Thanks for the helpful reply. It's very useful speaking to experienced land rover experts.
So, I'm a big believer in the benefits of high flex for off road. Both in terms of improved traction and off road comfort. I also think long travel 4x4s without anti roll bars are just more enjoyable off road. I dislike driving stiff modern IFS vehicles with lots of traction control.
So with the disco 2 that I recently acquired, my intention is to do everything I can to maximise chassis performance. This means retaining road handling best I can whilst substantially gaining off-road. Other off road aids may come down the road such as locking diffs but its the character of the chassis I most want to change.
I realise this sounds like conflicting goals, but as an engineer this makes it interesting! I expect the modifications to be fairly extensive/extreme and possibly unconventional.
Although I am new to Land Rovers, here's my semi-informed requirements/brief:
1. Maximise the droop travel. (long travel dampers, dislocation cones or two stage x-spring)
2. Keep ride height low as possible for stability (minimum lift possible for tyres).
3. Maximise torsional compliance/flex (minimal or disconnect anti roll bar).
4. Avoid significantly compromising on-road handling (maintain near stock spring rates, ride heights and anti roll bar stiffness).
5. Retain and utilise existing ACE.
Here is some initial thoughts on parts:
plus 5" terrafirma dampers
View attachment 321026
x-springs
View attachment 321027
Anti roll bar disconnect front only:
View attachment 321028
Looks interesting.
As said, I’m not an expert or owner of a D2. However I would probably start at looking at longer shocks.
I’m pretty certain you’ll see some gains here. On a Defender/D1 you can go +2” and not worry about too much else.
If you want to go +5” then generally you need to move the upper shock mount. I’d assume this is true in the D2. But don’t know what options are available.
This is because the closed shock length will be longer and the shock will be fully compressed before you hit the bump stop.
Now to some extent you can just keep moving the travel further away from the chassis and use extended bump stops. But you tend to end up with a huge lift. Which can promote stability issues, flex issues and other geometry issues that mean most of your travel is droop and not compression. So off road you end up riding the bump stops and lifting wheels more easily than a less flexy setup.
Now I’m not against lifting. And with the long wheel base of the D2 and relatively poor approach and terrible departure angles. A lift can really help. Other issues with large lifts are poor propshaft angles that make the props more prone to breaking. Diff pinion angles and poor caster.
It really is quite a balancing trick to keep all bits working well and not too compromised.
A +2” shock might not sound much. But will give quite a lot more flex.
Remember to add longer brake lines!!!!
If you do get lots of flex you may still get prop binding which can also break propshafts. So you’ll need to consider wide angle props too.
In terms of springs. I’m guessing your are coil all round on not air on the rear?
I personally like softer springs as they will flex more. More will offer less carrying load on road and may not suit road driving as well. Again a balancing trick.
As said, I typically like not to lift too much. One of my vehicles I’m running soft +2” length. But they don’t really lift the vehicle. They would be a standard spring rate so give max 1” lift. The long spring is good as it gives more travel before it unseats. Heavy Duty lift springs are terrible! Poor on road ride normally and will resist flex. But watch for coil binding if the spring is too long though.
I also don’t always run springs in their proper places. Ie I have rear springs on the front…
Dislocating suspension is fine. But if you can keep the spring seated the better. But beyond a certain point the spring will not be long enough. Lots of different dislocation or relocation options. All have pros and cons.
It looks like Terrafirma do a long arm Watts linkage. This might be aimed at big lifts. But lots of travel may also run into the same issue. So I’d say something to consider.
Interested to see how you get on.
Here is one of my past vehicles, a leafer. But an example of running rear springs on the front. It looked mostly standard with minimal lift, but it flexed really well and was lovely balanced front and rear. And would crawl over technical terrain easily and impressed a number of spectators.
I’m a big believer in having compression and droop available. And this setup did both.
My current project is still a work in progress. The suspension is actually quite basic. It also has lots of compression and large tyres will hit the rear seat boxes. More rear travel is available with a few more mods. But it flexes pretty well for now.
And something a little closer to your vehicle. This is my p38. Not built as a flex monster. In fact it wasn’t even meant to be lifted. I converted to coils and the kit claimed a 30mm lift which turned out to be more like 120mm lift.
The p38 could go quite high on the EAS though. Especially in the beached super extended mode. So it has thus far been fine with stock propshafts. It has linger brake lines and +2” shocks.
It flexes and keeps the wheels on the ground very well. It also rides technical terrain better and more comfortable than the EAS used to when in the raised height. The extra lift also massively helps with ground clearance and the poor departure and break over angles that the D2 also suffers with. Previously it would often hit the rear bumper and would easily get beached. The lift has mostly solved this most of the time. So while I normally wouldn’t go for a 4”+ lift. It has worked well in this instance. I’m also still running factory anti roll bars with factory anti roll bar links too!