strut mounting, strut monting

[kenhall1202]

Hi John,

I checked my 2008 copy of the Citroen Service Doc Backup disc and the change you mentioned above at RP7322 (25/11/1996) appears to apply only to the suspension cylinder and not the strut top. I'm wondering if this strut design change coincided with full adoption of the increase in piston diameter to 25mm?

Can any owners with RP's later than 7321 confirm what strut sizes they have fitted?

Ken

This post has been edited by kenhall1202 on February 06, 2011 12:46 am

[xmexclusive]

Further to Ken's request please specify engine type and ORGA as this would help tie things down. I had similar problems with tracking down the Bendix/Teves cut over to ORGA 6741. Car checks focused things down then I realised the relevance of the new engine bay LHM pipework introduced at that date.

Hi Ken
I find difficulty in believing that Citroen would introduce a new deep skirt 23mm strut head to be used for just 125 days.

John

[kenhall1202]

QUOTE (xmexclusive @ February 06, 2011 01:06 pm) 

Hi Ken
I find difficulty in believing that Citroen would introduce a new deep skirt 23mm strut head to be used for just 125 days.

John

Hi John,

I don't understand this interpretation - my suggestion was that the strut top design change to the deeper/wider bellmouth was made from RP7196 (20/7/1996) onwards (initially it may not have been universally applied to all models), but the design continued unchanged until the end of XM production in June 2000 (not sure when in June but the last XM ORGA/RP number would be somewhere between 8607 and 8636.

I believe that my spare one (of 2) shown in my photo above was made in 2001 after XM production had ended.

Ken

[xmexclusive]

Hi Ken

You cannot enlarge the strut rod diameter without a matching strut head with the wider holes for the different taper.
Accoring to the microfiches from ORGA 6444 to ORGA 7321 XU10JTE, ZPJ4, ZPJ, XUD11ATE, DK5ATE & XUD11BTE were all using the same struts.
That is clearly nonsense as the DK5ATE was large strut from 1994 while the others were not.
The strut top information shows the same list of models using item 5271.88 to ORGA 7195 and fails to say what is used after this. It does give the cylindr boot types as changing over at 7195. So that matches up to the strut top change.
It looks to me as though we need your call for actual car checks to add information.
We also perhaps need to search a bit deeper in the Citroen documentation and make sure we reference actual source of each bit of information we gleen.

Went searching this evening and found a new strut head to the later design.
This was actually for a non hydractive car so it took a small 23mm strut rod.
Looks like Citroen did modify the design of all 3 types of XM strut head.
The change was to lengthen the metal centre by 15mm and form a wider metal flange around the outside at the bottom.
It most likely will stop pop through on failure by axial tearing but because of the lower position of the flange may well allow 25mm vertical movement of the top of the strut rod. May still bend the bonnet a little bit as the rod top has less than 10mm clearance. I suspect that this new strut head centre design made it the same as the bottom of Xantia centres. The revised XM strut gaiter is identical to the Xantia one.
The original XM strut gaiter had a habit of dropping away from the strut head. The revised design makes it much more difficult to remove the gaiter.

John

This post has been edited by xmexclusive on February 08, 2011 01:04 am

[marc61]

Hi

Just wanted to say didnt Citroen solve this problem in about 1955, by designing out any rubber components in the suspension system?! So one solution would be to design an adaptor to enable a conventional Citroen suspension cylinder to be mounted sub flush via the 4 mounting holes hanging down in the plane of the XM strut. The drop link from the anti roll bar would drive, via a pivot arm, the pushrod in a conventional Citroen suspension cylinder (DS, CX etc) with a sphere screwed on top. The adaptor might be designed to allow the sphere to screw down into the gaping hole where the strut assy passes through. The only clever bit would be to design the adaptor so that it held and located the pivot arm at the correct position to transmit drop link movement to the pushrod. But there are plenty of clues in the design of a DS, GS front suspension to get it right. The amount of movement is relatively small, the suspension cylinders well proven, the fluid transmits the force to the sphere - no rubber to fail! The only thing that messes up the XM strut is all that stress caused by it being connected to the hub and roll bar when the steering is moved.

Apologies this is a bit left field. Just find it so ironic that today we end up with problems associated with rubber components that Citroen engineers successfully designed out of their suspension systems 50+ years ago! My strut tops are ok at present, but a proper hydropneumatic solution that dropped in place basec on a CX or DS susp cylinder would be a nice option.

Cheers

Marc

[citroenxm]

Thats an interesting thought really, Ive never got close enough to CX's and DS's to study the Struts and sphere mountings, because I love them soo much Id want one more and more, but, arent the front ones simmilar to rear XM/Xantia ones, with no angled top...

Its obviously the move to McPhersion sturt that forced them to change the fronts...

Paul

[kenhall1202]

QUOTE (xmexclusive @ February 06, 2011 07:28 pm) 

Hi Ken

It most likely will stop pop through on failure by axial tearing but because of the lower position of the flange may well allow 25mm vertical movement of the top of the strut rod. May still bend the bonnet a little bit as the rod top has less than 10mm clearance. I suspect that this new strut head centre design made it the same as the bottom of Xantia centres. The revised XM strut gaiter is identical to the Xantia one.

John

Hi John,

I totally agree with that conclusion. From a driving safety point of view it would be a big improvement to stop total 'pop through', however as you say the limited clearance above the strut top would inevitably still result in a somewhat less bent bonnet.

Ken

Re CX and DS (and GS and maybe Traction Avant) front suspensions - Both models had the classic double wishbone arrangement with a simple hydraulic cylinder design similar to the rear suspension. The cylinder with the sphere on top was anchored in the subframe and the piston acted downwards on the middle of the upper wishbone. This design was probably dropped for cost reasons and has been widely adopted by most car manufacturers.

This post has been edited by kenhall1202 on February 09, 2011 11:58 am

[Mark Hughes]

Hi,

I'm a new member, having just purchased a 2000 2.1TD VSX. Just catching up on what the issues are. Has XM Exclusive received his reconditioned strut tops and if so, are they the answr to the problem?

[xmexclusive]

Hi Mark

I am satisfied with the quality of the repaired strut heads but they have not been fitted yet. Unfortunately this is an item on which each individual must make their own technical evaluation to determine suitability.
If you look back through the threads you will see the discussion that decided this.

John

[Mark Hughes]

Thanks John. I'm just trying to anticipate the issues. The struts on my car are working fine but there is some rust visible on them.

Mark

[citroenxm]

Hi Mark, Welcome!

Is not the upeer outer shell thats important under the bonnet, these give NOTHING away, its more of a clue under the wing, in the wheel arch!!

If they are bad, you will see the rubber getting push out and downwards!!! If they are like this they NEED dooing, I can proove this with one of my own tops, it looks "OK" on the top, but it Has popped up...

Its over on the Other fourm ... Here

Paul

ADMIN: My appologies if I have violated a cross fourm pointing.. I or you may remove this of you wish..

This post has been edited by citroenxm on March 09, 2011 10:24 pm

[White Exec]

Having read Norrie's excellent Draft Repair Manual for front strut mounts, I'm trying to put together some proposals for preventing strut burst-through. Can anyone help me with some small bits of information? (The part nos. refer to the components in Norrie's paper.)

1. Do we know the diameter of the top opening of Anchor Plate (pt2)? Has this ever changed between early and late ORGAs?
2. And diameter of Lower Cylinder (pt1) lower bellmouth? I think this is 98mm (?) for late ones, but what diamater was the earlier version?
3. And lower protrusion of bell bottom edge, below baseplate? New and old?
4. Finally, the Draft Repair Manual from October details Part 2A, and how to fit it. But can this be fitted to a good (complete) late-type lump, with the larger bell mouth? How would it fit over it?
5. And finally, do we know the extent of vertical travel that the Lower Cylinder experiences in normal use - i.e. by how much (vertically) does the rubber have to flex?

Chris

I hope that John and Ken might be able to help me here!

This post has been edited by White Exec on March 10, 2011 04:52 pm

[kenhall1202]

Hi Chris,

Here is what I can answer based on the late type strut top pictured in my Feb 4th post

Q1 Approximately 85mm (difficult to measure directly because of the splash shield). May be smaller ID than early type - John will know the answer.

Q2 Bellmouth is about 100mm diameter over the metal. Early ones are smaller but don't know the exact size - John will know. The parallel section of the lower tube is approximately 88mm external diameter over the rubber coating.

Q3 Approximately 28mm. Old type less than 10mm?

Q4 Unless the strut top was dismantled down to it's separate parts the only way I can see of fitting a reinforcing top plate 2A would be to weld it up in position from two halves. (Like the Swedish method?)

Q5 Vertical travel - my guess 5mm or less for strut rubber in good condition - remember the clearance between strut rod top nut and the bonnet is quite small (less than 20mm?) I did measure it one day using some plasticine but have lost the measurement!!

I don't wish to discourage your efforts but it does seem to me that the Latvian repairers that John has used have addressed many of the strut design concerns and we await his evaluation of the polyurethane equipped strut tops with interest.

Ken

This post has been edited by kenhall1202 on March 10, 2011 06:59 pm

[White Exec]

Thanks, Ken - these figures are really helpful.

One other question: Part 4 is usually simply referred to as a "dust shield" or similar, but do you think it could play any part in limiting rebound - i.e. limiting downward travel of suspension?

John: Do we have any info on how Latvia have redesigned the unit - or have they simply substituted polyurethane onto existing original (serviceable) metalwork ?

Chris

[xmexclusive]

Hi Chris

The dust shield is just that.
On the XM it is metal.
On the Xantia it is made from ABS plastic.
Cannot remember about the C5 but will update this when I check.
With the original Latvian process the dust shield was removed.
We specified it be retained on the remanufactured units.
To fit in with the repair process it needed pressing to a new shape.
I used a series of questions to arrive at an understanding of the redesign.
These included cross-sections showing the steel rings added.
So it is not just polymer substitute.
Most of the information sent me has also been placed on the two XM websites.
As far as I am concerned strut pop through has a number of causes.
Pure axial tearing of the rubber is far less common in the UK than elsewhere.
Our corrosion problems can lead to rubber release through an enlarged baseplate hole.
The UK Xantia suffers this in the extreme.
No amount of redesign and extra protective steel work will prevent this.
I am satisfied that poor design and manufacturing process are the cause of these corrosion problems.
I therefore investigated how the Latvian process differed.
First check was on the dynamic performance of the polymer compared to rubber.
These matched closely and varied directionally as the Citroen rubber does. This was an area where I had some doubts about Noz's proposals.
Then I looked at material preparation, rust treatment and polymer bond to steel.
I considered these were all superior to the Citroen process. I estimate that the preparation and bonding will give a much longer life to the remanufactured head.
I then had concerns about the risk of in service polymer cracking leading to axial failure as the rubber does. On this I had to accept the judgement from the firms principal that the polymer selected is stronger in fatigue than the rubber. He based this on the firms considerable experience in remanufacturing other rubber automotive components. that have given better service lives than the originals.
I was also offered DMF refurbishment which apparently is a standard product line.

The above convinced me the remanufactured heads stood a high probability of giving good service in my intended use. There is now very little in the way of alternative options. In my opinion new will cease to be available fairly quickly.
Secondhand will quickly reduce to only poor condition, short life ones available before the supply dries up completely. Even if these refurbished ones only give half the working life they could be the only viable option to keep an XM running.
I think my batch of UK strut heads required a lot more weld repair work than the local ones they had previously remanufactured. While this extra work does not seem to be a problem they are prepared to have a batch of new steel baseplates manufactured if it is decided that is essential. There would need to be a fairly large volume order to justify the new baseplates.

John

This post has been edited by xmexclusive on March 11, 2011 10:47 am