Rear right suspension travel
When I was replacing my rear springs a month or so ago. I found that removing the left strut would allow that side of the axle to drop quite a distance and the spring could just be easily removed. When I removed the righthand strut it did not drop really at all. It lowered enough that the spring could be wriggled around a bit by hand, but not enough to remove without spring clamping it.
I didnt really look into what was stopping it from dropping any lower, but it did get me thinking. If someone was to put in longer struts/springs, wouldnt whatever is stopping this side from dropping remove any extra travel you should get, on the right hand side anyway?
You got it!
Last night I took a peek under my iO, and noted that the panhard rod connects to the axle on the right - I was tempted to post, but didn't because I'd already suggested it.
Yup, you got it, i've compressed one side while driving to the point of having the tyre jam in the rear arch, when I checked the panhard bush was worn out. As I was changing it I noticed the rear would drop further with it disconnected.
Easy.
The panhard rod (also called a track bar) provides lateral (or sideways) location to the axle - it's a rod that runs horizontally from one side of the vehicle to the other, with one end fastened to the axle, and the other to the frame.
The Pajero iO uses what would be termed a 5 link rear suspension - there are two sets of radius links on each side of the vehicle that locate the axle 'fore & aft', allowing it to move up & down - but - it can also move sideways unless there is something to prevent that movement - which is where the panhard rod comes in.
Ideally the panhard rod should be horizontal with the vehicle in an "unloaded" condiiton - on lifted vehicles the panhard rod will be at an angle unless one of the mounts is extended to compensate for the lift, and this causes the axle to be "dislocated" sideways - you can correct the dislocation by extending the panhard rod itself, but this is not the best way to do it
You may also see this suspension design called a 4 link plus panhard rod.
Syndicate
uhhh - food for thought.
It might depend on where you were supporting what.
I'm going to guess that you had the body on jack stands and possibly the axle on a jack so that you could lower it - if I assume that jack was under the differential and you did one side at time, left side first, then the longer spring on the left will limit how far up the left end of the axle will travel and with the axle pivoting on the jack under the differential, that limits how far down the right side can go.
In a real world situation that jack would not be there.
The other possibility is the panhard rod or dependng on the particular vehicle, it may have been fitted with a rear anti-sway bar - later models have them, the early ones don't.
Anti-sway bars do limit articulation, and the panhard rod, which locates the axles side to side can limit up & down movement if you restrict the sideways movement of either the body or the axle as may have happened with either one or the other on jack stands or a jack.