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A Road-Racing Jeep?

Posted in Events on August 2, 2017
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On a drizzly January afternoon in Monterey, California, Team Petty Cash’s boxy ’89 Jeep Cherokee XJ crests the hill at the Corkscrew, the unmistakable turn at the top of Mazda Raceway Laguna Seca. If the driver wasn’t focused on positioning the Jeep to perfectly slingshot down the 10-story drop from top of the famed racetrack through the twisting curves, he could just catch a glimpse north of the storms in the next valley over. Instead, the Jeep negotiates the Corkscrew and subsequent Rainey Curve with less drama than the score of Mazda Miatas and BMW 3-Series it competes with in the Lucky Dog Racing League. So how have Team Petty Cash taken a two-wheel-drive XJ and made it a competitive dirt-cheap road racer?

The adventure started when former neighbors Jesse Bauman and Matt Adair discovered the 24 Hours of LeMons in 2009 and opted to build what they knew: an XJ Cherokee. Both had owned and driven them for years. Keeping a car running for an endurance race would surely value a tough chassis over outright speed, so they set out to find a beat-on old XJ near the shop where they prepared their King of the Hammers Jeeps in Washington state. Their search turned up a rare (for the Pacific Northwest anyway) two-wheel-drive ’89 on craigslist with 201,000 miles. The white Cherokee’s seller listed it for $500 with the disclaimer that it didn’t run. Adair and Bauman looked at it in person and diagnosed the issue as a grounding problem. They haggled the price to $200, then towed it home and had the 4.0L straight-six running in no time. After adding a six-point rollcage, a racing seat, five-point harness, and a coat of actual “Petty Blue” paint, the newly christened Petty Cash Racing Cherokee ran its first LeMons race in December 2009 at Thunderhill. They finished a respectable 63rd place out of 145 cars. “We didn’t expect to be competitive, we just thought it would be hilarious,” Matt says. “Then we did well in our first race and here we are, seven years later.”

Team Petty Cash driver Matt Adair drifts his Jeep Cherokee XJ out of a wet Turn 11 at Mazda Raceway Laguna Seca during the Lucky Dog Racing League race at the famed California road course.

If You Build It…

After a few races with nearly stock everything, Jesse and Matt decided to make the car handle and brake like a proper racecar. In the front, Petty Cash added adjustable ball joints to increase negative camber, which improved tire wear and grip. The stock front springs remain on the Jeep still, although the team cut off 1 1/2 coils to lower it. To cope with the ride-height change, Adair sourced a beat-up pair of Bilstein shocks of the correct length from a Ford Econoline. In the rear, they moved the leaf-spring shackles from above the axle to below it, which lowered the rear and prevented axle-wrap. To stiffen the rear end, a 3-inch leaf was added. The end result was a Jeep with very little suspension travel in the front or rear, which helps it skate through corners with minimal body roll.

After cutting 1 1/2 coils off the stock springs, Petty Cash sourced rebuilt Ford Econoline Bilstein shocks of the right length. The adjustable ball joint, which allows negative camber in the front suspension, is visible behind the brake line.

The next big upgrade came with the brakes. While adding Jeep TJ knuckles and bearings—which have not been touched more than five years later—they also opted for the Black Magic big-brake swap for a Wrangler, which includes two-piston calipers from a 3/4-ton Dodge pickup and 13.8-inch rotors. That’s a lot of brakes for a vehicle that weighs around 3,100 pounds, and it allows the boxy Jeep to stop better than much lighter cars. The rotor upgrades necessitated bigger wheels. Since brakes, wheels, and tires are exempt from 24 Hours of LeMons’ budget rules, they went big with 17x8 steel Raceline wheels carrying 255/40/17 Falken Azenis RT-615K tires.

The wheels stuck well outside the stock bodywork so Bauman designed fender flares to accommodate the expansive rubber. In the front, the fenders were cut at the top and Bauman tack-welded 3-inch-wide inserts to either side of the cut. This allowed the original mounting points to remain for ease of replacement should a fender get crunched. The rear fenders were designed using CAD (cardboard-assisted design) templates that allowed Bauman to cut the pieces from thin plate steel and weld them to the rear fender.

The increased rotor size required fitting larger wheels and tires, which also improved grip. The wheels are steel 17x8 Raceline wheels with 255/40/17 Falken Azenis RT-615K tires.

The original 4.0L straight-six has developed a reputation for toughness in the off-road community and is generally capable of running without oiling problems despite weird angles. Until putting on the big, sticky Falken tires, Petty Cash Racing had few problems with their XJ’s 4.0. However, they soon found that with grippier tires, the increased lateral Gs in long corners was starving the engine of oil. They cooked three or four engines before adding homebrewed oil-pan baffling and a second-hand Accusump oil accumulator plumbed with actual home-improvement-store plumbing fittings.

After running the stock 4.0L Jeep engine for several years, Team Petty Cash wanted more horsepower. They swapped in a General Motors 5.3L Vortec LM7 V-8. Aside from an $80 Accusump, a scavenged diesel air cleaner, and Griffin radiator, the engine is completely stock.

The transmission remained the AW4 automatic transmission, which the team fit with a manual shifter. The AW4 proved up to endurance racing’s challenge, even withstanding an accidental throw into reverse at 85 mph. In fact, the whole chassis withstood that shock well (the bad shift only ripped off a leaf-spring mount). Everything else—driver’s suit aside—was fine after the wild ride. With the original Jeep engine, Team Petty Cash took home LeMons’ top prize, the Index of Effluency, for the vehicle that does the most with the least, and they also collected a win in LeMons’ Class C. The Cherokee nearly picked up another victory in Class B, though they were foiled by a different kind of unplanned reversal: While leading Class B comfortably at one race, one driver’s pre-driving meal re-emerged all over the inside of the Jeep.

Truckin’

Eventually, Petty Cash Racing decided that while they were happy to pass much of the field in a stock-engine, automatic-equipped Jeep, they wanted to whistle past even more cars. Their next upgrade entailed scoring a 5.3L Chevy LM7 Vortec V-8—commonly known as an iron-block LS engine—from a totaled Chevy Silverado. Knowing they didn’t need any more horsepower than was offered from the stock 5.3, they left the engine untouched. The engine mounts came from Brown Dog Off Road, who worked with Petty Cash as part of their plan to develop an LS swap kit for the XJ. The earliest attempts at racing the V-8 also included an unnecessarily complicated adapter for the AW4.

Petty Cash Racing left the stock intake and exhaust manifolds on their LM7. They’ve eschewed cheap and available bolt-ons because the power and fuel consumption strike a perfect balance to run two-hour race stints at a good pace.

That first engine, however, expired in its first race. After tracing the problem to oiling issues, they were back in business after finding another 5.3 from a Chevy Express Van. A totaled 2001 Camaro gave them a T56 six-speed manual transmission and a better oil pan for the engine. The Accusump was retained and a Griffin radiator fitted, arguably the biggest change made under the hood. Aside from the air filter from a Ford F350 diesel, the intake and exhaust are stock parts. Downstream is a parts-store “Flowmaster” knock-off that normally dumps a single exhaust out the passenger side ahead of the rear tire, although Laguna Seca’s stringent 90-decibel limit necessitated adding a Supertrap. The ECU is a stock tune, though Pacific Fabricators unlocked it to get past all the anti-theft devices in the software. While the original Silverado’s harness was cannibalized to make the engine work, Team Petty Cash also kept much of the Cherokee harness in place to operate things like the brake lights, headlights, windshield wipers, and assorted other electrical items. That leaves parts of two wiring harnesses in, and while it isn’t the prettiest or lightest, it works just the same.

The Vortec originally ran with an adapter for the Jeep’s original AW4 automatic. However, Petty Cash found a crashed ’01 Camaro to donate a T56 six-speed transmission. The team sold the Camaro’s LS1 engine to offset the purchase of the totaled Camaro.

The V-8 presented some clearance issues with the front axle. To accommodate this, Petty Cash cut out the beam axle’s middle section and fabricated beefy square tubing—shaped to clear the oil pan—to link the two remaining sides. The team cut “speed holes” into the square tube to save a pound or two. They eventually also cut a narrow triangle wedge out of that square tubing and welded it back to together; that little bit of angle created increased the negative camber to as much as -6 degrees, though they tend to run closer to -3 degrees.

The two-wheel-drive Cherokee driveshaft amazingly slotted into the T56 and fit into the swapped-in Ford 8.8-inch rear end without modification. A Yukon 3.55-geared limited-slip center section was used, and Petty Cash modified the leaf-spring shackles to fit under the axle to lower the ride height and reduce axle wrap.

The rear axle was also swapped out for a Ford 8.8-inch rear end from a Ford Explorer. That also gave the XJ disc brakes in the rear, which are the stock Explorer setup. The center section of the differential is a GMC Yukon limited-slip unit with 3.55 gears. Bizarrely, the stock two-wheel-drive Cherokee driveshaft slipped right into the T56 and bolted up perfectly to the Ford 8.8. Because those driveshafts are a different length than the 4x4 XJ ’shafts, and therefore rare, Petty Cash keeps a spare driveshaft on hand.

How does it race?

“The lack of suspension travel takes some getting used to,” Adair said. “But it turns great, sticks good, and the brakes are phenomenal. We’ve had pro drivers in this car and they always get out grinning.”

King of the Hammers cofounder Dave Cole drove with Petty Cash at Laguna Seca. He had never road-raced and spent his first hour in the car trying to find his pavement-racing feet. By the time he drove his second stint in the car on Sunday, however, Cole chopped several seconds off his quickest lap and enjoyed blasting past BMWs and Miatas. When he finally emerged from the Jeep after two hours, his smile stretched across his helmet’s open visor.

The Petty Cash Jeep negotiates Mazda Raceway Laguna Seca’s iconic Corkscrew, a two-turn complex that starts a 10-story drop over about a quarter-mile.

Over the years running the Jeep with both the V-8 and 4.0L, Petty Cash have outperformed any expectation for a chassis designed to take abuse off the pavement. Adair credits not only the off-road design but also their off-roading experience to keep the Jeep competitive.

“Durability is key. If you take a [BMW] 3-Series and slide it around, stuff breaks,” Adair said. “But if you take a Jeep designed to go off-road and pull a small trailer, it holds up really well in endurance racing. When things break, our experience with trail fixes—beer cans hose-clamped around radiator hoses and so forth when you’re out in the middle of nowhere—helps keep the thing running.”

Not Dog Tired

The Lucky Dog Racing League weekend started off a bit rough for Team Petty Cash. During a rest stop in Oregon while towing the Jeep from Washington to California for the race, they experienced uncharacteristically cold temperatures, turning the water in the cooling system to slush. Thankfully, it didn’t freeze enough to push out any freeze plugs or burst anything, but nervousness over residual damage lingered all weekend. To top that off, just five miles from Laguna Seca, an emergency stop with the tow rig sent the team’s huge toolbox flying off their open trailer. The resulting cleanup caused them to miss tech inspection, adding another item to their Saturday morning checklist.

The Cherokee came into its own during the rainstorm at Mazda Raceway Laguna Seca. Only a handful of cars were quicker on the wet track.

That left the team scrambling to make Saturday’s race start, but they soon settled into a rhythm with the drivers—Cole, Bauman, Adair, and regular driver Jamie Hutchins—finding a comfortable pace on Saturday to leave enough tread on the Falken tires to cope with the expected rain for Sunday’s seven-hour race. The team finished 14th of 47 starters and 8th in Class B on Saturday. Sunday’s race brought a downpour when Hutchins headed onto the track after the first driver change. The Jeep seemed to relish the rain and despite a bit of contact that brought out a five-minute penalty for Team Petty Cash, Adair hopped in for the final two hours from 12th place. In the rain, only three or four cars went quicker than the XJ and when the Petty Blue Cherokee saw the checkered flag, the team had climbed to 8th place overall and 3rd in Class B, good enough to take home a trophy.

Adair didn’t feel too bad about finishing in “only” 3rd place, especially since the two cars ahead of him in the class were Spec Miatas, cars that can seldom be built for less than $15,000. Not only was Petty Cash racing a Jeep with 1,000 more pounds than a Spec Miata, Adair quipped, “I could build another Jeep like this tomorrow for less than $5,000.”

The Black Magic Wrangler big-brake swap was added to give huge 13.8-inch rotors and two-piston calipers. To keep the brakes from overheating when stopping the 3,100-pound XJ, Petty Cash added plastic funnels under the bumper that channel cool air through dryer ducting directly onto the brake rotors.
To clear the oil pan, Team Petty Cash “notched” the beam axle, using square tubing to link each side of the cut-out section. They later cut a small wedge from the middle and welded it back together. The angle created, coupled with adjustable ball joints, makes camber adjustable from -3 to -6 degrees.
To accommodate wider wheels, Petty Cash fabricator Jesse Bauman cut the front fenders at the top and tack-welded in a 3-inch-wide piece of steel down the fender’s length. That setup retains the original fasteners to ease replacement.
The Cherokee’s minimalist interior includes a Sparco EVO seat with an OMB five-point harness, a homebuilt cool-suit system, and a single-pull fire-suppression system.
Metal shelving donated its life for the custom dashboard. The holes make it easier to mount a variety of items. Left to right: water temperature, tachometer, oil pressure, oil temperature, fuel, fire-bottle pull, switch panel for lights and wipers, (bottom) ignition and electrical kill switch. To the far right are the Rugged Radios radio system and a simple digital clock for stint timing.
Of all the modifications these Jeep enthusiasts have made on their road-racing XJ, none typifies their “trail fix” mentality more than their mirror mount. Team Petty Cash’s made this haphazardly at their first race from a roll of Gorilla Tape and a half-dozen cable ties. It has held the oversized rearview mirror in place for more than seven years.
The Team Petty Cash drivers and crew for the race at Mazda Raceway Laguna Seca (left to right): Jesse Bauman, Bailey Cole, Jamie Hutchins, King of the Hammers founder Dave Cole, Jeepspeed Baja 1000 winner Erik “Camo” Linker, and Matt Adair.
The rear fender flares were designed with cardboard templates (Cardboard-Assisted Design) and welded directly to the rear fenders. The no-name fiberglass wing does very little functionally, but was added as a nod to Richard Petty’s high-winged Plymouth Superbird.
Lucky Dog Racing League limits drivers to two hours in the car at a time. That necessitates quick, efficient driver changes and teamwork to minimize time on pit lane. Note the LED lights mounted inside the bumper cover and the brake ducts below it.
Matt Adair and Jesse Bauman hold up their third-place trophy from the weekend’s second race. They were beat in their class only by cars that cost considerably more to build.
The Team Petty Cash XJ waits in the Laguna Seca garage for another chance to race.

Running With the Dogs

Lucky Dog Racing League began in 2015 as part of the low-budget endurance-racing world started by the 24 Hours of LeMons in 2006. Unlike LeMons, there are no budget restrictions in Lucky Dog. Competition classes are determined by the competitors’ qualifying- or race-pace. The event at Mazda Raceway Laguna Seca featured two races of 6 1/2 and 7 hours on Saturday and Sunday, respectively.

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