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Techline - January 2014

Jeep Cherokee Xj
Ali Mansour
| Brand Manager, 4WD & Sport Utility
Posted December 12, 2013
Photographers: Four Wheeler Staff

Your latest Tech Questions Answered

Clearly Appealing
I have a ’95 GMC Jimmy that the clearcoat is peeling in spots. I want to rattle-bomb (spray paint) the outside similar to how you did the Rescued Wrangler. Are there any precautions or tips I need to know?
Kyle Hunter
Via email

If the clearcoat is peeling heavily in areas, use 120- or 150-grit sandpaper on it. Once the area is smoothed out, spray on a coat of automotive primer. The goal is to build back the area you knocked down. Before I paint, I like to go over the rig with an orbital sander with a 320-grit pad. Be sure to wipe the rig down well with acetone before painting as well.

Limit Straps and IFS
I have an ’03 Ford Explorer XLT that’s four-wheel drive and rides on 32-inch-tall tires. I want it to be a good all-around on- and off-road SUV. Before someone says I should just buy a Jeep, I am 7-foot and 300 pounds. I have not found a Jeep that I can even fit in. The Explorer I fit in just fine. I just put on BTF’s 3-inch leveling spacers and they suggested I install limit straps. How do I know which kind and size needed?

Would it be better to install taller springs and struts? I was also wondering about wheel spacers. Maybe after I install a 3-inch body lift I could put on a 35- or 37-inch tire. Would the spacers affect the axle gearing in addition to the taller tire size? On the subject of IFS and IRS, will parts from any straight-axle rig work, or are there any specific axle manufactures that make better parts for them? I am still deciding on whether to install limited-slips or selectable lockers. I noticed on the ARB website that they only list a locker for the rear of my Explorer, so that may be my only option.
Richard Schlee
Via email

A limit strap works exactly as you would imagine it would. The strap’s sole purpose is to limit the suspension travel so it does not overextend and cause damage to the drivetrain and suspension components. Finding out what length of limit strap you will need requires drooping or decompressing the suspension to the point just before the suspension and driveline components are in a bind. While limiting your suspension travel may sound counterproductive for an off-road rig, it is actually a smart way to preserve your rig’s parts. You won’t go far off-road with a broken 4x4.

Most limit straps require welding on tabs to which the straps actually bolt to. As you alter your rig, it is possible to swap out the strap lengths to increase or decrease the amount of travel. The position at which you mount the limit straps and tabs will also factor in to what length you will need. Companies such as Poly Performance (www.polyperformance.com) offer a variety of lengths and types of limit straps that can be used on your application.

Wheel spacers will not affect your gearing, though spacing your rims out will alter the vehicle’s stance and turning radius. The aftermarket for your generation Explorer hasn’t quite taken off like the early-gen SUVs, but it seems to be getting better. As far as aftermarket axle upgrades, RCV Performance (www.rcvperformace.com) is currently your best option. RCV specializes in custom high-angle CV axleshafts that can accommodate large amounts of travel as well as handle the stress loads of a larger tire. An ARB Air Locker (www.arbusa.com) placed in the rear of your rig would be money well spent over a limited slip, as the locking action of the differential when engaged will deliver more performance gains off-road.

Front Blocks
Please disregard if this is a stupid question, but I would like to know why I can’t run front lift blocks? In Florida, I see a bunch of guys using them on mud trucks. I have been told I just need to weld the block to the axle and that it will be OK. I am 16 and looking to build my first mud truck. Lift kits are expensive and it seems like lift blocks would be a cheaper way to lift my Blazer for now.
Ethan Bellmore
Via email

I completely understand how the allure of an inexpensive lift can draw you in. I too have encountered sky-high mud rigs with front lift blocks and cringed at some of the “home brewed” engineering that survives under the mega-swamp machines. To understand why front lift blocks are dangerous and a bad idea, you simply need to look at it from a basic physics perspective. Whether driving off-road or cruising down the freeway, your vehicle creates a certain amount of rolling momentum. Whenever the brakes are applied, nearly 70 percent of the vehicle’s weight is transferred forward, putting extreme stress on the front axle and suspension components.

When you add a front block into the equation, it elevates the leverage point on the front axle, causing the caster-shift to become even more dramatic. These forces can be enough to actually expel the front block out from between the axle and leaf spring. As you can imagine, an ejecting lift block can result in extreme damage to you, your rig, and presumably anyone in a close proximity. Sure, some argue that welding the front blocks to the axle can eliminate the block from shooting out.

The main issue is that welding cast material isn’t easy and generally requires someone with experience and the correct tools to create a safe and reliable weld. Even with the block welded, it doesn’t change the fact that the higher perch has increased the leverage point on the axle. Raising the leaf-spring mount on the front axle will also intensify the effects of lateral force, which can make for sketchy handling on- and off-road. Axlewrap, along with increased spring deflection are another set of issues now lumped in with the blocks. Ultimately, front lift blocks are dangerous and not worth the time and risk.

Military Axles
I’ve been trying to find good quality Axletech military axles. I’m located in Canto, Georgia, and in need of four axles, for two rigs I’m building. Any suggestions or advice would be greatly appreciated.
Holden Byess
Via Email

I would contact Memphis Equipment as it is the closest to your location. The company can be reached at 901/774-0600, www.memphisequipment.com. If the company does not have what you are looking for you can start moving farther west with Red River Parts & Equipment (903/547-2226, www.redriverparts.com), which is based out of Texarkana, Texas, or you can contact Boyce Equipment (800/748-4269, www.boyceequipment.com), which is in Ogden, Utah.

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