You may think your Jeep’s undercarriage is well protected because you ordered it with the skidplate option, or maybe you went one step further and bolted on a heavy-duty skidder. But there are some components under your Jeep that a skidplate just won’t protect and you can’t avoid hitting them. Some of these components can take a whack or two but a constant beating from stumps or rocks will eventually wear out anything. So here’s some of the stuff to look out for and some tips on making the abused components under your Jeep last longer than the blade of a grader.
Driveline
Bellhousing: Generally the transmission is protected by a skidplate and there are skidplates available for the engine oil pan. However, what’s in between is usually made of aluminum, left hanging in the breeze, or covered by a cheesey piece of tin. If you have a manual tranny then Lakewood offers 360-degree ¼-inch-thick steel bellhousings that protect the clutch and flywheel teeth, not to mention the crankshaft. As a bonus many of these bellhousings have multiple bolt patterns to make engine swaps a breeze.
Transfer case: So you don’t have a modernized Jeep that everyone and their brother builds bolt-on parts for. If this is your situation chances are your transfer case is made of real iron and has an oil pan. You could drag the case itself from here to Alaska without a problem but the removable oil pan could use some beefing. Take it off and mold a steel plate and bung protector to it, then weld it in place. The next time you go to loosen the drain plug it won’t be friction welded in place and the case will still have oil in it.
Differential covers: The most ground on, bumped, and banged part of your Jeep is probably the bottom of the differentials and the covers. Make sure the cover is ground at least flush with the housing to keep it from being pried up. If your housings are worn down then you can do a little hard-facing like a tractor mechanic. Throw down a few weld beads to build up the material, but don’t weld the cover to the housing.
Driveshafts: Ever seen Hacky McWoodshop shape a piece of wood in a lathe? That’s what your driveshaft looks like spinning in the rocks under your Jeep. The bigger the U-joints and yokes are the longer it will take to destroy them. But U-bolt-style yokes will take more punishment than strap-type yokes. The yoke hardware may become loose from constant grinding so make sure it stays tight. Loose straps and U-bolts could cause vibrations at high speed or even cause the driveshaft to go into orbit under your Jeep. The driveshaft tubes are also susceptible to dents that can lead to twisting or total flinging failure. Some real abusive drivers in nasty terrain have been known to use 3-inch 0.188-wall tubing and bigger for the driveshafts. This will slow down your Jeep’s acceleration a little but you could practically lift your Jeep by the driveshafts alone.
Suspension
Springs: Generally coil springs will be out of the way, but not all leaf springs are created equal. When purchasing leaf springs look for packs that are stacked tightly with no gaps between leaves. Also look for sturdy spring clips. Tin and thin sheetmetal aren’t going to cut it, they can be easily torn off.
Ball Joints: Don’t get greasable lower ball joints for your open knuckle front axle. You’ll only snap off the fittings rendering them ungreasable. The remaining hole will allow water to enter the joint and ruin it. Greasable uppers are OK but difficult to service with the axleshafts in place.
Shocks: Can some shocks take more abuse than others? You bet. Most common shocks have a twin-tube design and a dent or two doesn’t hinder them unless it reaches the second tube where the piston rides. Rancho 9000s have three tubes so they are even more difficult to damage to the point of piston seizure and lock-up. Mono-tube shocks like Bilsteins would seem more prone to damage but they have several advantages over most other shocks. The thickness of the single tubes are greater than the outer tubes commonly found on twin- or triple-tube shocks, they’re made from stronger material (chrome moly), and they can be flipped upside down to get the tubes out of harm’s way.
Exhaust: With all of the engine, tranny, and axle swaps going on you often run out of space for the exhaust. Framerail headers give more room between the framerails but they also put the mufflers in a damage-prone area. Cheesey tin mufflers will crack and fall apart once they are dented. For exhausts that see rocks we’ve had really good luck with Flowmaster mufflers. They’re made of sheet steel, they’re fully welded including the baffles inside, and best of all they don’t come apart when you put a few dents in them. Don’t believe us? The Flowmaster muffler pictured here still works fine.