Evolution: Xantia Hydractive Suspension Regulation - Info

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Stickyfinger
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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by Stickyfinger » 02 Jul 2016, 19:38

Mandrake wrote:Not sure what you mean - the change over to the new valve design is well into the S2 run - March 1999. You won't find any S1 cars with the new valve design unless they had a faulty valve replaced after 1999.
Ah...Ok.

Wonder if the S2 V6 I have all the bits from has it.

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by Mandrake » 02 Jul 2016, 23:20

Mandrake wrote: So I think if I was to attempt retrofitting I'd get the new valves and the hydractive strut pipes that go with them and swap the lot over.
A possible easier alternative has just occurred to me. :)

On the Hydractive regulator blocks, the ports where the large hydraulic pipes enter are actually removable "plugs" which you can easily remove with a large socket once the pipe itself has been removed. (item 14 on the diagram) The plug is threaded and has a large o-ring on its outer diameter to seal against the body of the regulator block, and clamps down on top of the damper valve inside, which can also be removed once this large plug is removed.

I don't know if this is the case or not, but it seems very likely that the "plug" on old and new regulators shares the same outer diameter and thread where it mates with the block, but with a different inner bore and thread for the pipe itself. In other words the difference for taking the different pipe fittings is entirely contained in the removable plugs.

Thus the special "replacement parts only" version of the new regulator to fit the pipes in older cars is nothing more than a new design regulator fitted with the old style "plugs" installed in the large ports instead of the newer type plugs.

If that's true then we could simply take one of the new regulators (type 3 in my list above) from a post March 1999 car and take the existing plugs out of the old regulator and fit them on the new regulator to make it compatible with the old pipes. =D> Then block off the pipe from the anti-sink valve and the conversion is complete. :)

Of course the brake bleed valves needed to block the no longer required anti-sink ports are also NFP... and its possible the mounting bracket for the regulator block might require modification if it doesn't mount quite the same way - not sure about that, but neither are insurmountable problems.

If anyone has both a new style and old style regulator in their spare parts bin can they confirm whether the large plugs are indeed interchangeable between the two types ?

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 03 Jul 2016, 07:33

Simon,

I slept on this overnight (wife will kill me for the oily marks on the pillow), and wondered about just that - whether, given a late new-type regulator and an OE one, whether a hybrid could be put together.

Am very tempted to pursue this, and must now go looking for a couple of suitable regulators. More than happy for you to get there first!!

Atb,
Chris

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 03 Jul 2016, 10:34

Simon,

See that all three types of regulator are now NFP.
The latest type (RP8155-->) "internal pipework" regulator - can you confirm this is pt.no. 5277 10 ?

At least it would be easily spotted at a scrappie, by the flats on the spring/shuttle-valve plug, plus RP number.

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by bobins » 03 Jul 2016, 10:55

How do C5 ones compare ? Would they provide a basis for a swap of fittings ?

Image

http://www.ebay.co.uk/itm/New-OE-Genuin ... SwNuxXbAIJ

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 03 Jul 2016, 16:21

Do we know about the workings of those C5 units?
Are the solenoids electrically identical to Xantia-XM ones? 12v/~3v/1kHz?
Could pipe connection bushes be swapped?

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by aerodynamica » 26 Sep 2016, 20:51

After all these weeks I had a closer read of the documents provided (thanks Marc) and of Mandrake's discussion and I see what they've done too. I was initially wondering about the compatibility if these modified units to the original 'sinker' Xantia without the anti sink valves mentioned in the document. But on further analysis it looks like it's actually even easier to fit these units to the sinker as the hydraulic feed to the regulator that is deleted is actually just a pipe that is a T junktion off the supply to each height corrector, front and rear. I'm thinking delete the pipe, blank off the port on the T or replace the T with a straight joiner, possibly swap over the two retainer plug/ adapters à la Mandrake's suggestion and then it should work.

I'm keen to give this a go. Does anyone have a RP8155 and after regulator for sale? (or two but I'm keen on doing the rear first)

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 26 Sep 2016, 21:23

I have delayed writing up my trial conversion (2.5 XM) to these later-type regulators - which I did a week or so ago - simply because of some silly problems which arose, and which I am currently rectifying.

I obtained a pair of the modified-type valves from a scrapped 2001 Hydractive Xantia, and will briefly add to Simon's earlier excellent posts and analysis:

- The large-bore pipe unions (connections to wheel spheres) are not an issue, in dealing with old-type pipe union, and new CITROEN-type coupling. Simply remove the unions from the existing valves, and place in the new ones. External and internal threading is identical, but the new type unions feature a rubber/brass olive and deeper drilling; previous versions do not have this.
- Removing these unions exposes the damper inserts, which simply fall/tap out. An identifying number is stamped either side of the central damper hole. Simply take the dampers from the existing vales, and fit them to the new ones, to preserve the damping characteristics of the vehicle.
- Blocking off pipework is as detailed in the Citroen working paper, for both Anti-sink and Sinker models.

The late-type Xantia regulators are of course NFP, and last sold at about €617.45+tax each, I believe. If you are going to try this conversion, start looking around early, as they might take a bit of finding. RP numbers etc are all in the working paper, i.e. RP 8155 (7Mar99) to Xantia end (2001).

I should be able to do a full report in about 3-4 weeks' time. Things are looking hopeful.

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by aerodynamica » 26 Sep 2016, 21:30

Well done Chris! I thought I was embarking on this on my own! Any positive observations to report for the impatient (me :D) ?

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 27 Sep 2016, 06:56

Also required are a couple of M8 bleed screws, to blank either the anti-sink valve (or union, depending whether sinker or not). Listed part is 1210 06, and is NFP. This part also used on many rear brake calipers.
An alternative new item just found could be 4428 13 (available) - the front caliper bleed screw for lots, AX to Cactus. Not sure whether this is M8 or not, though.
Such screws also available aftermarket. Also possible to modify an 25mm M8 bolt to do the job. Doesn't need to bleed, just block.

I think the whole job is one for a decent workshop ramp/flatbed lift (car needs to be 'on its wheels'), as the access is somewhat fiddly, although quite do-able. Not a job for lying on your back under the car.
Last edited by white exec on 27 Sep 2016, 08:50, edited 2 times in total.

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by xantia_v6 » 27 Sep 2016, 07:18

I am looking forward to a report on the results. Does the suspension now go soft when the door is opened after the car has been sitting overnight?

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 27 Sep 2016, 08:29

Yes, it does.

Bit of a pain, I know, not to be able to give a definitive report at this stage, but I need to refurb my front height corrector, and replace both front corner spheres. Should be able to do the HC in the coming week, but am having to wait for two genuine Citroen multilayer spheres until 2nd week of October (none at factory).

In the meantime, the 2.5 temporarily sports a pair of Accumulator spheres (at 50bar) on the front, simply so the car can be moved. I have also put some sea-sickness pills in the glovebox, and might well get a 'Please Pass, Running In' sticker for the back window, for the 20km journey to the car-lift workshop.

This is all a bit frustrating, but things are looking hopeful. The real test will be how the new valves respond to humps, bumps and nasty ridges, and whether they are more immune to hydraulic shocks and unwanted brief excursions into Firm mode.

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by GiveMeABreak » 27 Sep 2016, 08:49

I'm really looking forward to reading your next update Chris

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by white exec » 12 Oct 2016, 12:00

OK, here goes...

After a good bit of faffing about (you really don't want to know), the new "late Xantia" type suspension regulators are now fitted to the 2.5 XM, and this morning I did a road test.

Have to report that it really is rather good. Previously, the XM's suspension system was in very good shape, with all spheres at correct standard pressures, and working as well as it should, so there is something sensible with which to compare.

Left home along a km or so of uneven and rocky dirt rack, which I must admit felt a bit knobbly, reached our local village, and got on to tarmac. A few minutes later, the suspension noticeably settled down as some trapped air (the front corner spheres had been removed) worked its way out of the system. The drive down 8km of winding tarmac mountain road to the coast was lovely. Along it, I threw the car into a couple of fast bends, and the transition to Firm and back again (dash LEDs for the EVs) was spot on, and almost imperceptible - just as it should be.

Then on to the coastal motorway, and 15km to the next exit, some at 110km/hr cruise, and a bit at 140. Perfect ride, even over undulations and bridge-joints. Flooring the accelerator brought on a nice smooth change to Firm, again aok.

Back along the coast road: local traffic, lights, raised pedestrian crossings, speed humps and ridges. This was the real test, simply because this collection of moderate-speed lumps, bumps and ridges is exactly what Hydractive II has always tackled less than perfectly.

Well, it's better. Extended speed bumps (raised pedestrian crossings, two or three metres in length, and maybe 12cm high) can be taken somewhat faster, and without the system annoyingly going firm while negotiating them. I say "going firm", but this was previously not normally shown by the EV LEDs extinguishing. In other words, the EVs remained energised (Soft), but the ride told you different.

This is exactly what Simon identified in his excellent analysis of the new-type valves - that they should, theoretically, be more immune to system pressure fluctuations and ridge-induced shock-waves, because the regulator shuttle valve is held in position by internal sphere pressure and the new spring, and not by line system pressure. All I can say is, this seems to be so. Unless the car is driven deliberately fast over a raised and elongated hump (when there will be a thump), at decent speeds the car just takes it in its stride, with no crashiness or thump, and, most pleasing, no crash when the back wheels clear the obstacle, just a soft descent. Bingo!

Then back up the 8km of mountain road to our village - all good - and again on to the 1km of rocky dirt track. This last was handled far better than the outward journey, with the suspension nicely mopping up the rocky knobbles. Air-in-system presumably gone, and everything warmed up.

So, it's looking good. Worth the effort of changing over? Yes. It was good before, but now it's subtly better, and that's welcome.

What I will do is put together a technical write-up about fitting the replacement valves. There are a few dodges and cautions, and a good bit was learned along the way.

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Re: Evolution: Xantia Hydractive Suspension Regulation - Info

Post by GiveMeABreak » 12 Oct 2016, 12:10

That sounds like an excellent result Chris - It looks like all the effort has paid off and I'm really pleased the ride seems better. It seems that document was a bit of a find then! One for the wiki when you've had a chance to further road test and write it up. =D>