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Is A Solid Axle Right For You? - 4-Wheel & Off-Road Magazine

Fred Williams Brand Manager, Petersen’s 4Wheel & Off Road

Luddites were English textile workers who opposed technology because it reduced labor. As a form of protest they burnt down factories. Often the term Luddite is applied to anyone standing in the way of the progress and evolution of technology. We may be Luddites, but we’re here to say we still like solid axles, and don’t think we will stop burning some metal as we cut out IFS and weld in a solid front axle. Even though we are now down to just three new vehicle models available with a solid front axle in the U.S.—Jeep Wrangler, Ford Super Duty, and Ram heavy-duty trucks (four if you count the über-expensive Mercedes G-class)—we’re still huge proponents of the driven beam axle construction for off-road use.

ifs Axles And Swaps chevy Blazer And S 10 Photo 40503321

But hold on a second. If every manufacturer is offering an independent front suspension (IFS) in its 4x4s and some are even offering an independent rear suspension (IRS), then are we just being ignorant cavemen by still cheering on our heavy, strong, rock-simple solid axles? We admit we have serious respect for IFS and IRS, as can be seen by the Ultimate F-150 we built last year and the Land Rover LR4 that won our previous year’s 4x4 of the Year contest. Both are fitted with IFS, and the Land Rover is also fitted with IRS.

So where does this leave you, dear reader? The options for a 4x4 trail rig platform with IFS far outnumber the solid-axle vehicles, but the aftermarket support for serious off-road use and abuse is stacked in the corner of solid-axle vehicles (mostly behind the Jeep Wrangler). If you have an IFS 4x4, are you out of luck? Are you destined to chop, grind, and weld a big chunk of steel where your wishy-washy A-arms or twin traction beams used to live? Or are the winds of change blowing and the heavy caveman clubs of Dana 44s, 60s and all the other massive unsprung axle weights destined to be buried by the sands of time?

ifs Axles And Swaps ford Raptor Front Suspension Photo 36879652 Every new small-body and 1⁄2-ton 4x4 truck and most SUVs currently sold have independent front suspension (IFS), meaning their front wheels move independently of each other. IFS has the benefit of less unsprung weight and, in turns, improved ride quality over a solid front axle. IFS is commonly assembled with two A-arms and a knuckle per side, though twin-traction beam is an IFS suspension found on some older Ford vehicles. Torsion bars, coils, or most commonly coilover shocks are the spring of choice on IFS vehicles.

Spoiler alert! There is no right answer, but read this before you spark that torch or order those long-travel A-arms.

PhotosView Slideshow Most older 4x4s (pre-’80s) and a few newer 4x4s have a solid front axle. The solid front axle is considered robust, having fewer moving parts to wear out, simpler steering and, when using leaf springs, a very uncomplicated suspension. However the solid front axle can be very heavy, and this can reduce ride quality at high speed. A solid front axle can have a variety of suspension designs (leaf springs that locate and suspend the vehicle were very common), but all newer solid-axle 4x4s have link or radius arms with coil springs. If you currently own an IFS 4x4, you may be considering your options for keeping the IFS or swapping in a solid front axle. Generally, stock IFS components are strong enough for tires up to the 35- to 37-inch range. This depends on how you drive, where you drive, and how much power and gearing you are using. Logically, a smaller IFS truck will have smaller parts than a 3⁄4- or 1-ton IFS truck, so smaller tires should be considered. If your four-wheeling includes gentle mountain exploring, easy to moderate rockcrawling and trail riding, or high-speed off-roading, then IFS is perfect for you. Keeping the tires size to a minimum (35 inches or less) is important, and we would be cautious of a front locking differential if your IFS front gear housing is aluminum. If your goal is to keep your 4x4 as low as possible for a better center of gravity, then keeping IFS may be your best option. The axle centersection is often mounted tight up against the engine, where a solid front axle requires space for the axle to move upward during suspension compression, in effect raising the overall height of the truck. Keeping the vehicle low with smaller tires can also result in better fuel economy versus a lifted truck pushing bigger tires with worse aerodynamics. There are more and more long-travel IFS suspensions available for 4x4s. These incorporate longer A-arms to widen the front track, requiring longer halfshafts and steering links. By pushing the knuckles out farther from the frame, they go through a larger arc and increase travel from full compression to full droop. Long-travel suspensions rarely offer as much tire size increase as a lift kit would, but are designed for greater off-road performance, especially at speed. There are options for IFS with big tires, such as the suspension we put under the Ultimate Adventure F-150, but these are expensive and only currently becoming mainstream. Dynatrac built a custom ProRock 60 centersection, RCV supplied massive axleshafts, and Randy Ellis Design built A-arms and knuckles with Fox coilover shocks. One benefit of an IFS, especially a custom IFS like this, is improved ground clearance under the differential compared to a solid front axle. Expect a front end like this to cost as much or more than a solid-axle conversion until parts become more available. If you are considering a solid-axle conversion then you need to consider what axle you will be installing. Toyota solid front axles are popular, as are Dana axles. We would not suggest a Dana 30 in a large truck because it is very small, unless you were willing to upgrade the 30 significantly. A Dana 44, GM 10-bolt, or Toyota solid front axle can all be built to survive up to 37-inch-tall tires with moderate control from the driver and a lower-horsepower engine. As you move up to rubber bigger than 37 inches, V-8 power, and abusive driving, you are in the market for a 1-ton front axle such as a Dana 60. Though overkill for many off-roaders, the Dana 60 has become the Holy Grail for many and can be built from junkyard parts or by many of the boutique axle builders in the aftermarket, such as Currie and Dynatrac. Dana 60s are good up to a 42- to 44-inch tire, again with respect to power and abuse. The Ford 9-inch is also available as a solid front axle with custom fabricated front housings, such as this one from Spidertrax. High- and low-pinion third members, as well as various gear ratios and lockers, are available. We would consider a front 9-inch up to a 40-inch tire because we find their lighter weight appealing over a Dana 60 for a go-fast, solid-axle 4x4. By the time you are looking at 44 or larger ruber it’s time to consider serious axle upgrades in the custom 14-bolt, portal, or 21⁄2-ton front axle varieties. Most likely you’ll be custom-fabricating a suspension for these axles and your 4x4 will be towed more than driven to the trail. Steering is another huge consideration when devising a solid axle recipe. If your 4x4 has rack-and-pinion steering you’ll want to upgrade to some sort of steering box for street use, and the best box will be determined by the suspension design and axle location you choose. Full hydraulic steering isn’t bad for a dedicated off-road vehicle, but experience tells us it’s not really suited for a street machine, though it can be much easier to install than a steering box and drag link. If cost is a consideration (it usually is) then you need to seriously determine where you are headed with your 4x4 before you consider a solid-axle swap. They can be done at home with junkyard parts on a budget, but often a simple lift or leveling kit will suffice for slightly larger tires on the IFS 4x4 that isn’t destined for rough use off-road. We know many people who four-wheel quite aggressive trails worldwide with IFS, and though they can experience alignment issues and odd tire wear, these are not unheard of with solid axles either. There are tradeoffs with solid-axle suspensions or IFS; you just need to determine the lesser of two evils for yourself.

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