Four Wheeler Magazine

Rrrrrrr...Clink! Those of you who are four-wheeling veterans are probably familiar with evil sounds such as that emanating from drivetrain components. If you recognize this noise, you're also familiar with the distinct pop of a U-joint sending its caps and hundreds of tiny needle bearings off into the trees, or the crisp snap of an axleshaft expiring. Four-wheeling is about going places most other people don't get to see, but no one ever said this privilege is not without costs.

Drivetrain breakage can sour a good day of four-wheeling faster than the sound of steel breaking can echo through a canyon. Since drivetrain is the stuff that links engine power to the ground, a single failure can cut your truck's 'wheeling ability in half or stop it altogether. It's touch and go with drivetrain parts as to whether you'll need a tow back to the trailhead or a quick field fix to continue, and that's why accurate diagnosis is so important. So, to help point you in the right direction when you know something's broken but can't figure out what, we dug through the junk piles at Four X Doctor, Off Road Unlimited, and Tri-County Gear to find prime examples of what commonly broken drivetrain parts look like.

We'll point out what the breakage affects so you can pinpoint the probable cause without tearing everything apart, which failures can be fixed on the trail, and which breakdowns will require a long ride in a tow truck. We'll also point out the weaknesses in certain drivetrain components where applicable. Kick back, relax, and enjoy this pageant of expensive horrors so you can be better prepared when one of your driveline parts turns south.

It's a fact of life that mudding and rockcrawling are hard on a clutch. A worn clutch disc is usually accompanied by an acrid smell (similar to brake smell) while the engine rpm increases but tire speed does not. Also, note the disc is missing a spring, which can cause erratic engagement and more bad noises, and dig a trench in the flywheel. You can often limp to the end of a trail with an expiring clutch, but someone should follow you home.
It's a fact of life that mudding and rockcrawling are hard on a clutch. A worn clutch disc
The chains on chaindriven transfer cases, such as this NP203, are prone to stretch and wear over time. In extreme cases, the chain will loosen enough to jump the sprocket teeth under load. This is usually accompanied by a loud, rapid popping sound as the chain slips. You can sometimes get home when this starts happening if you stay off the throttle, but be aware that continued driving with a loose chain can destroy the entire transfer case.
The chains on chaindriven transfer cases, such as this NP203, are prone to stretch and wea