Dynamic Stability

[RainHard]

Hi All,

does the Dynamic Suspension (where fitted) on the D3/D4/RRS work like that of the D2 where at low speeds it disconnects the sway bar and you have more wheel articulation than a standard swaybar?
The description I have states "it is inoperative below 3km/hr". Does this mean, it's disconnected or that it's not actively compensating for body roll - so like a standard/fixed sway bar?

"Below 25 mph (40 km/h) the percentage of road roughness calculated is used by the control module to limit the operation of the Dynamic Response system. At speeds above 25 mph (40 km/h) the system disables the percentage road roughness signal and full Dynamic Response system assistance is restored. The system is completely inoperative at speeds below 2 mph (3 km/h)."

[Tombie]

Considering it's essentially shock based it adjusts damping rates amongst a few other tricks.

Nothing like a D2 with ACE

[RainHard]

Apologies - maybe some terminology needs to be clarified:
Dynamic Stability - uses suspension and ABS
Dynamic Response - uses Active Stabilization System (if fitted).


The Dynamic Response system uses two accelerometers to detect vehicle cornering forces and inputs from the steering angle sensor to supply data to a dynamic response control module. The control module then operates solenoid valves in a valve block which apply hydraulic pressure to actuators fitted to the front and rear stabilizer bars. The application of hydraulic pressure to the actuators applies a specified amount of torque to the stabilizer bars to counteract the cornering forces and minimize vehicle body roll.

[gghaggis]

Right, so which does your original question relate to?

Cheers,

Gordon

[RainHard]

Right, so which does your original question relate to?

Cheers,

Gordon


We'll get there - eventually!!! Please read the extract below the question - it mentions Stabilizer bars...The control module then operates solenoid valves in a valve block which apply hydraulic pressure to actuators fitted to the front and rear stabilizer bars. The application of hydraulic pressure to the actuators applies a specified amount of torque to the stabilizer bars to counteract the cornering forces and minimize vehicle body roll.

[camel_landy]

It sounds to me as though there are a number of terms getting confused here.

'ACE' is available on the D2 but there is also a version available for the RRS (IIRC - Standard on the TDV8 & Supercharged).
'DSC - Dynamic Stability Control' is standard on the D3/D4/RRS.

Also, don't forget that the D2 is a live axle where as the T5 platform (D3/D4/RRS) is intepedent, though the air system is designed to mimic the way a live system works with the 'Cross-link valve'.

...and to muddy the waters further, the new RRS does some additional clever stuff in this area when off-road too.

So, I suggest we take a step back and ask the question: What are you trying to do? How did you get to this question??

M

[camel_landy]

We'll get there - eventually!!! Please read the extract below the question - it mentions Stabilizer bars...The control module then operates solenoid valves in a valve block which apply hydraulic pressure to actuators fitted to the front and rear stabilizer bars. The application of hydraulic pressure to the actuators applies a specified amount of torque to the stabilizer bars to counteract the cornering forces and minimize vehicle body roll.

That's 'ACE'. It is applying additional force through the hydraulic rams, to counteract body roll. The amount of force is calculated by the accelerometers mounted on the chassis.

These are not disconnected in any way.

M

[LandyAndy]

That's 'ACE'. It is applying additional force through the hydraulic rams, to counteract body roll. The amount of force is calculated by the accelerometers mounted on the chassis.

These are not disconnected in any way.

M

Not mechanically.However in low range the valving is opened to stop the effect of the anti roll bars.
I have a "patch" that I need to get around to fitting from a member here.It allows the unlocking of the bars in high range and at speed too.
Andrew

[RainHard]

Thanks Camel Landy,


yes it's the "ACE Equivalent" I'm referring to and the question relates. In the D2 below 10km/hr, in low range the ACE system disconnects the sway bar allowing more articulation. I'd like to know whether this occurs in the RRS version "Active Stabilization System". The reason I think it does is because they state "The system is completely inoperative at speeds below 2 mph (3 km/h)."

I suppose the question to be asked is... how does the swaybar limit articulation in an independent suspension system and will disconnecting it improve performance?

[101RRS]

Sorry I am a bit confused as well - are we talking about Dynamic Stability Control which is primarily application of brakes through the ABs system to correct skids and sideways movement, or

Dynamic Response which as I understand it is fitted to some higher performance models and is to over simplify an active sway bar type type system with a result similar to ACE.

Cheers

garry

[RainHard]

LandyAndy - you've nailed it! Where can I get that patch? Has anyone tried to compare "open valved" RRS ACE systems to Vehicles with "Standard Swaybars" and is there a noticeable difference?

[gghaggis]

The comparison is not valid for an RRS with Dynamic Response. Very different systems. When the DR is inoperative, it has no effect on articulation. When the cross-valve EAS is operational (in low range & some high range situations), it is the limiting factor for articulation.

Cheers,

Gordon

[LandyAndy]

Sorry,mine is for the D2 ACE system.
All the gizmo I purchased does is basically alter the speed signals to the D2 SLABS ecu.
Will PM you a link to the supplier and the thread.Perhaps a similar device can be made for later vehicles with a similar system.
Andrew

[RainHard]

The comparison is not valid for an RRS with Dynamic Response. Very different systems. When the DR is inoperative, it has no effect on articulation. When the cross-valve EAS is operational (in low range & some high range situations), it is the limiting factor for articulation.

Cheers,

Gordon

Thanks Gordon - so the "live axle" and "independent systems" are very different. On a "live axle" system you can gain extra articulation by disconnecting the swaybar. On an independent system (whether they have Dynamic response or not), the EAS is what links the articulation and is the limiting factor. disconnecting the swaybar will produce zero improvement.

[Tombie]

On a D2 with ACE disconnecting the bar will make no difference to articulation.

On a RRS, the vehicle will give you all it can as part of its programming.

On the D2, the ACE unlink module only releases the hydraulic resistance - the bar stays attached.

[Graeme]

The ability to unlock D2 ACE bars at higher speeds is achievable because the D2 uses a speed signal on a dedicated wire hence the speed signal to the ACE ecu can be modified. The D3 etc speed signal is distributed on the high speed canbus so in a practical sense cannot be modified.

BTW, the D2's ACE bar locking and unlocking has nothing to do with high or low range other than its difficult in high range to travel slowly enough to unlock the bars.

[camel_landy]

On the D2, the ACE unlink module only releases the hydraulic resistance - the bar stays attached.
^^^^ This....

Stop talking about 'disconnecting', it's just confusing the issue.

M

[RainHard]

I quote from a different forum..


I quote..

Taken from Range Rover Sport - Wikipedia, the free encyclopedia, and referring to the 2006-2013 Range Rover Sport:

Driving technologies[edit]
Dynamic Response incorporates active electro-hydraulic anti-sway bars which react to cornering forces and activate and deactivate accordingly resulting in sublime on-road handling.[citation needed] Dynamic Response also aids off-road performance by decoupling the anti-sway bars to allow maximum wheel articulation. The system in an evolution of the acclaimed ACE (Active Cornering Enhancement) system available on the Discovery Series II but is described as proactive rather than reactive. Positive Torque, a system standard on all TDV8 and Supercharged models, electronically blips the throttle, resulting in faster downshifts and the availability of vast reserves of torque. The speed sensitive steering system, adopted from Jaguar is standard on all models and there’s the option of active bi-xenon headlamps which act with the angle of the steering to aid vision. Active Cruise Control (ACC) with Forward Alert system incorporates an integrated front bumper radar which detects vehicles travelling ahead and adapts the vehicle’s speed to match. The system scans the road ten times a second, has a 16 degree field of view and Land Rover claims it is able to discriminate between a heavy vehicle and an adjacent lane motorcycle travelling at least 180 metres (590 ft) ahead.[5] Four preset distances are selectable and will ensure the Sport maintains the desired distance from the vehicle it is following.


So the swaybar disconnect will allow better articulation when offroad. I find it unusual that it would lock at speeds below.... because that is when you need the disconnect most. In my humble opinion, it disconnects when offroading, and therefore the term 'inoperative' suggest that the electro hydraulic system does not try control body roll when offroad at low speeds, so the swaybars remain effectively disconnected allowing better articulation.

Regarding disco 3 & 4, I was not aware that the disco's had active swaybars, I thought that was only available on the RRS.. Someone correct me please..https://www.aulro.com/afvb/images/imported/2014/02/1205.jpg

[Graeme]

Regarding disco 3 & 4, I was not aware that the disco's had active swaybars, I thought that was only available on the RRS.. No need for a correction - you are correct.

[gghaggis]

Rainhard, I'm not sure what point you're trying to make? The DR doesn't affect off-road articulation. A Sport with DR doesn't have any more articulation than one without. De-activating it just provides the equivalent.

Cheers,

Gordon

[Graeme]

The DR doesn't affect off-road articulation. A Sport with DR doesn't have any more articulation than one without. De-activating it just provides the equivalent.
From the wiki description, which may or may not be correct, the DR system replaces the standard sway bars so I suspect could affect articulation off-road. I'll find out more for myself one day as a brother today purchased a 2008 TDV8 RRS fitted with DR.

[gghaggis]

If it doesn't deactivate, I guess it could "fight" against the cross-valving. However, if working correctly, there is no obvious difference in articulation - we have a series of wombat holes we use on our training day where the cars are pushed well beyond their maximum articulation and there's no visual difference between the V8 with DR and the V6 without.

There's certainly a difference in the front axles' articulation when comparing a Sport and a D4 though.

Cheers,

Gordon

[101RRS]

There's certainly a difference in the front axles' articulation when comparing a Sport and a D4 though.

Cheers,

Gordon

Are we talking standard RRS vs standard D4 and if so what is the difference and why. I always thought the basic suspension was the same but I now understand there are some differences bit not sure why.

If they are different adds more weight to have a separate RRS section - not linked with the D3s/4s.

Cheers

Garry

[camel_landy]

The sway bars on the DR fitted RRS are different. Physically, the sway bar is in 2x sections, with a hydraulic unit in the middle. When pressurised, this unit locks both sides of the sway bar. IYSWIM

As for the differences between the RRS & D3/4... Yes, whilst essentially interchangable, the suspension is 'tuned' slightly differently.

M

[Graeme]

I had known about the 2-piece bar and that it locked rather than pushed against the lean as the D2 ACE does but was surprised to learn of the existance of an hydraulic oil reservoir similar to the D2's ACE reservoir, but now I know why.

Does DR on the RRS have 2-piece bars front and back or just on the front? I suspect both. I note that DR is listed as ACE on the RRS build info sheet.

[camel_landy]

IIRC - The bars are front & rear... and yes, it's also known as ACE.

M

[Stuart02]

Can anyone tell me why you would ever want to drive in 'Normal' mode rather than 'Dynamic' mode if your RRS has it, and if there's no reason not to, why does it mostly (but not always) have to be re-selected on start up?

Cheers