods changed from team to team (see Team NexGen’s solution below), but all could agree that locking up the rear was the way to go.

Damage Inc's rearend came together beautifully. It was beefed up by welding the differential, welding the axle tubes and truss, and a four-link system capable of great shock travel.

One final change to Damage Inc’s rearend was the addition of an axle truss, made by Artec Industries and bought through the team’s Summit Racing budget. Axle trusses make an arc over the pumpkin and connect the tubes to rigid metal. This prevents the axle from bending or cracking during hard landings and extreme driving. To bolster this, Damage Inc also welded up the axle tubes to the pumpkin.

RSO: Stock rearend, locked differential, four-linked suspension

Over at Team RSO, that old rear setup had to go. Leaf-sprung and clapped out, the guys got to work tearing down the back half of the truck. As the only two-wheel-drive truck in Junkyard Challenge, the yellow shirts had their work cut out for them. They had to prove that the 2WD Dodge Ram could keep up with the rest of the 4WD contenders.

To that end, the team changed from the leaf springs to a four-link/coilover setup. They also formed a truss to strengthen the rearend, much like Damage Inc. Billy Sykes handled that duty. “She’s a little dirty, so in order to get our truss welded on, we have to get all the nasty crap off of it,” he explained. Tackling that involved a steel brush on a die grinder, which would give the truss pure, clean metal to weld to.

As for the gearing, RSO opted to upgrade the truck with a 4.88:1 ring and pinion from Yukon Gear and Axle. Tyler welded the spider gears in the diff to make it a locker.

Billy cleaned up the axle for welding. Mike got busy fabricating the truss, and then Billy welded it on. He used cardboard cutouts to get an idea for what shape to make gussets, which would help reinforce the truss.

Once the truss was in place, numerous mock-ups and preparations came next. The geometry on a linked suspension has to be spot-on, or else it risks having erratic handling – not to mention driveline issues. The rearend needs to be centered properly with triangulation of the links or by a Panhard bar. And if the pinion angle is off severely it will be difficult to keep the driveshaft attached to the pinion. Once the planning was done, the team welded in the upper and lower mounts for the links. The upper links welded inside the “C” of the frame, while the lower ones welded to the bottom of the frame.

On all suspension setups, teams had to do what’s called suspension cycling. This showed the maximum upward and downward travel of the tire, coinciding with the shocks’ compression and extension. It gave the build teams an idea on how much clearance there was for the tires, as well as what kind of load (side to side, forward and backward, etc.) would affect the coilovers. On the black Dodge, it was as good as it could ever be.

RSO's rearend takes shape. Cycling the suspension (top right) ensured the geometry was right on the money.

Fabtech Dirt Logic 2.5 Shock Choices

Damage Inc’s F-250: 12-inch front coilovers (PN FCS1208) and 18-inch rear coilovers (PN FCS 1211) with Hyperco springs

Rock Solid Offroad Ram 1500: 8-inch travel front coilovers (PN FCS1206) and 14-inch rear coilovers (PN FCS1209) with Hyperco springs

Race Anything’s GMC 2500: 12-inch front coilovers (PN FCS1208) with Hyperco springs and 14-inch rear shocks (PN FCS1221)

Nexgen’s F-150: 12-inch front coilovers (PN FCS1208) with Hyperco springs and 18-inch rear shocks (PN FCS1223)

RaceAnything: Stock rearend, locked differential, leaf-sprung suspension

Keeping the leaf-sprung rear unaffected (for the most part), Team RaceAnything went against conventional SoCal thinking. Their approach – solid front axle, big tires, and weight reduced as much as possible – ran counter to the approaches of the other teams, who wanted to emphasize shock travel over raw power.

Still, the rearend would need beefing up to survive the competitions. After removing the bed, the guys hacked it apart to cut down on weight. As for the frame, some improvisation was in order. A requirement of the Junkyard Challenge was that the trucks maintain the appearance of a truck, body panels and all. So the guys fashioned some metal pieces from the bumper into spars that held the bedsides in place, and mounted them to the frame.

The rearend received a welded diff (a.k.a. "Miller locker") to keep the axles locked together while driving. It would be perfect for the loose dirt coming up in the competitions.

The 4.10:1 rearend was pulled apart. Inside, the stock differential was extracted and welded to lock the axles together. “We tore it apart to weld it up,” said Jeff. “We put it back together with some fresh Lucas gear oil, and that was it.”

On the leaf springs, the team took the overload spring out and added an arched add-a-leaf (bought through Summit). “Doing that gave the flat stock spring a little lift to essentially give us more bump travel,” said Jeff. “And it was easy and quick, which is always nice.”

The team didn’t change any of the shackle points, but did cut off the bump stops to get more up travel.  The leaf spring only bolstered by a Fabtech shock. So ended the rearend setup for the white GMC.

NexGen: Moser 9-inch rearend, locked differential, leaf-sprung suspension

On the NexGen F-150, the team wanted a fully built axle housing that could handle the demands of competition. For that, they splurged on a choice axle made by Moser Engineering. “We paired it with a U.S. Gear 5.29:1 ring and pinion,” said Chris Nissley. “We used Moser axles and a Moser 3rd member.”

To replace the stock 8.8 housing, NexGen went for a used Ford 9-inch housing with Moser guts. This is a tried and true axle design, well-known for use in everything from drag racing to hot rods. Its main appeal is the 3rd member, which can be removed from the housing and tinkered with in the open.

Such is what Kris did, swapping to a Moser spool differential in the process. “We wanted something stronger than the 8.8 and its C-clip axles,” said Kris Steele. “The 9-inch 3rd member design also keeps the gears together better due to having three pinion bearings, so the pinion can’t move anywhere.”

Kris assembles the Moser 3rd member. As a spool differential, it would lock the axles full-time. This offered better traction in the dirt. Meanwhile, the team also installed a set of used Deaver springs and converted the axle to a spring-under instead of spring-over design.

This setup was a spool by default, so the axle shafts would lock and spin in unison like all the other trucks. This one just happened to be a bit more elegant than welding the gears together. “The spool gives equal power to both wheels,” said Kris. “There’s nothing that’s gonna fail like a spider gear weld, a ‘Miller weld’ like the other guys did. Using an actual spool was a lot stronger.”

As for the leaf springs, these were Deaver 64s. “We went to a spring-under design instead of the stock spring-over design,” said Chris. “This cuts down on axle wrap and allows us to use a longer spring and therefore get more wheel travel out of it. It also melds well with our goals after this competition, since we plan to use the truck to go racing.”

From the new fuel cell to the K&N fuel filter to the Moser 9-inch, the F-150 was not lacking in upgrades.

As mentioned before, the team stayed true to the leaf spring setup on the truck. However, the old fuel tank was ripped out in favor of a fuel cell from JAZ Products. This was supplemented with an Aeromotive fuel pump and K&N fuel filter, making sure the engine would receive reliable, strong fuel flow, even in turns and coming down from a jump.

That’s gonna do it for Episode 3. Each of these teams is in high gear, trying to outpace the others and come out ahead. The trucks have to be built to take on punishment and still make it to the end. But will all of them reach that point? You’ll have to stay tuned to find out!

The 2019 season of Horsepower Wars is made possible by some of the leading companies in our industry, including K&N FiltersSummit RacingToyo Tires, COMP CamsTCIMAHLE MotorsportsDyna-BattWeld RacingCorsa PerformanceFragolaHolleyDiabloSport, NOSE3 Spark PlugsTotal SealMickey ThompsonMoser EngineeringBMR SuspensionMiller ElectricAerospace ComponentsVictor ReinzMorosoUS GearHawk PerformanceLucas OilPRW IndustriesVP RacingProCharger, and ARP. Stay tuned for the Junkyard Challenge. It’s going to be a wild ride!

About the author

David Chick

David Chick comes to us ready for adventure. With passions that span clean and fast Corvettes all the way to down and dirty off-road vehicles (just ask him about his dream Jurassic Park Explorer), David's eclectic tastes lend well to his multiple automotive writing passions.
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