Jeep Tech Questions Answered
For the past few Months we've been gathering up your tech questions and taking them to the people building your new 4x4s. We started in January with Dodge, followed by Ford, Toyota, and GM. This month Jeep gives us the answers we all want to know. Next month we'll return to the regular Nuts & Bolts format, so send your tech questions to firstname.lastname@example.org.
Q Why do the European JK Wranglers have a different front bumper design, and where can they be purchased in the U.S.?
A JEEP RESPONDS: Safety regulations are different in the U.S. than in select European countries. We do not make the Euro-spec bumpers available in the U.S. market.
4WOR RESPONDS: Seems reasonable. Maybe there's an aftermarket importing business opportunity there.
The Independent Issue
Q Is independent suspension for the Wrangler inevitable?
A JEEP: There are no plans to change from a live axle on the Wrangler. Solid axles are the foundation of serious off-road performance, the JK's DNA.
4WOR: Excellent! We'd hate to think what would happen to any engineer who tried to change the Jeep Wrangler to IFS.
Totally integrated whozee WhatchaMacallit
Q What is the purpose of the TIPM? This electronic junction box under the hood of the JK seems like it just adds complexity to what should be a simple vehicle.
A JEEP: TIPM stands for Totally Integrated Power Module. This is a computer controlled power distribution system for all electrical vehicle loads. It protects the vehicle's wiring/systems more effectively.
4WOR: This sounds like a fancy way of saying "fuse box." I wonder if you could repair it with a chewing gum wrapper the way you could an old flatfender fuse box? [Ed. note: There isn't a fuse block on a real flatfender Jeep.]
Five-Links in Wrangler's Chain
Q Why do Wranglers use a four-link front suspension with a track bar instead of a three-link front suspension and a track bar?
A JEEP: The five-link suspension design provides the articulation and durability required for serious off-road operation. Fore/aft location of the axles is controlled by the upper and lower control arms. Long, cross-car, front and rear track bars provide lateral location with minimal angle change during suspension travel. Track bar pivots were lowered relative to the axle by 100 mm (4 inches) to lower the roll center as much as practical while maintaining ground clearance. This makes the vehicle more stable. This also helps minimize on-road lateral jostling of occupants for long-term comfort.
4WOR: It's definitely more comfortable than an old leaf-sprung CJ.
Q What are the benefits of an in-tank fuel pump over an external fuel pump?
A JEEP: NVH (noise, vibration, harmonics) and serviceability. An internal fuel pump provides quieter operation, combined with an internal filter that has sufficient capacity to protect the fuel system from contamination for the life of the vehicle in normal service. Without replacement the internal pump offers a better owner experience.
4WOR: Plus an in-tank pump should reduce the operating temperatures of the pump, adding to longevity.
Q I have an old XJ Cherokee. What products does Mopar offer to make my Jeep more capable off-road?
A JEEP: There are a number of great Mopar offerings for XJ owners. New items include an off-road front bumper and the availability of a 4.7L I-6 long-block. The block will fit most Jeep vehicles previously equipped with the 4.0L I-6 engine. Check out www.mopar.com.
4WOR: We saw some very cool Mopar tube doors for the XJ at the SEMA Show also. These SUVs are the best value in the off-road market these days.
Q On the new JK Wrangler you went from steel to plastic fenders. Why? Were these deemed more trail-worthy?
A JEEP: Combining the fender/flair into one unit was the most efficient design for the JK. Fuel economy, safety, and vehicle weight are all aspects that play in the development of a vehicle; it's truly a balancing act. The plastic fenders help us attain goals and meet customer needs.
4WOR: Yes, but our editor-in-chief, Rick Péwé, would like to invite your finest engineers to rest a bottle or can of their favorite beverage on those plastic fender/flares and see if it won't slide off into the dirt. Lightweight is cool, but steel CJ fenders won't dump his Corona on the ground.
Q We know the Jeep JK Dana 44 is different from other Dana 44s. Are the JK Dana 30s different from previous Dana 30s also? If so, what are the differences?
A JEEP: Improvements have been made to the front axles to improve ground clearance, reduce NVH, and improve durability. The driveshaft attaches to the axle at the top (high pinion) instead of at the bottom (low pinion) as on previous front axles to provide greater gear strength when driving forward. Relative to the prior axle, the housing is stronger and more rigid. The pinion bearings are larger to handle added torque requirements created by a heavier vehicle with larger tires. Above-center mounting also reduces the offset between the pinion and the output shaft of the transfer case, thereby reducing driveshaft joint angles for smoother, quieter operation. The JK ring-and-pinion is different from the previous model.
4WOR: It's improvements like these that keeps the Wrangler at the top of the pack for out-of-the-box off-roaders.
Team Tank II
Q Why was the fuel tank moved up beside the driveshaft instead of keeping it behind the rear axle?
A JEEP: The fuel tank location is driven by vehicle packaging to meet functional objectives.
4WOR: "Functional objectives"? Maybe that's marketingspeak for "it removes it from out back where everyone bashes it on rocks." We'd like to see a second tank out back for long-range travel, a diesel engine, a small Jeep pickup, and a smaller solid-axle commuter Jeep that gets 35 mpg, holds two people, and can be used from city streets to ranch pastures.
Confused? Email your questions about trucks, 4x4s, and off-roading tech using "Nuts, I'm confused" as the subject and include a picture (if it's applicable). Digital photos must measure no less than 1600 x 1200 pixels (or two megapixels) and be saved as a TIFF, an EPS, or a maximum-quality JPEG file. Also, I'll be checking the forums on our website (www.4wheeloffroad.com), and if I see a question that I think more of you might want to have answered, I'll print that as well. Otherwise drop it old-school style with the envelope addressed to the address below. Letters published in this magazine reflect the opinions of the writers, and we reserve the right to edit letters for clarity, brevity, or other purposes.
Write to: Nuts & Bolts, 4-Wheel & Off-Road, 831 S. Douglas St., El Segundo, CA 90245 fax to: 310.531.9368
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