I was watching a YouTube video that Marty sent me last night where Tiff had the Overfinch P38 on Top Gear.

He referred to the ART system that Overfinch fitted (Active Roll Technology) and then showed a shot of the wheel arch:

You can clearly see a big green ball in the wheel arch which looks exactly like a Citroen sphere that was half filled with Nitrogen for damping.

In the 90's, Citroen had a system that they called "Activa" which used active hydraulic rams instead of drop links to ensure that the Xantia's that it was fitted to didn't body roll. There was never more then half a degree of body roll.

http://www.citroenet.org.uk/passenger-cars/psa/xantia/xantia-5.html

I wonder if Overfinch retrofitted this system to the P38? Top Gear said they charged £9k to do the work so I can't imagine they did it to very many P38's!

Does anyone have any information on this setup? I'm really curious how they did it and how they integrated the Citroen setup onto the car. I won't do it to mine as it's not worth it but I'm really intrigued at what they did and how they did it.

Googling reveals very little unfortunately.

David.

dhallworth wrote:

You can clearly see a big green ball in the wheel arch which looks exactly like a Citroen sphere that was half filled with Nitrogen for damping.

Nearly but not quite. Unless the Activa system was different, the Nitrogen gave the springing, the damping was done by washers with small holes in them to restrict the flow of the LHM hydraulic fluid into and out of the sphere. So no actual dampers at all. It used to be common to see an old Citroen bouncing along the road because the spheres had lost their Nitrogen and the only springing was in the tyre sidewalls! Back in the day, before they became highly collectable and fetch silly money, I went through 5 assorted Citroen DS models and a couple of CXs (never being one to stick with anything simple). There was a guy that lived near me who had been a design engineer working with Christopher Cockerell on the development of the hovercraft who designed and built the first rig for re-gassing the spheres. He was a very useful source of knowledge and spares (of which I needed plenty). He sold a lot of his stuff off to Pleiades, who are still based in the next village from me and are one of the few places that still do parts for the older Citroens. The height sensors were mechanical valves that opened and closed to allow fluid to whatever corner needed it with no electronics involved at all, just a 7 piston pump supplying fluid at 2,500 psi! Roll Royce also fitted green Citroen spheres to the Silver Shadow but to supplement the conventional springs and make the suspension self levelling.

The spheres had the hole drilled into them, there weren't any washers on them. Well, not on the stuff from the 80's onwards that I've had. The size of the hole varied depending on the position of the sphere on the car and the model of car it was on, as did the pressure of the Nitrogen in them.

I've had Citroen's for years and still do, including the Activa model I mentioned. It's an interesting system and is actually pretty damn simple when you understand it. It's very handy having the recharging rig, pressure tested and all the related tooling to maintain them as not many places will touch them through fear of cocking it up.

The basic Citroen systems had 6 spheres, the hydractive ones had 7 spheres and the Activa's had 10 spheres.

David.

I think the original system on the DS only had 5 spheres, one on each corner and one on a pressure regulator. All of the ones I owned had the hydraulic gearbox so a manual gearbox but the gearchanges and clutch operated by the hydraulics. Got interesting when it lost pressure as it shut things down in order of importance so you'd lose the gearchange, then the suspension, then the power steering and finally the brakes (although thinking about it, you could very well be right and there may have been another sphere on the braking circuit). Still got the workshop manuals somewhere, although I can't see myself ever owning another DS, brilliant engineering but made from the poorest quality, most corrosion prone, steel ever produced, you could watch it dissolve while parked in the rain.

From what I recall it displaces the Anti roll bar and shockers to lessen the body roll and twisting..

It still has air ride..

I can't see a swashplate pump.

A chap on Landyzone owns a lovely 630r,

I wonder if you could retrofit ACE from a Discovery.

Just what I was going to suggest.

I’ve had 3 with Ace and even with a 2” lift it works a treat.

There's a lot of people who remove it on the Disco 2's due to the problems with rotten pipes and valve block failure though so it's probably not worth it.

I'm asking out of curiosity rather then looking to implement something.

David.

Lots of people remove the EAS on P38's, but most of us here think EAS is worth it. My D2 doesn't have ACE, so I don't know if ACE is worthwhile.

I have a disco 1 With a 2 inch lift and it used to roll all over the place.

The disco 2s that were fitted with ACE are far superior in handling and even the one with the 2 inch lift hardly rolled at all. Well worth having in my opinion.

We had a Disco 1 at work from brand new and as it had a 10m telescopic Clark mast on the roof, it was a bit top heavy. At the time LR did a rear anti roll bar as an option and we had that fitted which made a hell of a difference to the amount it rolled on corners. Still didn't stop one guy from rolling one though which resulted in H&S recommending that everyone that drove one got sent to Solihull to do an off road driving course. Not one of us complained, I'd have happily paid to do that course.....

The Disco 1 was replaced with a TD5 D2 when the time came and that had ACE fitted. Not sure if it made any difference to the roll, I thought it only supplemented the springs to give self levelling?

Not self levelling, that was another option that used air spring(s?) on the rear. ACE is something like Active Cornering Enhancement, to limit body roll while cornering.

Gilbertd wrote:........ brilliant engineering but made from the poorest quality, most corrosion prone, steel ever produced, you could watch it dissolve while parked in the rain......

Interesting one that, .. having lived in Scotland in the 70's and (Kingston upon) Hull in the early 80's I saw a number of French and foreign vehicles rust away, ... apparently made of inferior material ... except that when I moved to rural SW France in the 00's, I saw many of the same (by then 'vintage' or classic) R4's R5's CX's etc still in daily use! it seemed to me that the French automobile industry simply failed to accout for UK weather and winter salt ??

I remember reading a report once years ago, after the Lancia rust problem came out. It seems that in those days car manufacturers were using reclaimed steel for body panels. Someone sent a brand new Alfa body panel to a laboratory who tested it and found it was something like 80% ferric oxide so no matter how much protection you put on the outsides of the panel, it would still rust as the rust was already in it.

On a DS21 Citroen I owned I spent days welding an old filing cabinet into the underside. The sills were square section about 6 inches square and the bottom would rot out on them. I plated all the bottom and outer sills and even bolted through and put L sections on the inside where it joined the floor. The fuel tank lived under the back seat so that had to come out while I was doing the welding and after I'd finished it, put the fuel tank in but didn't bother with the rear seat. Drove it down for MoT which it sailed through only to notice on the way home that the C pillars were wobbling around from side to side. It was only the back seat that was stopping the back end from waving around in the breeze! The join between the C pillars and sill sections had rotted away too. Fortunately all the outer panels on a DS were bolted on and the VIN plate was held on with self tappers. So I bought another that had rotten outer panels (and had been treated to a silver Hammerite, brushed on, paint job) and swapped the VIN plate, number plates and all outer panels from one shell to the other. Kept the old VIN plate in the glovebox in case I needed to buy any spares as on was a DS21 carb and the other was a DS23EFi........

Land Rover Discovery 2 ACE System

ACE is an abbreviation for Active Cornering Enhancement, this is part of the suspension system.

ACE is and electronic and hydraulic system that uses sensors and an ECU to activate a hydraulic cylinder on the front and rear anti roll bars to keep the vehicle level when cornering. When working the ACE system is excellent and makes the ride and road handling more like a normal car rather than the handling of a tall, heavy SUV.

An extract.

The ACE system consists of many components including:

High pressure hydraulic system

Fluid reservoir
Hydraulic pump
Pipes
Control valve
Filters
Rams
There are many parts to the ACE system and all can be troublesome in one way or another. Basic maintenance involves changing the filter every 72,000 miles, part number RVJ100010 and checking the high pressure pipes for corrosion. The metal pipes are prone to corroding and leaking, replacement pipes are expensive and difficult to fit. So much so that many owners prefer to disable the ACE system rather than repair.

The 7 seat versions of the Disco 2 should have air springs on the rear from new. I gather the difficulty with the ACE pipes where its fitted, is that they run ontop of the chassis so access to them is difficult (To the point of needing to remove bits of the body to replace some of them). And it can have rear air springs without ACE as well. Its very believeable that they suffer from corrosion, as the rest of the underside of them does as well as most here will already know.

All my discos were ES models. These were all fitted with self-levelling suspension at the rear and the ACE system.

I covered well over 100,000 miles in total on the three vehicles, most of that on the TD5 model. I never had any problems with the ACE System although when I sold that car it was a mere 14 years old and had covered 170 K. So reliable yes In my opinion.