As you certainly have noticed, with the recent presentation and reviews of the LEGO Technic 8110 Unimog U400, some questions have raised regarding the small offset on its front suspension.
Here we have the official explanation on how and why it was done this way.
There is a geometrical reason for this, the front axle is stabilized by a Panhard rod, the panhard rod is there to prevent the entire front axle from moving from side to side. The shock absorbers would simply be too flexible to support the front axle on their own.
When the suspension is fully compressed, the front axle needs to be centered right underneath the vehicle in order to prevent the wheels from hitting the chassis and wheels arches, when turning.
That means when the suspension is fully extended the panhard rod will make a “circular” moment that pushes the front axle slightly to the right of the vehicle.
In the real world, these geometries are balanced out by fine tuning the length the panhard rod.
So if your front axle is offset by half a module, you have built your new LEGO Technic U400 Unimog the right way.
Have a nice summer and stay creative.
In fact I've noticed the Panhard rod explanation from Wikipedia which says,
"The advantage of the Panhard rod is its simplicity. Its major disadvantage is that the axle must necessarily move in an arc relative to the body, with the radius equal to the length of the Panhard rod. If the rod is too short, there will be excessive sideways movement between the axle and the body at the ends of the spring travel. Therefore, the Panhard rod is less desirable on smaller cars than larger ones. A suspension design that is similar but dramatically reduces the sideways component of the axle's vertical travel is Watt's linkage.
Some vehicles including Land Rovers with live axle suspensions use a Panhard rod as a component of the front suspension where Watt's linkage is not an option."
The Panhard rod has the advantages of lighter weight and less complexity. A Panhard should be as long as possible to minimize lateral displacement as the bar swings through its arc. The bar should also be level for the same reason.
What was not realized was the fact that the alignment is more important when the suspension gets fully compressed, to prevent the wheels from hitting the chassis and wheel arcs (specially when steered), than when it is fully extended. Thus we observe the misalignment most of the time, when the model stays at rest.
On the video below you will see the lateral displacement of the chassis, relative to the front axle.
Pay attention to the dark tan studs or the black tow balls. When the suspension is fully compressed it becomes perfectly centered. It displaces again up to one half module, as the suspension gets fully extended.
The equivalent situation is not as relevant for the rear axle, because it does not steer. So by design, it keeps aligned with the chassis when the suspension stays on its normal position (fully extended).
Thanks Ricco, for your enlightening explanation!