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4 Wheel Drive/SUVs/When NOT to use 4WD

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Expert: - 12/12/2007


Question
A friend of mine has a 4WD truck, and in the recent bad weather (snow), her father placed the truck in 4WD mode (specifically 4-Lo, I think). Either way, she continued to drive her truck on the road in 4WD after the snow cleared. Today, the truck started to act up. While in drive,she could move at 5-10mph, and when she simply tapped her brakes, her rear-left tire immediately locked up. The truck seemed very jumpy, but at this point, I had taken it out of 4WD and placed it into 2-Hi on the gearbox. Another friend of hers pointed out that there might be something wrong with her rear-differential. What's your take on this? Thanks.

Answer
Joe,

With the information you have given me, I would check the brakes.  It sounds like something broke or is stuck in the rear brake system.  Possibly a bad or stuck brake cylinder.

Another chance is that something got in a bind (usually the transfer case), and has a failed component.  Anytime you drive in 4WD on a hard surface this will place the transfer case will bind up and drive components will be extremely strained.  Like I said, operating in 4WD on a solid surface usually breaks the transfer case.

Carl

4 Wheel Drive/SUVs

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Carl Brandt

Expertise

Will discuss suspensions, lifts, lockers along with tire suggestions. Trail ratings and possible requirements needed for specific type of trails. Safety equipment and what you should carry with you. Certified off-road instructor. I am not a mechanic, and 4-Wheeling is a hobby, so if I can't answer a technical question it is due to my mechanical knowledge being related to vehicles that I have owned, or have worked on. I do not have manuals on all vehicles.

Experience

40 plus years of 4 wheeling in a variety of vehicles. At the present time, my major off-road rig is a 94 Jeep Wrangler with a spring over and a 1 1/2" suspension lift. This gives me a total lift of 7" or so. I have lockers front and rear. I have removed the track bars, and sway bar for maximum articulation. I am running a stock 2.5 ltr 4 cylinder with a Jacobs ignition along with a cold air high flow filter. It has 4.56:1 gears with a Dodge NV4500 transmission along with a 3.8:1 Atlas II transfer case. This gives me a final ratio of 105:1 in low gear/low range. Other vehicles I own, are a 96 Ford F-250 with a 6" lift, posi rear end, 36" Hummer tires, 5 speed with a fuel injected 460 ci engine, an 87 Samurai with an 8" lift, Ford 9" rear end with a spool, Chevy Dana 44 front end with an electric locker, 5.88 gears, 16% reduction in high range and a 6.5:1 low range with 35" Baja Claws, and a stock 2003 Grand Cherokee Overland. Trails I have run are the Rubicon (10 times), Dusey Ershim, Fordyce Creek trail, McGrew trail, several trails in Moab, Utah along with local monthly runs.

Organizations
Lost Coast 4x4's Cal 4-Wheel Corva UFWDA Blue Ribbon Coalition

Education/Credentials
Certified off-road instructor - Certificates in engineering/electronics

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