ACE Roll bar too stiff for off road

I like the ACE anti roll system and what it can do. However, when off road, the anti roll bar is way too stiff for good articulation/flex. Has anyone figured a way of reducing this stiffness? Or perhaps employed quick disconnects? I came across the "X Deflects" quick disconnecting anti roll bar for the defender which seems like a good idea. However it is not for the ACE system nor is it available for the front axle (strange).

Also found this Australian company doing the same thing.

ACE should be soft for off road use. Are you sure it is working correctly and have fully validated that it really is too stiff?

As a rule the D2 radius arm suspension doesn’t tend to flex as well as the older A-arm setup found on a Defender/Disco1/RRC.

Not saying they can’t be made to flex. But you’ll have to work harder. And don’t forget the Watts linkage could also be an area to look at.

I'm fairly confident my ACE is working correctly. Its definitely softer when in low range/CDL. However, when you compare it to defenders it still seems stiffer with more wheel lift etc.

Am I right in assuming the ACE is active only on road in high range? I'm guessing the hydraulic ram becomes inactive and simply locks up in low range essentially simulating a conventional anti roll bar.

WHat would the best approach be in order to increase articulation for an ACE D2? Would it be a bad idea to mechanically disconnect the anti roll bar when off roading?

Gingerbread said:

Am I right in assuming the ACE is active only on road in high range? I'm guessing the hydraulic ram becomes inactive and simply locks up in low range essentially simulating a conventional anti roll bar.

Click to expand...

When off road under 25mph the ACE doesn't lock up, it goes soft. It's better than a normal ARB off road.

Gingerbread said:

I'm fairly confident my ACE is working correctly. Its definitely softer when in low range/CDL. However, when you compare it to defenders it still seems stiffer with more wheel lift etc.

Am I right in assuming the ACE is active only on road in high range? I'm guessing the hydraulic ram becomes inactive and simply locks up in low range essentially simulating a conventional anti roll bar.

WHat would the best approach be in order to increase articulation for an ACE D2? Would it be a bad idea to mechanically disconnect the anti roll bar when off roading?

Click to expand...

I haven’t owned a D2. So some of this is assumptions. But I have heavily modded other Land Rovers for flex.

As said, the A arm setup of a Defender tends to flex better. Certainly out of the box. On a Defender (or Disco 1/RRC) the rear A arm setup flexes a lot better than the front axle c cup radius arm setup. The D2 is in a way running the same sort of front suspension design on the back and front axles. But with more enhancements. I would also say the D2 was designed with a more balanced suspension in mind and more bias toward better on road manners.

The big question is, what is your plan for the vehicle? What are you trying to achieve? And what is your intended use? And are you willing to spend the money to attain your goal? As it could get pricey or require serious modifications.

Also note that while flex is great off road. Other attributes can help too. Fitting some limited slip or locking diffs might make all the difference off road.

Now I’m not saying the the anti roll bar isn’t restricting flex. Ultimately any anti roll bar, including ACE is designed to reduce roll. And will impact suspension travel. Lots of Defenders do not have anti roll bars at all though. So ARB’s limit flex in the willingness of allowing the axle to move and there will be a physical limitation in how much movement an ARB has. Although stock setups are unlikely to reach this hard limit.

Therefore it is perfectly reasonable that ACE may cause some restriction to movement. But I would guess ACE was designed to match or exceed fixed anti roll bars on lesser D2’s. So here is the big question again. What is your real plan with the vehicle? Are you prepared to impact road use for more flex?

What you need to do is figure what is limiting your suspension travel. Springs and shocks can sometimes limit travel. On the Defender rear A arm, simply fitting longer shocks gives more travel. But the same isn’t true on the front axle, as there is another limitation you hit first. You can get more flex at the front and make use of longer shocks. But you need to change some other bits.

On a Disco 2 you need to see what limits the axle. Dropping a shock off and seeing if the axle moves more is pretty easy. And will tell you if longer shocks will get you more travel.

Note that more travel may require longer brake lines, you don’t want to stretch or break them. Springs may also fall out with more travel, so retaining a spring or longer springs might be needed.

I’m convinced that more travel can be had from the D2 setup. But you need to see where and what stops the axle moving down. Which could be the anti roll bar, could be one of the suspension links or even something like the Watts linkage.

D2’s have been around for a while. So I’m sure with some research you’ll find setups that work. But don’t just go for the most obvious “lift kits” if you want flex. Lots of suspension kits ruin flex and off road performance. Just offering a stiffer ride and increased ground clearance.

Out of the box the D2 is quite capable though and some well chosen mods should make it even more so.

I have managed to put a wheel up high under each arch diagoinally, so I am sure it is pretty flexible, never lifted a wheel except on hard cornering on road (inside front can lift)

300bhp/ton said:

I haven’t owned a D2. So some of this is assumptions. But I have heavily modded other Land Rovers for flex.

As said, the A arm setup of a Defender tends to flex better. Certainly out of the box. On a Defender (or Disco 1/RRC) the rear A arm setup flexes a lot better than the front axle c cup radius arm setup. The D2 is in a way running the same sort of front suspension design on the back and front axles. But with more enhancements. I would also say the D2 was designed with a more balanced suspension in mind and more bias toward better on road manners.

The big question is, what is your plan for the vehicle? What are you trying to achieve? And what is your intended use? And are you willing to spend the money to attain your goal? As it could get pricey or require serious modifications.

Also note that while flex is great off road. Other attributes can help too. Fitting some limited slip or locking diffs might make all the difference off road.

Now I’m not saying the the anti roll bar isn’t restricting flex. Ultimately any anti roll bar, including ACE is designed to reduce roll. And will impact suspension travel. Lots of Defenders do not have anti roll bars at all though. So ARB’s limit flex in the willingness of allowing the axle to move and there will be a physical limitation in how much movement an ARB has. Although stock setups are unlikely to reach this hard limit.

Therefore it is perfectly reasonable that ACE may cause some restriction to movement. But I would guess ACE was designed to match or exceed fixed anti roll bars on lesser D2’s. So here is the big question again. What is your real plan with the vehicle? Are you prepared to impact road use for more flex?

What you need to do is figure what is limiting your suspension travel. Springs and shocks can sometimes limit travel. On the Defender rear A arm, simply fitting longer shocks gives more travel. But the same isn’t true on the front axle, as there is another limitation you hit first. You can get more flex at the front and make use of longer shocks. But you need to change some other bits.

On a Disco 2 you need to see what limits the axle. Dropping a shock off and seeing if the axle moves more is pretty easy. And will tell you if longer shocks will get you more travel.

Note that more travel may require longer brake lines, you don’t want to stretch or break them. Springs may also fall out with more travel, so retaining a spring or longer springs might be needed.

I’m convinced that more travel can be had from the D2 setup. But you need to see where and what stops the axle moving down. Which could be the anti roll bar, could be one of the suspension links or even something like the Watts linkage.

D2’s have been around for a while. So I’m sure with some research you’ll find setups that work. But don’t just go for the most obvious “lift kits” if you want flex. Lots of suspension kits ruin flex and off road performance. Just offering a stiffer ride and increased ground clearance.

Out of the box the D2 is quite capable though and some well chosen mods should make it even more so.

Click to expand...

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


x-springs


Anti roll bar disconnect front only:

Gingerbread said:

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

Click to expand...

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!