Good write-up, Brendan.
I’m gonna expand on some of my previous ravings re: wider track v lift restrictions, etc.
First, lift restrictions.
While most of us can’t understand why 50mm is the current max, there are reasons why I think the authorities have decided on this figure. One of the test parameters for this is that the vehicle test dynamics are based around the vehicle being loaded to its maximum carrying capacity. In this condition, it reacts much more to lateral loads (ie swerving, off camber and angles associated with off road activities, etc.) and therefore, more likely to roll over. Even allowing the max track increase of 50mm, the stability of the vehicle is pushed to the limits. The way the vehicle is loaded is also important to these tests, as a heavy mass low on the chassis (a load of bricks, for example) will be more stable than a higher more bulky mass (a large piece of machinery). So, to allow for some of these variables, a maximum height is calculated to keep the vehicle upright based on the wheelbase, track width and height. These factors are easily calculated with modern software, but actual testing is needed to make sure that these calculations are correct. My motorsport experience tells me that widening the track (wheels, suspension alignment, etc.) and lowering the vehicle make it more stable and handle better by keeping the car mass as low as possible.
Diff lowering (Triton).
Lowering the front diff in the Triton is a waste of time. Period. While it MIGHT allow a slightly longer CV life, it throws other problems into the mix. I’ve spent a few hours under mine with the covers off and taken dozens of measurements and pictures to help with my goal, only to realise that it’s a worthless exercise. The loss of ground clearance cannot be made up in a lift inside the lawful parameters. The rear X member must be lowered to allow the nose of the diff to come down, and lowering the casing puts the fragile front cover closer to damaging rocks etc, which means lower skid plates, less GC and defeats the purpose of the lift. On American trucks and big lifts, the diff MUST be lowered with the lower arm mounting points to keep everything in alignment, as the knuckle is longer at the top to allow the drop of the main suspension pieces. On the Triton, we are just moving the axle shaft lower at the inner end with possible interference with the lower arm at full droop. Without dropping the lower A arm mounting points at the same time, it’s just not practical. A waste of time and money, in my opinion.
Now, here comes the track width increase.
Here is my theory:
Imagine a triangle. The base of the triangle is the ground. The length of the base is the track width (1600mm for reference) and the height of the point is the centre of gravity of the vehicle (800mm). When the vehicle is lifted (lets say 100mm for reference sake) the triangle is higher with a narrow height to width ratio (less than 2:1), and easier to tip over, with me so far?
Now, we take the triangle with 1600 x 800 and make the base wider (125mm, my intended track increase from my kit idea) and look at our triangle now. We have a shape that is much harder to tip over, due to the much better height to width ratio (better than 2:1 @ 1725 x 800, 2.156:1 to be exact). In real life, this is a HUGE difference in stability, hence the reason the Chapmans have increased the track on the Pajero and Triton so much. It’s all about wheel travel AND stability over rough ground. Still with me?
Now, we take the track increase and lift the COG 70mm (my projected height increase and come up with 1725 x 870 (1.982:1). That’s less than 2% different from factory, and well within the MN’s ESC capabilities. Add a 17” rim and tyre package to this and the math is even closer. I put this to my Engineer in a long email on Friday last week and the reply back is VERY favourable. He will consult with some other engineers on this and get back to me, but in his words, the math puts the track increase based on my theory in a good position for approval, and with FEA to back it up, I could get the green light for prototyping. The rear axle will need to be widened a like amount (120mm) but I plan on using a Currie Track 9 with Triton ends and possibly Pajero discs grafted on, or even Wilwood’s offerings to get rid of those useless drums. Anyway, that’s my input, feel free to flame away.