Sphere mount bracket

[xmexclusive]

Hi Steve

I have aquired sample bits of all types, only missing an Xantia strut.
The recent discovery that the strut head rubber has directionally based varying resilliance has come as a bit of a surprise.
This could well prevent using one of the alternatives because of the different sphere position with each design.
Rotate another type of strut head to get the sphere in the XM's sphere gap and you may significantly alter the strut steering stability function.
I had not expected the C5 strut head to be so different to the others.

John

[steelcityuk]

Right John I see, so it was a silly question.

Steve.

[xmexclusive]

Hi Steve

With the strut heads there are quite a few problems to identify and then consider if they can practically or economically be overcome.
That does not make any questions raised either silly or unhelpful.
I find the range of ideas and questions raised on these forums both very helpful and positive in understanding and solving the technical problems of XM ownership. Sometimes it also takes a bit of repetition for me to pick up one the importance of some of the technical detail.
Noz has suggested forced rotation of the strut head to change the hand of XM and Xantia ones.
Sectioning the centre of a head or practical tests may prove if this is possible without loss of structural integrity.
My detailed measuring up of the various types of head and struts will show what interchangability there is between designs.
So keep the qustions and your information input coming as it all heps us all.

John

[xmexclusive]

Hi Steve and All

Following the prompt above I could not resist spending an hour or so checking out the collection of strut components.
Tried a few rough comparisions against one of the SORN XM's.
My assessment is:
C5 Strut
The strut has an identical base fixing point and is a tight fit when offered into an XM wheel hub.
The LHM leak off return is identical to the XM.
The suspension drop link strut fixing is totally different to the XM. Vertical bracket with lateral hole.
The taper on the top of the strut rod is different in diameter and angle.
That makes at least 4 different strut rod tapers that Citroen have used.
C5 Strut Head
The two that I have are from a 7 year old 250k miles HDi with a blown engine. It had been used as a Taxi.
The strut heads had a little surface rust and no sign of rubber deteriation.
On this evidence they will outlast the cars. The two are identical and not handed.
The metal centre core is manufactured in the same way as XM and Xantia cores.
So if Noz's suggested rotation works for XM cores it should also work for C5 ones.
The dimension from Hydraulic connection to strut head base is roughly 30 mm greater than the XM dimension.
This is an idea dimension for a fabricated steel converter plate to fit a C5 strut to an XM.
I could not check if the C5 strut head was too large or odd shaped to fit through the XM chassis hole.
First impression is that it will just fit.
So where does this get us:
I think it is well worth progressing with a bit more research on all the options.
Option 1 - C5 Strut and Strut Head
Drop link needs sorting unless the C5 one fits.
Converter plate needs designing and fabricating.
Strut and Strut head match.
Sphere positon needs resolving - rotate head or modify pipework/chassis for C5 fore and aft mounting.
Option 2 - C5 Strut Head and XM Strut.
A late XM thick strut rod has enough meat to machine the taper to suit a C5 strut head.
As an alternative it might be possible to ream out the strut head.
Standard XM drop link can be retained.
Converter plate needs designing and fabricating. (Same design as Option 1).
Sphere position needs resolving. (As Option 1).

John

[steelcityuk]

That's a good bit of research there.

Option 1 sounds more viable to me.

Nice work John.

Steve.

[xmexclusive]

Hi Steve

The downside that I see to option 1 is the need to obtain the C5 strut as well as the strut head.
At the moment new C5 heads are a reasonable price from Citroen. New struts are another matter.
The same will happen with secondhand. Struts tend to be priced much higher than heads.
I will have to look up the strut design parameters, particularly piston diameter.
Hopefully the C5 will be the same as XM ones.
Over the weekend I will try to run a set of calipers over the various strut rod tops.
Documenting those differences could guide the selection of methods by which compatibility could be achieved.
The difference between C5 and large XM looked to be so small that the oilway groove may not need deepening.
I will also section the metal top of the Xantia one that I investigated the rubber on.
This should provide an insight into the chances of success with brute force rotation of the head centre metal parts.
If the 10 retaining indents are swaged into a circular channel then it might well be possible perhaps without loss of joint strength.
If each of them has its own circular recess then rotation will break the joint.

John

[davetherave]

Seems hopefull!
I would certainly have more confidence in it than a remoulded xm one.
Although dont the C5 struts have a shorter range of movement?

[xmexclusive]

Hi Dave

No it is just the rubber gaiter that is much shorter.
Just happened to make some comparative checks on the struts this evening.
C5 - rod projection closed 50 mm, fully open 230 mm.
Mk2 XM - rod projection closed 75 mm, fully open 212 mm.
Mk1 XM - was different yet again, it has some type of internal spring that stopped me measuring the closed position.
Fully open was around 190 mm.
Will post again with tonights full findings.

John

[xmexclusive]

Hi All

Have now sectioned a segment out of the top part of the metal centre.
There is a "D" shaped recess (12mm wide and 3.5mm deep) running right round the top part of the metal centre head.
So Noz's suggestion of brute force rotation to reposition is possible as far as that is concerned.
Would need to be very careful how the head was forced round as it is a casting and the metal can suffer brittle fracture.
I know because to section it I made two parallel cuts with my disc cutter then broke the section out using a hammer and chisel.
I also tried to measure up the strut rods.
Strut rod diameter was 23mm on all struts except the late Mk2 XM at 25mm.
I suspect that the Xantia one is also 23mm and did a rough check by trying a Xantia head on a Mk1 XM strut.
The fit seemed good enough to get an oil seal with the right amount of thread projecting for the nut to fit correctly.
The total taper length was the same on all three types that I had available.
Top hole diameter in the strut heads was interesting.
Xantia 17mm, Early XM 17mm, Late XM 19.5mm, C5 18mm.
I then tried a C5 strut head on an early XM strut, taper seemed an oiltight fit but the unthreaded part of the strut rod projected just beyond the top face of the strut head. A suitable size washer would pull this up tight.
Strut Head top to Chassis plate on the XM strut head was approx 105mm.
The Xantia and C5 dimension was approx 150mm.
The C5 strut head has its rubber correctly positioned to replace the Xantia strut head, only the XM one needs rotation.
Think there is just a possibility of using on an Xantia just by redrilling the chassis mount holes.
A reasonable nights progress.
Edit Note: When I got an XM and C5 strut laid out along side each other on the bench there was a noticable difference in the marks from the base clamps. When I checked this is caused by a basic design difference. The clamp depth on an XM is around 75mm while on the C5 it is around 50 mm. The strut outer cases enlarge at the top of the clamp area determining how deep into the clap the strut goes.
This means that putting a C5 strut into the clamp on an XM will put the strut 25mm higher than an XM one.
Must take another batch of photos and start pulling this together as a documented record.

John

[robert_e_smart]

Great Progress John,

I look forward to any further developments.

Robert