In addition to hate mail I have received numerous well written emails, mostly from the off roading crowd to explain to me the virtues of what I see as ancient on-road technology. I am publishing some of these to give the reader a different perspective to what I have written, which is looking at things from a grocery shopping point of view.
Very usefull, and correct, information here. :) However, you missed the ball with the live axle VS Independant suspension. The Hummer, beleive it or not, has a rather weak suspension. (Sit around on a difficult trail, and chances are, You'll see a hummer break it's suspension.) The Military people I associate with agree with me on this, but a Heavy- HEAVY duty suspension is not was they were aiming for, they wanted something that can move through *MUD*, and LOTS OF IT. (and keep vital components away from land mines). the Hummer's unique independant suspension system is very good at this, but if you look at all of the other independant systems out there, they simply are not up to the task of any moderate to difficult off- road usage. Live axle's *ARE* much stronger than the current style of independant suspension. There is a new breed of suspension currently under developement by some of the major 4x4 makers which I dub "Cross axle", combining the best of both worlds; basically the right wheel's axle goes all the way across to the left hand side, and vice versa. This provides for the strength of a solid axle, as well as *MONSTER* articulation and handling at any speed in any terain. (see below for Articulation) Second part you missed about Live axle vs Independant, is wheel articulation. Live Axle vehicles with coil spring suspensions get *MUCH* better wheel articulation than Independant vehicles. Of course, almost all 4x4's come with anti-sway bars to limit articulation for on-road driving, but most avid "Off-roaders" remove these to get the max articulation out of their vehicle. (Articulation is Wheel travel, BTW, the distance the wheels can go up and down. the better the articulation, the more those wheels can travel, and the more the wheels can travel, the better, since you can keep all four wheels firmly planted on Terra Firma, thus maximizing traction and stability (and reduce wear and tear on suspension components and the frame). [...] In theory, Indendant could do alot better than live axle. However, the ride would be so bone-jarring that not even us 4x4 off-road nuts would want a setup like that. :) The Current independant setups are more geared towards having a smoother ride, which is what the majority of "SUV" buyers want. :P (I *REALLY* don't get IFS setups, where only the front is independant, the worst of both worlds. You don't get any extra ground clearence from the differential (due to the remaining rear axle) and you don't get decent articulation. And, nobody *BUT* AM General has designed their Independant suspension setups to be remotely strong enough. (If you can show me another current independant suspension vehicle that's at least as strong as the Hummer, Please do!). There have been arguments about Live axle being specifically better for articulation than independant suspension for one of the reasons you give in your report: When one wheel hits a bump, the other reacts. It also works like this: When one wheel goes up, the other is forced down, whereas in many Independant setups (Hummer included) when one wheel goes up, the other just sorta hangs around. :) Oh, I just got a nudge over here from someone who's been doing this alot longer than I have (since '67), he also wants to point out about Compression: On a live axle, when you hit the ground, both wheels go up (obviously) to absorb the shocks. This is OK, because the live axle carries the differential up with it. on an Independant vehicle, when the Wheels go up, the Differential goes down. So when you need ground clearence the most (on "Landings") on some vehicles It's possible to get the differential *LOWER* than the bottom of the tires!!! And on most others (Hummer being the only exception he knows of), the Differential still drops dangerously close to the ground, close to rocks, stumps, ETC that the 4x4 owner is trying desperately to avoid. We've both seen IFS vehicles rip out their front differential this way. Of course, we're insane, We do things like heavy-off-road driving, whereas the average SUV owner never sees a Dirt road. :) [..] PS, a sidenote to Full Floating solid axles: It is alot harder to break a solid axle, and as an added bonus, a full floating solid axle can break and *STILL* be usefull. Should the axle itself break, the axle housing will still remain, as a support for the wheels, even though the axle might not give power to the wheels, at least it is still drivable by the other axle. (Independant suspension, if something breaks, well, heh.) Live axles are also much easier to fix out in the field, Many of the people I go off- roading with up here carry underhood welding systems, they can simply weld an axle back together should it break. Fixing an independant system in the field is also possible, but much, much trickier. This is one of the reasons people in the outback like Australia, Africa, (even some of the less accessable areas in north america) greatly prefer live axles. (of course, many SUV's of today use Semi-floating axles, which lose some of the bonuses of Full Floating axles, but still are sturdier and easier to fix than independant systems.)
your article was valid (and funny) but i will have to kind of disagree with you on one point. 4 wheel independent suspension is more _comfortable_ on road as well as off when compared to a live axle suspension. However, live axles do have 2 big advantages to us that use our off road vehicles as off road vehicles. (I despise SUV weenies also) Those benefits are: 1) Strength. Live axles are stronger than independent suspension setups because of their simplicity. Granted, the Hummer's axles are probably stronger than my Jeep's axles, but they are made of much higher strength material. I could point out several examples of where an independent suspension would just not cut it in a "real world" application. (dump trucks, trailer trucks...) 2) Off road prowess. You mention that most off road race trucks have independent suspension, but that is a similar application to road handling. At high speeds, independent suspension handles the small (and large) bumps better than a live axle setup. However, when the speed is slow and there are bumps (rocks, stumps, etc.) that are as large as your tires, it is important to keep all four tires on the ground for traction. With independent suspension, what happens to one tire does not affect what happens to the other tire, thus, when the tires get "crossed up" (right front and left rear on seperate rocks)there is more of a chance that you will have one or two tires off the ground. The live axle design handles this problem better. As you already know, the average person buying a SUV does not encounter either of these situations, so your arguements stand.