When is a bush not a bush, the Activa saga part 2

[Pleiades]

Well thanks to Jim, 1 x worn bush arrived with me this morning, I have taken all relevent info and had a realy good look.

The answer is...... we are all wrong? it's not a bush at all, it's made more on the lines of a bearing.

Stripping it, there is the external sleeve, this is then fitted with 2 x nylon half cups, this is to enable the whole arrangement to twist and turn in all directions needed. The centre sleeve has a radius so that it can move freely in the bush. The rubber that hangs out from the sides is a couple of seals to stop the dirt ingress.

I still belive that a replacement would be best made as a rubber bush as this would still allow the movement needed, whereas the solid type will not.

Photo's for those interested.

[handyman]

Hello Martin, that is a rose-joint by any other name. That is nothing like the bush I removed from the rear ram of my early Mk1, prior to replacing it with my current bush system.

The fact that Citroen decided to use a woefully undersize rose-joint for this application shows somebody got their calculations wrong. As far as I can see, the bottom location of the ram rotates in two planes, not three, so why did Citroen decided on fitting a joint, instead of a bush.

I shall have a look at my other Activas to see if they are fitted with this joint.

Handyman

[Pleiades]

OOOPPPS!!!!!!!

Sorry the pictures are a bit big.

Yes Handyman, Rose joint is the word that I could not think of.

The joint works a bit like the swively type bearings that I allways used to call clock bearings as they look like an old mantle clock, the bearing can carry on working whilst the whole unit is swiveled around at all angles.

I seem to remember the Activa strut having a standard bush, maybe the price increase is due to this fancy bit?

Regards
Martin.

[handyman]

Hi Martin, even £150 is still too much for a rose-joint. Some of the suspension links I have made for motorcycles only cost between £6 to £30, are fully exposed to the elements, come from the aero industry and never wear out!

The inner bearing sleeve looks rather pitted, as if it has picked up a lot of crud, which has probably acted like grinding paste on the two polymer bearings. What are they made from?

Why didn't they use stainless steel for the inner sleeve and graphited nylon for the outer bearings? Still think the whole lot is undersize for the loads imposed on it.

I might strip down my bush conversion and post some photos for you to compare.

What does anybody else think?

Handyman

[CitroJim]

I'm well impressed with the Post Office I posted the bush late on Thursday evening Martin...

It is interesting to see what's inside.

I agree it's woefully inadequate and a well machined 2-piece bobbin made of PTFE would seem to be a far better replacement.

What's PTFE rod like to machine? The Nylon 66 I've usd in the past machines beautifully.

Now we know what is in the "bush" how good a material is nylon 66 for this thought to be? As I've said, mine lasted very well.

[handyman]

Hi Jim, PTFE turns and finishes easily enough. I'll PM you the angles needed to make up the tool bit and cutting speeds, as recommended. Might even do it later today.

The only two things to be wary of are cutting speeds to obtain a fine finish and smoking whilst turning. Apparently, if you smoke whilst turning PTFE, the fumes given off, combined with the cigarette smoke produces a lethal gas guaranteed to shorten the life of the inhaler. I AM NOT KIDDING!

Do you know which grade you are using? The Dupont site lists a whole range, but I doubt all will be available in small quantity. My stock came from a supplier as scrap so who knows what grade!

Handyman

[CitroJim]

Thanks Handyman That'll be very much appreciated!