Our story so far: JeepSpeed racer Jason LaFortune and his crew at Temper-Mental Racing (TMR) hit us with an intriguing question-could they build a fully operational desert race truck out of a tired, 140,000-mile Forest Service XJ in just 10 days? The pitch was a strong one-LaFortune accomplished a similar feat in 2004, but in 14 days, not 10-and we were curious to find out if he could truly work the same magic in about two-thirds of the time.
In our last issue, we kicked off the buildup coverage with some drivetrain work and frame bracing. During Days 4 and 5, the suspension and rollcage start to take shape.
Day 4: Prior commitments kept us out of the Temper-Mental shop on Day 3, so we had some catching up to do. The most obvious change: the Jeep came off the lift and into the shop's second bay. The lower altitude meant the crew could start locating the axles. At the rear, the Currie 9-Plus racing 9-inch was moved into position. The rearend is fitted with 35-spline axles, 5.14 gears, and a spool. The suspension is cycled with only one leaf on each side.
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Extra engine-mount plates were put in so the engine won't torque itself right out of the frame under race loads. | 
During Day 3, work began on the installation of these Fabtech Dirt Logic bumpstops. Fabtech will also supply Dirt Logic shocks for the Cherokee. |
This Dana 30 was beefed for LaFortune by Sierra Truck & Auto and had been used in his last JeepSpeed truck. The crew is using the 4WD axle for the initial mock-up to make sure nothing interferes with the front driveshaft; the 2WD axle won't have those clearance issues. LaFortune has also spoken with Currie Enterprises about building a custom, 8-inch 4WD front axle that will be much stronger than a built Dana 30 or even a 44. The new axle will be added to the truck as a running change during the season. | 
Speaking of the engine, here's a shot comparing the Jeep's stock exhaust manifold (top) with the 3-into-2-into-1 exhaust header TMR got from Gale Banks Engineering. | 
The rollcage fabrication began in earnest on Day 4. Jon Krellwitz (left) and Jason Rivera (right) check the placement of an over-door tube as Matt McCallum looks on. At this point, all hoops and bars are just clamped into place for test fitting, and the mock-up was done with steel tube. Once Krellwitz and LaFortune were satisfied with the cage's design, those tubes would be duplicated in chromoly. Doing it that way rather than going through trial and error using the chromoly saves 'em a buck or two. |