Rear sphere movement

Unread post by **Dommo** » 06 Feb 2010, 20:08

Hi folks

The rear of my Xantia Activa has been up on axle stands for about 3 weeks now, and I noticed yesterday that there is quite a lot of movement in the two rear corner spheres.

I was under the impression it's like a typical shock absorber in design just with a sphere on the end, and shouldn't slop about. It's as though the shaft of the shock is slopping about in the shock body, if that makes sense.

I've no idea if that's normal though!?

Cheers.

Xaccers · Unread post by **Xaccers** » 06 Feb 2010, 20:13

Totally normal, and the reason why you have to set the suspension on high to crack the rear spheres when you go to remove them.

Unread post by **Dommo** » 06 Feb 2010, 20:18

Thank God for that, I must admit I did panic a bit when I saw so much slop in them. I hoped the slop would go when it was put on the ground but as I can't do that just yet I was very worried!

Is the shock/strut effectively held in place with an interference fit - between the trailing arm and body of the car?

Cheers.

Unread post by **CitroJim** » 06 Feb 2010, 20:19

Indeed, totally normal but scary the first time you see it though

Like a lot of things on a hydraulic Citroen really..

Dom, did your brother make you a ram bush?

Unread post by **Dommo** » 06 Feb 2010, 20:26

Yes very scary the first time you see it!

And yes he did... But it's made out of graphited PTFE. So we're not sure how long it'll last... Better than what was in it though, the balls were totally missing, it was literally the inner race and outer race bashing into eachother. Which is probably what happens to all of them!

He says he'd make me one out of polyurethane if he could get some liquid nitrogen or similar to make it verrrry cold (and machinable). If you happen to make a batch of your nylon ones I'd still like to have one

Cheers.

Unread post by **CitroJim** » 06 Feb 2010, 20:36

Your bush looked like this one then Dom...

That's how they go. Rubbish really...

Graphited PTFE should be fine

My moly filled Nylon66 ones seem to last at least a year.

My own Activa will be getting one soon as my genuine bush is pretty worn after just 10,000 miles

Unread post by **Dommo** » 06 Feb 2010, 20:39

Mine was even worse than that would you believe. It's in pieces under the car now actually

We'll see how it goes with the graphited PTFE, as it's self lubricating it should be smoother (and less knocky) than the bearing that came off!

Unread post by **CitroJim** » 06 Feb 2010, 20:40

Dommo wrote: He says he'd make me one out of polyurethane if he could get some liquid nitrogen or similar to make it verrrry cold (and machinable). If you happen to make a batch of your nylon ones I'd still like to have one

I thought about polyurethane Dom and there is a grade that can be machined after freezing in a domestic freezer. Quite how you keep it cold in a lathe though is another matter! Make 'em in the winter and leave the workshop door open I guess

I also asked one of the makers of polybushes if they would make a batch a year or so ago. Absolute zero interest or enthusiasm from them for the job as they only do seriously big batches for popular cars.

Yes, I need to make a couple soon so I'll do one for you...

Xaccers · Unread post by **Xaccers** » 06 Feb 2010, 20:41

Mine's something like that too.
Explains why the back feels rattly

Unread post by **Dommo** » 06 Feb 2010, 20:44

Well according to my brother someone he asked said you could go to a particular place in a hospital and ask for some liquid nitrogen and they'll give you some.

How much truth there is in that I'm not sure, but if anything ever comes of it I'll make sure a few bushes get made! I'll ask around for the liquid nitrogen when I'm on placement in hospital again (student radiographer, only 5 months to go until I'm qualified, yikes

)

Unread post by **CitroJim** » 06 Feb 2010, 21:25

Dommo wrote:, but if anything ever comes of it I'll make sure a few bushes get made! I'll ask around for the liquid nitrogen when I'm on placement in hospital again (student radiographer, only 5 months to go until I'm qualified, yikes )

Hey, I wonder of you could x-ray a ram to get an idea of the internal construction of one Dom

That would be incredibly valuable!

Unread post by **xantia_v6** » 06 Feb 2010, 21:55

How to get liquid Nitrogen

Pleiades · Unread post by **Pleiades** » 06 Feb 2010, 22:12

If you remember Jim, you let me have an old one of these joints to see if we could get our rubber people to make them.

The problem is that the bush is a rose joint, to make one out of ptfe, polyurathne or any other substance just will not allow the correct movement of the strut.

I could get them machined very easy and quite cheap too, but as a plain bush they just will not last.

In the future this may well be the only option and owners of Activa cars will just have to get a bag full and replace them as they wear.

Regards
Martin.

Xaccers · Unread post by **Xaccers** » 06 Feb 2010, 22:54

CitroJim wrote:
Dommo wrote: He says he'd make me one out of polyurethane if he could get some liquid nitrogen or similar to make it verrrry cold (and machinable). If you happen to make a batch of your nylon ones I'd still like to have one
I thought about polyurethane Dom and there is a grade that can be machined after freezing in a domestic freezer. Quite how you keep it cold in a lathe though is another matter! Make 'em in the winter and leave the workshop door open I guess

Wart removal spray.

Unread post by **xantia_v6** » 06 Feb 2010, 23:28

CitroJim wrote:

That's how they go. Rubbish really...

Pleiades wrote: The problem is that the bush is a rose joint, to make one out of ptfe, polyurathne or any other substance just will not allow the correct movement of the strut.

So why can't you just fit a new rose bearing? e.g. see here