We'll grant you, lifting an IFS truck generally requires more time and expense than lifting an older solid-axle rig, and there are limits with an independent suspension on how high you can realistically go if you need any suspension movement. On the other hand, you don't really need to lift an IFS rig so much since one inherent virtue of its design is the way it relocates the front diff upward to increase ground clearance. To get the same benEFIt in a solid axle, you'd need to swap in Euro-style portals, which are not easy to find, and far from inexpensive. And IFS technology only continues to get better-witness the new generation of OE adjustable airbag and/or electrohydraulic setups such as those found on the newest Land Cruisers and Land Rovers, which can compensate for IFS's shortcomings in travel. And if you don't think these new technologies won't eventually trickle down to the average-guy aftermarket, just wait-20 years ago, they said the same thing about multilinks on monster trucks.
We'll also concede that some of the earliest "inferior" front suspension kits had reputations for poor reliability. But nowadays, quality aftermarket IFS setups feature aircraft-grade componentry machined out of CNC billet and other space-age goodies, so toughness is no longer an issue. That's why Baja racers have run independent setups for years, and there's no one else on the planet who's tougher on suspension parts than those guys.
Of course, if you need a vehicle with huuuuge flex (e.g., rock buggies), or you've simply got to have 49-inch tires with that 18-inch spring lift (old-school boggers on a budget), OK, a solid axle is really your only option. But for the other 90 percent of us who need our rigs to Do It All, and do it elegantly, an independent suspension is the way to go.
-Douglas McColloch
Project 'Con Artist shows the articulation potential of a well-engineered solid-axle suspe
Solid Ability
The future of new vehicles is all about IFS, which does have advantages over solid axles, such as lower unsprung weight, better ride, handling, and high-speed stability. However, when it comes to real wheeling, solid axles hold a superior position over IFS.
With a solid axle, you have the inherent benEFIt of constant traction in the design. As long as there is enough suspension travel to compensate for the terrain, a solid-axled vehicle is more likely to have all four wheels touching the ground because as one side is forced up by the terrain, the other is forced down in contact on the opposite side, unlike IFS which often hangs a wheel in the air, relying on traction control or a traction aid to keep the other wheel in contact with the ground moving.
Solid axles also keep more weight toward the bottom of a vehicle, for a lower center of gravity, helping keep the rig upright in extreme situations. They are stronger and more rugged, with cast-iron housings that can take trail abuse and handle lockers and shock loads better than the lightweight aluminum housings found in most IFS rigs. Solid axles also maintain the same ground clearance over obstacles, while IFS has variable ground clearance as the suspension goes through its cycle, raising and lowering the front subframe. And solid-axle setups often have stronger steering systems and aren't susceptible to extreme camber and toe changes under load and cycle as an IFS rig is.
Other advantages to a solid axle include a simpler design, with less moving parts that are easier to service without any subframes in the way. And when it comes to suspension modifications, such as lifts, it is far easier and more affordable to lift the solid-axled vehicle. Solid axles are also more cost effective and easier to beef up, whereas the IFS strength is built in to the design and is not easily upgradeable. The bottom line is that solid axles are affordable and plentiful, and there just isn't an affordable IFS system that will match the strength and reliability of a comparable solid axle.
While it is true that IFS has its place and can be designed to work quite well, you don't often hear of IFS swaps. I rest my case.
-Sean P. Holman