The TTB XJ - A Common Cherokee With an Uncommon SuspensionPosted in Features on February 16, 2016 0) (
The first thing you might notice about Eric Filar’s Jeep Cherokee are the giant Ten Factory stickers on the doors. Full disclosure: Eric works for Midwest Truck, which owns Ten Factory, Motive Gear, and Powertrax. But don’t think for a minute though that this is one of those corporate-sponsored builds where a company drops off a vehicle with a shop and then writes a check for the build. “If they did, they probably wouldn’t build a 20-year-old Cherokee with TTB!” Eric quips with his signature dry sense of humor.
Rather than a sales guy who happens to work at an off-road company, Eric is an accomplished fabricator with a background at Avalanche Engineering and Fat City who took a job doing what he loves. He also has done his fair share of Jeepspeed racing with his twin brother, Ryan, so they are very familiar with the Cherokee platform. These days Eric scratches his racing itch by competing with Pistol Pete Sohren of Baja Racing Adventures, which freed up Eric to build a fast Cherokee that fits the whole family but doesn’t necessarily need to conform to any rule book.
Hannemann fiberglass fenders add 6 inches of coverage on each side, along with larger fender openings for increased tire size and wheel travel. The rear fenders are actually intended for a two-door Cherokee, but Eric Filar cut them to fit his four-door. Rear door handles are still a work in progress.
“We were drinking beer in the garage one night and we started taking measurements,” says Eric. “That was when we realized that we could fit the TTB under the Jeep.” Originally built for Jeepspeed competition, the new suspension was way outside of the rulebook and turned the Cherokee into a very fast recreational vehicle instead of a race car.
The front axle is a twin traction beam (TTB) Dana 44 out of a Ford Bronco. Rockcrawlers often pull these axles out in favor of traditional solid axles, but desert racers love them for the huge wheel travel they offer, while retaining 4WD. Eric’s Dana 44 is filled with 5.38 Motive gears, an ARB Air Locker, Ten Factory 4340 chromoly axleshafts, and EBC brakes.
The TTB requires a complicated steering system to eliminate bumpsteer. The Filar twins built their own steering with the steering box moved forward 3 inches. A custom pitman arm on the driver side turns both the draglink that connects to the passenger knuckle and an idler arm on the frame that has another steering link routed to the driver knuckle. A Howe hydraulic rack helps minimize steering effort.
Quality shocks are the biggest factor in traveling off-road at high speed. Eric’s Cherokee uses a 2 1/2-inch, 12-inch-travel King coilover shock with 300- over 400-lb/in Eibach coil springs. The coilover has very light valving, with the 2 1/2-inch, 12-inch-travel, three-tube bypass shock doing the bulk of the damping. This makes it easier to tune the suspension.
The Filar brothers built their own extended radius arms out of 1 3/4x0.120-wall DOM tubing and 1/8-inch plate. The arms use 1 1/4-inch FK rod ends at the “frame” end. The unit body was reinforced with serious amounts of plate and tubing to provide a sturdy foundation for the suspension.
Rolling stock consists of 37-inch Yokohama Geolander AT-S tires that were picked up cheap as race takeoffs. The tires are mounted on 17-inch Raceline Avenger wheels.
Typically we think of a rollcage as a safety feature, but in the case of the unit body Cherokee the cage essentially becomes the chassis of the vehicle. The Filar brothers built the cage out of 1 3/4x0.120-wall DOM tubing and ran it behind the dash. PRP seats and harnesses provide comfort and complement the safety of the cage. The factory rear seat was even recovered to match the tweed of the PRPs.
The extensive tube work under the hood required the inner fenders to be removed. Other than the addition of the ARB air compressor, a Howe steering pump and reservoir, and a K&N open filter intake, the 4.0L engine is completely stock with 140,000 miles on it. A CBR aluminum radiator and triple electric fans keep the engine cool, and an AW4 automatic and an NP231 transfer case get the power to the ground.
The abundant lockable storage offered by the Cherokee platform make them perfect for extended forays into the desert. Eric has an old-school ARB freezer/fridge and a couple Rubbermaid Action Packers, with smaller items shoved into the nooks and crannies.
The rear shock mounts tie into the cage work and allow for a much longer travel shock. The downside is that they are not sealed from the elements. The Filars run King 2 1/2-inch-diameter, 16-inch-travel, three-tube bypass shocks with remote reservoirs for position-sensitive damping.
The rear axle is a trussed Currie F9 9-inch built to Jeepspeed specifications. It has big bearing housing ends, 35-spline Ten Factory 4140 chromoly axleshafts, and Explorer disc brakes. The aluminum third member is filled with 5.37 Motive gears and a Powertrax Grip-Lok locker.
The rear springs are Deaver G9 packs that provide 4 inches of lift. These are the springs that the Filar twins ran with great success in Jeepspeed, so they figured why mess with a good thing?
1998 Jeep Cherokee XJ
Engine: 4.0L I-6
Transmission: AW4 4-speed automatic
Transfer Case: NP231
Front Axle: TTB Dana 44 with 5.38 Motive gears, ARB Air Locker, Ten Factory chromoly axleshafts
Rear Axle: Currie F9 with 5.38 Motive gears, Powertrax Grip-Lok, and 35-spline Ten Factory chromoly axleshafts
Springs & Such: King coilovers and bypass shocks (front); Deaver leaf springs and King bypass shocks (rear)
Tires & Wheels: 37x12.50R17 Yokohama Geolander AT-S tires on 17x9 Raceline Avenger wheels
Steering: Custom “swing set” steering with Howe steering box, pump, reservoir, and hydraulic ram
Lighting: JW Speaker headlights
Other Stuff: Full 1 3/4x0.120 DOM cage, Hannemann fiberglass fenders, PRP suspension seats and harnesses, CBR aluminum radiator and triple electric fans, K&N air filter, Currie Enterprises slip yoke eliminator, Adam’s Driveshaft drivelines (1330 front, 1350 rear), EBC brake pads and rotors, ARB freezer fridge, ARB air compressor