Mark, I'm not booing the band, You have asked the same question a hundred others have; 'I want XYZ but I dont want 'hassle' and I want it on the cheap', and unfortnately, there ent no thing as a free lunch. And I DO know what I'm talking about, I'm afraid.
Doesn't matter whether you have leaf-springs, coils or deuche bags between your chassis and axle, same problems occur. Stretch air-bags to get a lift, bung in longer coils, or stick on bits of scaffold pole to push them further apart, same things happen.
First; moving chassis further away from floor raised the centre of gravity.
On what is such a tall vehicle to begin with, 2" on best part of six foot, might not seem significant, EXCEPT, Landies carry thier weight low, but its nearly all above the axle centres, so the actual 'shift' in centre is more marked than % lift would suggest. Worse on a Disco, as unfortunately that model is already one of the more top heavy, AND has a high 'roll-centre' due to the higher roof-line and unitary construction steel shell on top of the chassis, it has a 'dumbell' moment of inertia, with so much weight in the roof, so lifting it 2" gives you a double whammy on the stability front.
NEXT: moving axles away from chassis, rotates the axles in relation to the chassis; the diffs no longer point at the gearbox, and the steering axis no longer has the same castor angle.
With the prop angles changes, tendancy is for the UJ's to wear excessively, through transmitting drive through too acute an angle; not being CV joints, the mismatch in flange angles creates drive line vibration, that again, prematurely wears UJ's, and THAT is if they dont actually start to 'bind' as increased travel sees them forced to flex to an angle beyond thier limit.
Meanwhile; at the front, leading 'link' radius arm arrangement, has twisted the axle forewards, making the steering angle a lot steeper. This makes the steering very 'nervouse' and less inclined to 'self centre'.
On a 2" lift, the amount of 'rake' removed from the steering axis is close to reducing the castor to zero, near the new nominal ride height, and loading or suspension movement can see the castor angle go negative, the steering axis falling behind the tyres contact patch, and behaving like a wobbly supermarket trolly.
Carrying on........
Landrovers have 'long travel suspension', they also have old fasioned recirculating ball and drag-link steering, to waggle the wheels over that range of suspension travel; and in consequence suffer a phenomin known as 'bump-steer' and 'roll-steer' where, as the distance betwen axle and chassis changes, or as the angle of the axle in relation to the chassis changes, so the geometry and effective angle and length of the drag link changes, causing 'undesireable steering effect'
In short, as the thing 'rolls' into a corner, the body rolls trys changing the angle the front wheels are pointing.... when you strike a bump, changes the angle the wheels are pointing.
Lift your landy, and you change the steering geometry, and may need to get the steering re-tracked and re-centred at the new nominal ride height, but THEN, over the wider range of travel, the thing will 'wobble' more from the greater movement between axle and chassis, and it will be particularly acute during cornering, where the raised centre of gravity, and the even more greately increased roll centre compound to give greater body roll, hence greater roll steer, over the greater amount of suspension travel you have given it.......
Do I need to continue?
Like I said, if you know what you are doing, go for it. But HOWEVER you lift a landy, the 'consequential' problems are numerouse, and yes, many 'live' with them...... but as you have explained your Disco is an all-round Family Waggon, I'd NOT be too keen to turn it into an 'extreme' off-roader whose on-road dynamics are such it handles like a blemange, and was likely to do an SJ 'flip' in an emergency brake steer situation....
If you WANT to do, it, then I'm afraid its NOT something to be done on the 'cheap'. First off, longer air-bags, with the extra travel you want, AND a diameter that means they give that extra travel without higher pressure making them harder, so you dont 'get' that extra travel; Then, longer dampers and revised damper mounts to accomodate the extra travel without them topping out, bottoming out or fouling; Then, camber corrected radius arms to bring the steering geomtery back into line, and 'extreme angle, double cordon prop-shafts, to stop them shaking themselves to bits in too much of a hurry, or binding; And with that lot sorted, you can play with the ride height sensors; BUT you'll still have something that is 2" higher and handles like a blemange, and getting the ride height back down, for road use, will mean lower pressure in the sacs, so squdgier suspension, and more roll when you drop it... but not as much and not over quite so much suspsension movement.... oh, and the steering wheel will possibly be a bit off centre when you drop it....
And back to the original suggestion; what 'gain' do you expect for it all? Even if you do it the expensive way? Bellying out, and extra 2" is NOT going to make that much difference, and if you are resorting to winching, well, it will probably just mean that you get 2" further into trouble before you have to crack out the waffles and leader line.
Back to reading the terrain and NOT trying to take your vehicle places it WONT go. If you want to drive into those places, and follow expensively kitted Toyotas, leave the Dizzy at home, and get an expensively kitted Toyota..... or try a Defender.
Modified vehicles are rarely 'better' than the standard model; the mod simply increases 'capability' on one area of its perforance in sacrifice for another; and more often than not, ameteur mods often lose more than they gain, and cost a lot to get it.... like I said, theres no such thing as a free lunch, and rarely an 'easy' fix.
