Strut Top Movement When Steering, Is some normal?

Is it normal, for the strut tops to move a very slight amount if you operate the steering when the car is sat stationary?

It certainly looks a bit disconcerting!

Yes. Due to the castor angle, ackermann angle and all those other suspension geometry terms that I know about but don't understand

Also articulates fore / aft slightly when you change the height lever.

Good good, thanks for saving me from a heart attack, Wirdy.

I really must get checking the tops properly.

Something that often makes me wonder, I hear of many very early S1 cars still on the original tops, and they seem fine, yet we're seeing quite a few S2s popping their bonnets these days. We all grimaced at that one on Ebay the other day.

I know corrosion etc will obviously play a part in strut top condition, but does it seem there are a larger frequency of S2 cars suffering failures?

This post has been edited by Ciaran on February 21, 2007 10:04 am

Hi Wirdy

I do not think the ratio is any higher with Mk2's it is just that some of them are reaching critical state. In my view there are two different ways XM strut head failure can be initiated even though the final failure mode is very similar.

With the first failure mode the main rubber block shears to form a cylinder of larger diameter but parallel to the strut rod that passes up through the centre hole in the metal strut head baseplate ring. Andmcits XM photo shows an example. This type failure in my opinion is caused by excessive loading on the rubber block from long term use of a seriously defective suspension driven to excess over rough conditions. It still takes a considerable time to work to actual failure so by this time the suspension most likely has been fixed and the car sold on. It seems to me from the reports I have seen that hotter climates make this mode of failue more common. To examine for this fault you need to look at the rubber block from the underside in the top of the wheel arch. You should be able to see all without disturbing or pulling down the rubber bellows fitted to the strut provided you use a small mirror to look at the back half of the block. It helps if you have examined the underside of a removed (good, clean) strut head first as there are two deep slots moulded into either side of the rubber block. At first look these can be mistaken for shear in progress. If shear is taking place then cracks will be evident across the bridges of rubber at the ends of the slots turning the slots into a full circle. If the circle is complete fit a replacement strut head promptly or start looking for a replacement bonnet in the right colour as well as the strut head.

With the second mode of failure the metal strut head base ring rusts away particularly around its top edge until the central hole becomes so large that the whole rubber block shears and lets the strut up through. The whole of the baseplate top is encased in rubber so it is NOT possible to examine the extent of this rusting on an XM. There is a thin layer of rubber on the top surface of the metal baseplate and I believe it is this design feature that is causing most of the UK XM strut failures. It is this rubber that you can see cracked and crazed around the top surface of the strut head, with rusting on the metal baseplate of the strut head underneath. This thin layer of rubber is a one piece moulding and joined to the main rubber block moulding. For some reason (rubber movement under load/ mill scale on the surface of the metal baseplate, not sure which) this thin top rubber layer peels from the steel and lays on top of it. Capillary action then sucks all the available moisture in and accelerated rusting starts. The extent of the cracking/crazing/rusing can indicate how far this process of rubber delaminating from the steel has progressed. It is only by removing the layer of top rubber that the actual condition of the metal baseplate can be examined for rusting. It is still a difficult judgement as to how much metal thickness remains. It seems that if the exposed metal is cleaned up and rust treated then the baseplate stops deteriating and may well have a good residual working life. Whilst I think there is considerable potential in cutting the top rubber away and rust treating I am only willing to do this on my strut heads when removed from the car and on a workshop bench. This is because of the care needed in cutting the top rubber away from the main rubber. The cut if not carefully done could put a slit in the main rubber at the shear plane position that strut heads typically fail at.

Finally a note about why Xantia struts commonly have a further different failure mode. The Xantia strut head baseplate bolts to the underside of the chassis unlike the XM which bolts to the top of the chassis. With the extra steel in the Xantia wheel arch Citroen decided to protect the underside of the strut head baseplate by coating it with a thin layer of rubber. Low and behold the thin layer of rubber peels a little, capillary action sucks in water and a high proportion of road salt in winter. The baseplate rusts heavily particularly where it turns up to encase the rubber block. This ring of metal can rust right through leaving the centre of the strut head free to pop up with the rubber virtually undamaged. It is very interesting to note that the underside of the unprotected XM strut head despite living in the wheel arch does not suffer corrosion anywhere near as much as the "protected" Xantia one.

Sorry, a long post but I hope it is found helpful.

Regards

XMexc

Hi XMExc.

Many thanks for that post, highly informative.
I have at home a replacement strut head for the Xantia, which has suffered the rubber delamination and rusting you describe.

This, is the top it will be replacing:



I'm wondering, would the Xantia tops benefit from removing the lower rubber coating, and treating the metal baseplate, as with the XM method for the upper rubber cone?

I'll have a good look at the new Xantia top and use it as a basis for comparison on the XM ones....
It does concern me that no matter how well you rust proof the metal, that rubber failure really can't be ruled out indefinately. Such a stupid, stupid design that is going to kill many of these cars in the coming years I suspect. Still, hindsight is a wonderful thing...
You would think though, that with the length of production on both XM and Xant, failures would have shown in good time for the strut design to be modified for later cars. I guess Mr. Accountant got in the way of that one...

Why don't CX, BX etc suffer from this?

I think I'm going to invest in a set of spare tops anyway, and treat them ready for fitting at some point in the future....

Cheers.

Ciarán.

Hi Ciaran,

The problem is to find some way of allowing for the articulation at the strut head that is inherent in the McPherson strut type of IFS, whilst also supporting the weight of the car and suspension loads. I suppose it would have been possible to design some type of all-metal ball and socket joint, but I suspect that even with Citroen's suspension there would be shock loading transmitted through with the probability of ultimate fatigue failure. So some form of rubber insulation would still be necessary. Rubber in compression/shear has a long successful history, e.g. as in the original mini, so I'm sure it seemed to the designers to be a good solution to the problem.

I'm guessing but I suspect that you require stiffer rubber for support than for the other head movement and that this is the reason for the two slots that XMexclusive mentioned. The designers obviously tried to prevent corrosion by coating everything in rubber, what a pity it didn't work.

The CX, like the GS series and the DS/ID before it, didn't have McPherson struts. The BX of course does, unfortunately I threw out my BX books during the last move so I don't know the details of the strut head design. Conventionally sprung cars react all the loads through the springs to the upper spring support so the design is simplified.

Derek

PS: My views on the design are all based on guesswork - I've never seen a strut head off a car!

This post has been edited by DerekW on February 21, 2007 04:17 pm

CXs do not suffer from this problem as they do not use Macpherson struts - they use arms etc instead, as did GSs and DSs (remember them?)

I have read that BXs in Malaysia suffered from the rubber heat perishing and popping the strut through the plastic bonnet.

If you get your glamorous assistant to spin the XM 's steering wheel from lock to lock whilst you stand viewing into the engine bay you'll see the strut tops do a merry dance which in a fudged, "that'll have to do" kinda way is the best the Xantia and Xm can manage.

On the other hand, the geometry of the D, G and CX models is a masterclass in how to engineer steering/suspension purely and correctly. It's no accident the suspension is a more reliable failsafe arrangement on these models and is available now on the £40k C6...

In it's day new in the early 70's "Car" magazine under the stewardship of LJK Setright likened the handling abilities of a G model to be vastly superior to many a supercar of the time!

Don't fight it - drive a GS asap - BEFORE IT'S TOO LATE AND THEY'VE ALL BEEN SCRAPPED!!

Andrew

This post has been edited by Andmcit on February 22, 2007 01:24 am

Pictures from davethewheel on FFC - Xantia strut in final stages before failure - just caught in time...

Andrew

Thanks for the information guys.
I must do some reading up on CX / other suspension setups actually, I don't actually know much about them...

Andrew, those pictures are frightening! I think the driver's side one in my Xantia is probably similar to that, certainly the underside has had it. Luckily the car is currently off the road and I have the replacement top in hand...

Another on ebay





I wonder how long it takes before someone actually gets badly injured or worse when one of these lets go in a big bang forcing Citroen to actually do something...

The car's YET ANOTHER on ebay - this one's only covered a modest 64k miles too! Do other non Cit cars' suspensions fail this badly!?

Andrew

I'm sure all us Xantia owners would like Citroen to replace strut tops FOC, but what are the chances of that?

How would I find out? - an e-mail to Citroen UK perhaps? I'll give it a try and post the response.

P.S - look at the strain on that hyd pipe...eek....shows how ductile they are though.

EDIT### I'vejust sentthis to Citroen UK. (I'll see what I get back.)

"Hi,
I have a 1996 Citroen Xantia Activa and am becoming very alarmed and concerned at the current spate of suspension strut top failures I am seeing posted on the internet and through Citroen owners forums.

These cars all appear to be well maintained and hold current MOT's.

Do you consider this to be a serious safety concern? and kindly confirm the Citroen UK position in this matter and regarding these failures.

Regards,
Nigel Wirdnam."

This post has been edited by wirdy on February 24, 2007 12:31 pm

There's no doubt Citroen are aware of this failure and in a way it's a bit of a ticking bomb
waiting to go off in someone's face if there's NO widespread awareness of this failure.
Citroen should really be dutybound to issue some warning through motoring magazines/
press releases etc - there IS an awareness among VOSA testing stations although their
remit is to look and prod but not undo/dismantle which may be required to see behind
the bellows boot.

SIMPLY, IT'S A BAD AND MORE IMPORTANTLY DANGEROUS DESIGN THAT NEEDS
RECTIFICATION WITH DISCOUNTED/SUBSIDISED REPLACEMENTS FROM CITROEN

Andrew

This post has been edited by Andmcit on February 24, 2007 01:23 pm

They're no doubt very conscious of damaging the brand name by doing this.

I agree it's a design flaw on what is otherwise a very corrosion-resistant vehicle.

Yes, VOSA and the Australian agencies are well aware of this problem through inspection bulletins we've all seen, but how long before a strut-failure fatality in the UK? Would it even be reported?

I wouldn't like to be doing 70mph and hit a pothole on the A1 with a weak strut top that had passed it's VOSA inspection during the preceding 12 months

I live in a very hilly part of the world with fantastic twisty ( )
roads and sometimes ponder whether I'd even be found, lying upside
down off the bend in the big hedge somewhere for days after my "off"
as a result of a strut boing phutt. Whilst I regularly check the struts of
the many Xantiae and Xm I drive off and on, I simply can't trust them.

The only answer seems to be multiple AND expensive purchase of new
tops which cannot reasonably be £ justified!! Guess I could drive like a
boring slow paranoid git like the other 80% of the drivers round these
parts instead...

No coincidence then that I drive my CX's more than I have been in the
recent past. A sad irony then as the idea was to spare the wear and tear
on the CX by driving a newer better weather protected daily Citroen that
is practical and still fun to drive!

Andrew


<edit> Just sitting here thinking...

What's the bleeding point in having a well protected galvanised/rustfree
bodyshell when the strut's bring the lot to it's knees and make it scrap
due to excessive corrosion due to poor design with it's inadequate
strut top plate shoulder thickness...

The best way you can be green these days is to actually PROLONG the
working life of any car - not harp on about carbon footprint/offset by planting
a forest somewhere to try and make a new car manufacturer feel a bit better
in his PR department. The biggest pollution to the environment IN MAKING IT
will always outweigh the "pollution" in the subsequent life's use of it...

RANT OVER - I'LL GET OF MY SOAPBOX NOW SHALL I!?

This post has been edited by Andmcit on February 24, 2007 03:24 pm