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Techline: Your Top 4x4 and Off-Road Tech Questions Answered Here

Posted in How To: Tech Qa on July 29, 2019
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Bronco Shoe Fitting
I'm looking for what size lift and tires would be most practical under my '92 Bronco XLT with a 5.0L V-8. I've seen other Broncos around with a 2-inch leveling kit and 33-inch tires, but everything I read says go with a 4-inch lift for 33s. If 31-inch tires are my stock size, then shouldn't 33s fit with a leveling kit and 35s fit with a 4-inch lift? I'm also wondering how well Gladiator X Comp M/T tires work off-road. I live in Alaska so there's not much rock, just mud and dirt with a bit of sand. How do the X Comps compare to the Federal Couragia M/Ts? Also, is there a way to build a spare tire rack off of the stock rear bumper?
Aiden Willets
Via email

All trim levels of the '92 Bronco, which include the Custom, Eddie Bauer, XL, and XLT, will allow fitment of 31x10.50R15 tires. As with most vehicles, fitting larger tires will depend on wheel width and backspacing, how much lift you have, and how much you are willing to trim from the fenders, bumper, and inner wheelwells. In most cases, lift kit manufacturers recommend 1.5 to 2 inches of lift and some fender trimming to fit 33x12.50 tires on your Bronco, although some narrow 33-inch tire and wheel packages will fit a stock Bronco. The 4-inch lifts will typically fit up to a 35-inch tire with some trimming. Of course, you can fit much larger tires with these lifts if you are willing to trim more. Also, aftermarket cutout fender flares such as those from Bushwacker (bushwacker.com) and fiberglass fenders from companies like Autofab (autofab.com) will allow for even larger tire sizes.

Tire selection is a tricky process. We can't really choose a specific tire that would be best for your application, but we can point you in the direction of tire features to look for. Given that you live in an area that sees a lot of snow and ice, it would be a good idea to look for a mud tire that has at least some siping in the tread blocks. Large, smooth tread blocks may hook great in the mud, but they won't be ideal on slick, icy surfaces in winter.

As for the rear bumper, it's possible to fabricate nearly anything if you have the skills and correct tools. If you go this route, you'll want to attach the swing-out spare tire mount directly to the frame horns with sturdy brackets. The spare tire and wheel are pretty heavy and will tear up the factory bumper, so you can't attach it there. The other option is to check out a heavy-duty bolt-on bumper with a swing-out tire carrier from a company like Proto Fab (protofab4x4.com). The Proto Fab Rock Solid rear Bronco bumper is available with or without a swing-out tire carrier and gas can holder. The company also offers the rear bumper in a kit that you can weld together yourself.

 

Cranky Sensor
Can you explain the importance of a crankshaft position sensor and exactly what happens when one goes bad? I just replaced one on my '06 Jeep TJ Wrangler. It was a horrible affliction on the highway anytime my Jeep got over 60 mph. It felt like I was getting jerked backwards anytime I got up to any real speed. It kept me off the interstate for almost a year. It was also misdiagnosed by a couple mechanics before one nailed it.
Cory Murphy
Via facebook.com/JohnCappa4x4

A failing or broken crankshaft position sensor can cause all kinds of drama. The crankshaft position sensor basically lets the engine computer know the position of the crankshaft. It ultimately helps the engine computer manage fuel and ignition timing. If the sensor isn't working properly, the engine computer has no idea where the pistons are in relation to top dead center. The computer won't know when to squirt fuel through the injectors or spark the ignition. A completely broken sensor typically results in a non-start situation. A failing sensor may allow the engine to still run—but poorly. Functionally, you can compare a failing crankshaft position sensor to dropping the distributor of an older engine in the incorrect position. You might get it to run, but it will never run right. The good news is that the 4.0L engine in your Jeep is nearly bulletproof, so if it does act up, it's usually a sensor or electronic part, such as the crankshaft position sensor or something fuel related.

 

Death Wobble Dilemma
I have the famous death wobble question. I drive a '12 Jeep JK Unlimited with 4 inches of lift rolling on 35-inch tires. I've changed my steering assembly and ball joints. I'm still getting the wobble at times. Could the control arms be another component to look at? If I have to change them, would a three-link suspension be a better option?
Ronnie Longoria
Via facebook.com/JohnCappa4x4

There are many things that can contribute to the violent, uncontrollable shaking of the front tires, also known as death wobble. Generally, death wobble is not caused by just one thing, but rather a combination of slightly worn or damaged components that can create too much slop or an undesirable condition in the steering and suspension. To answer your question: Yes, worn control arm bushings can be part of the cause of death wobble. Unfortunately, simply switching to a three-link suspension won't necessarily make your Jeep less prone to death wobble. In fact, a four-link suspension with a track bar, such as what comes on the Jeep JK from the factory, is the best solid-axle suspension design for maintaining axle alignment and proper handling. Worn or loose track bar mounts and/or worn drag link ends are the most common cause of death wobble.

Other things to check include tire balance, all suspension and steering joints and mounting points, steering ball joints, pitman arm, and so on. Carefully inspect all of the suspension and steering mounting point holes. If any are wallowed out, they will need to be repaired or the component will need to be replaced. You'll want to optimize the tire pressure to make sure the tires are not crowned and chasing grooves in the road. Also, check the toe-in and caster. A bent front axlehousing can accentuate a death wobble problem. There are some applications where all-new components and corrections won't solve a death wobble problem. In some of these extreme cases a steering stabilizer will be required to keep death wobble at bay. However, don't try to use a steering stabilizer to mask the worn or damaged components under your 4x4. The steering stabilizer should be the last resort once every other steering and suspension component is in good operational condition.

 

YJ Exhaust Leak
I have a '87 Jeep YJ Wrangler with a 4.2L inline-six engine. I replaced the cracked exhaust manifold with an aftermarket manifold. Now, two months later the intake and exhaust bolts have worked loose due to the metal expanding and contracting. I have heard this is a common problem. Is there anything to be done other than having to tighten the bolts again and again?
Richard Drechsel
Via facebook.com/JohnCappa4x4

Unfortunately, exhaust manifold gaskets and bolts often need to seat, especially on the longer inline-six engines like your 4.2L. You may need to retighten the hardware several times before the exhaust is completely seated. Use a torque wrench and tighten each bolt to spec in the appropriate pattern, which is generally from the inner bolts outward. In some cases, the cast-iron exhaust manifold will warp and never seal properly. The Jeep inline-six engines are notorious for having warped exhaust manifolds. In these applications, a high-quality aftermarket header is sometimes less prone to warping than the cast-iron exhaust manifold. Companies such as PaceSetter Exhaust Systems (pacesetterexhaust.com) offer a header for the Jeep YJ 4.2L. If you decide on going with a header, steer into a ceramic-coated version if you live in a wet state or regularly hit mudholes. The ceramic coating will help keep the header from corroding.

 

Flipping Leaf
I read your recent tech column and had thoughts on the advice you gave about swapping ends on leaf springs. The entry was titled "Easy Wheelbase Extension." Depending on the leaf springs, they may have a double wrap at the frame end (not the shackle end) of the spring. If this were the case, turning the spring around may not be possible and may even be dangerous. I do love reading your tech advice, and would not presume to tell you how to advise one of your readers, but when discussing matters of safety, I can seldom keep my mouth shut.
Matt Stoffregen
Stoffregen Motorsports

Good point! Not all leaf springs are good candidates for flipping. Some even have different-size hardware and bushing diameters and widths, making the spring flip swap even more difficult. Regardless of the recommendations made here, you should always keep safety at the forefront when making modifications. If it looks or feels sketchy, it probably is—so don't do it.

 

2x4 Grand
I need your help. I bought a two-wheel-drive '99 Jeep Grand Cherokee Laredo. I want to make it four-wheel drive. Can you help me? Is it possible?
Kevinkumarace Doekhi
Via facebook.com/fourwheelermag

Your desire for a four-wheel-drive Jeep is totally understandable. The good news is that most two-wheel-drive SUVs can be converted to four-wheel drive. The bad news is that the amount of custom fabrication varies depending on the vehicle make and model. Fortunately, the two-wheel-drive '99-'04 Jeep Grand Cherokee is one of the easiest vehicles to convert into a 4x4. Both the 2x4 and 4x4 versions of the WJ Grand Cherokee feature a solid front axle. The two-wheel-drive Grand simply has an empty solid beam front axle where the 4x4 has a real live axle. These front axles are completely interchangeable. The '99-'04 4x4 Grand Cherokee front axle will bolt right to the stock suspension mounting points and components under your two-wheel-drive Grand. The brakes and knuckles are nearly identical, so they are completely interchangeable too. All of your steering linkages will also bolt up. Ideally, you can get your hands on a complete '99-'04 WJ Dana 30 front axle assembly and simply slap it in. If the new-to-you front axle has the same gear ratio as the rear axle in your Jeep and is in good condition and ready to run, this swap could be performed in a few hours using simple handtools. Having to alter the gear ratio of your new axle will add a lot of cost and complexity to your swap.

To complete your 4x4 conversion, you'll need to convert to a 4x4 version of your transmission and get your hands on a transfer case, shift linkage, and the front and rear driveshafts. You'll also likely want to figure out the wiring so that the 4x4 lights in the dash function as designed.

If you're starting to think this sounds like a lot of work and expense, you are right. Unfortunately, it's really not a cost-effective swap, unless you already have all the parts lying around and can do the work yourself. Even then, it still makes much more sense to simply start with the Jeep you want. It's not difficult to find a good used 4x4 '99-'04 Jeep Grand Cherokee. In most cases, it will cost you more money to convert your 2x4 Grand to a 4x4 than it would cost to simply sell your Jeep and buy a 4x4 WJ.

 

Steering Shafted
I have a '72 CJ-5. I bought it with Vietnam tour money. We recently changed it to power steering, which works great, but now I do not need the steering shaft to be as long. Does anyone make a shortened steering shaft? The Jeep has the original AMC 304ci V-8 engine and is lifted 2 inches but handles like original. We did a frame-off rebuild in 1991.
Dan
Via email

It's awesome to hear that your Jeep has stuck around so long. Converting to power steering is a great upgrade, especially when considering larger tires and lower air pressures for trail use. Direct bolt-in steering shafts are available for your Jeep from companies like Borgeson (borgeson.com) and Flaming River (flamingriver.com). These companies also offer steering shaft parts if you need to fabricate your own steering shaft that has to snake around an exhaust or other component.

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