C5 Suspension Retro-fit

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rossnunn
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Post by rossnunn »

Ok I've given this plenty of thought & while I do still believe its viable I need to get my mitts on key conponents - theres only so much reading/exploded diagrams one can do.

I believe c5 is the best option.

Looking at room around the car I do think there's room for all the bits & pieces.

The front legs I as looking at (Im assuming they are not inserts) using custom make top mounts to convert into the factory towers or possibly 406 jobbies.
Remote mounting the sphere blocks.
Look into using Xsara front hubs, as they use a upwards facing lower arm ball joint as per the 106, using custom droplinks that would only leave the steering joint, that as has already posted sits waay higher on the 106. I dont really like the idea if weilding directly to the strut body so would need some thought.

I have taken a look at the height correctors & they look like they just clamp to the factory arb - which could be just bolted directly on the 106's own.

The diagrams also describe the c5's rear suspension as torsion bar, thought the rear arms look to bolt directly to the crossmember, where as the 106's uses a 'normal' torsion bar setup with the bars holding on the rear swing arms. I had intended to keep these in play.
The 106's ARB is inside the tube but a small 'window' could be cut into this to allow the height corrector to be bolted to it.

That would leave the fitment of the rear c5 suspension units - they look mighty tricky & I've not looked into the fitment of c5 rear swing arms although I suspect they are miles to big.
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Post by cachaciero »

The C5 rear suspension is NOT torsion bar it is "swinging arm" same as Xantia. The C5 pump requires connecting to a CAN bus and it is coded i.e it checks the VIN number from the BSI and compares it with it's own coded VIN number no match no go.

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Post by rossnunn »

mmm thats what I thought, that would need some serious thought & probably some trial & error.

The pump is a issue, but not as much as the ECU will be.
Are all C5's multiplexed? even ph1's?

Also I may have come up with a idea about the struts, however could someone please explain the interaction between the Hydractive system & the actual strut?
From what I can see there is no fluid transfer at the top mount/sphere block & the top of the strut, in fact the only part I can see is the fluid return pipe, towards to bottom of the strut body.
So does this control the amount of LHM doing into & out of the leg? & thats how it adjusts ride height, by pumping in/removing fluid in at this point? or is it just a return pipe?

Cheers
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Post by cachaciero »

talking C5 there is no return line as such just a common line from the BHI (Pump unit) to both the cylinder.s on each axle.
Within the BHI there are two valves for each axle one valve is from the pressure side of the pump to the common line the other valve connects the common line to the resevoir, open one valve system rises, open the other system lowers.

The H3 and H3+ systems work at this level identically ,the H3+ has the additional sphere and regulator connected between the two suspension units on each axle it opens or closes by means of a solenoid valve also controlled by the BHI.

Yes all C5's are multiplexed only difference is that some functionality on S1 is on VAN bus but engine suspension gearbox and ESP are on CAN Bus. S2 it's all on CAN bus (buses).

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Post by rossnunn »

right, if we leave aside the multiplexing for a sec.

so the only fluid transfer betweem the actual strut body & the rest of the system is via the single pipe going into the lower part of the shocker?

if this is true, what stops one taking a factory set of dampers for the 106. Drilling a hole & draining the oil out, cut a hole, or whatever, in the shocker body to match that in a c5 strut & mounting the pipe assemberly to the 106 shocker? The rears could them use remote mounted sphere's using a second set of sphere block remote monted under the floor.

this would overcome all the fitment issues for the front & rear legs (the torsion bars could remain, but some brackets weilded chassis rail to pickup the rear torsion bar mount on each arm, to convert them into a sedo swing arm affair.) The front springs would need to come out of course but the spheres would replace them (in use not position)

the only issues I could see with this was the seals in the actual shocker breaking down due to the lhm or not being able to handle the pressure??
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Post by Chris570 »

rossnunn wrote:right, if we leave aside the multiplexing for a sec.

so the only fluid transfer betweem the actual strut body & the rest of the system is via the single pipe going into the lower part of the shocker?

if this is true, what stops one taking a factory set of dampers for the 106. Drilling a hole & draining the oil out, cut a hole, or whatever, in the shocker body to match that in a c5 strut & mounting the pipe assemberly to the 106 shocker? The rears could them use remote mounted sphere's using a second set of sphere block remote monted under the floor.

this would overcome all the fitment issues for the front & rear legs (the torsion bars could remain, but some brackets weilded chassis rail to pickup the rear torsion bar mount on each arm, to convert them into a sedo swing arm affair.) The front springs would need to come out of course but the spheres would replace them (in use not position)

the only issues I could see with this was the seals in the actual shocker breaking down due to the lhm or not being able to handle the pressure??
Sorry but there is no way that would work for more than 0.3 seconds. The pistons in the Hydraulic citroens are machined very very tightly and standard shock absorbers simply arent machined for this purpose. So in theory the principle would work in practice it wouldnt.

Without going into too much detail i've done a lot of research into this and Xantia is the best way to go. The C5 is a lot of hassle to retrofit when all you're really gaining is electronic height correctors and pump, but with that you get all the hassle that comes with it.

Look not at how the system is laid out but what it actually does, has to do, how it does it and why it does it. There are other ways of piping it all up (read laying the system out) that means you can do all sorts of fun things in regards to item placement. These are all things that will be documented in a build i'm running at the mo.

The Xantia's are fed from the top down so the only rubber part is a return pipe under sod all pressure.

You want to avoid feeding high pressure fluid into the bottom end of the suspension due to the amount it moves and well, makes sense really.
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Post by addo »

You can still use an electric pump and remote spheres - it worked for the 405.

To expand on Chris's comments about the struts, Citroën oil seals are mostly teflon rings with an o-ring physically underneath them.
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Post by rossnunn »

right ok I'm sold on the Xantia - its good for me as I have a LX in the garden.

However, I was looking for a fairly........not simple or easy or even straight-forward, but........more of a bolt-on solution, however the 2 key components in the build - front & rear struts are different enough not to facilitate this.
405 items dont even look close either & TBH the chances of finding one (we used to own a 405x4 with it! lol) is less than finding a activa in the breakers!

So basically, although I love the idea & have faith it could/would work - without serious financial inverstment, its a dead duck. :(

Thanks for all your help guys, fantastic as always 8-)
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Post by rossnunn »

I guys,

Quick couple of questions;

Would a standard shock take the pressure of the Xantia system or would it just blow the internal seals? (I suspect the seals would blow as soon as any decent size bump is run over)
Also would the system work (or is there) another oil than could replace the LHM & enable me to keep the factory shocker bodys & tap the lower part of them into be used with a remoted fitted sphere?
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Post by Geoff Lebowski »

I\'ve not read every detail here but my initial thoughts are that:
you may struggle or incurr a lot of cost in getting the correct sphere damping and pressures for such a light car. Not saying you won\'t do it, just that it\'ll be a trial and error process.

Using a BX setup would be simpler but of course not hydractive. You can also start with the most basic BX sphere spec (for the 1.1 or 1.4) and go from there. Raising sphere pressure will make it softer.

Good luck.

p.s. It may also be worth exploring the C15 as I believe they had spheres (at least on the rear) all be it not height adjustable (again - I believe). The C15 is more 106 sized
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Post by Citroenmad »

Geoff Lebowski wrote: p.s. It may also be worth exploring the C15 as I believe they had spheres (at least on the rear) all be it not height adjustable (again - I believe). The C15 is more 106 sized
The C15 never had hydraulic suspension so does not have spheres. There was one made years ago to have it on the rear, I think a BX rear beam was used.

Seems quite a challange to me, will it be worth it?
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Post by Geoff Lebowski »

Really? I\'m sure I recall someone on another forum suggesting using the C15 as a trailer axle for - I assume - a sublime trailer ride. Anyhoos, will it be worth it? I doubt it, but I never like to stand in the way of people having a go, after all, even if it ends up a failure, the chap will of learnt a lot along the way.

Anyway, thanks to you mr Citroen Mad Man I am today collecting a 2001 C5 Estate 2.0 HDi 110 SX!
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Post by dnsey »

An interesting 'thought experiment', but before putting it into practice, I'd suggest having a word with your insurers :shock:
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Post by Citroenmad »

A C15 rear axle might well give a trailer a good ride but it dont be hydraulic. Just imagine the complexity in having a trailer on spheres :lol: You would need some way of powering the pump, and thats only the first problem.

Nope, Citroen never had a production run of hydraulic C15s, shame really. That would have gone very nicely with our 6 wheeld version!


Thats excellent news Geoff, possibly the best spec and engine to go for in terms of reliability. I hope you enjoy it :)
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Post by Geoff Lebowski »

Thanks CM, she\'s not bad in all. I\'ll start a new thread, possibly a dreaded blog to voice my observations and queries. Overall a very good purchase so thank you to you and Paul for your suggestions which helped me get the best option for me and family
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