spheres are they the same?

jet_black · Post by **jet_black** » Tue Sep 22, 2009 10:12 am

i am about to change the spheres on my BX i have 2 that i bought some years ago for a Xantia that unfortunately died but i am not sure if they are interchangeable. My intention is to change the whole lot so i was needing to know if all the spheres are the same E.G are the ones on the rear different to the fronts, is the regulator sphere different etc

MULLEY · Post by **MULLEY** » Tue Sep 22, 2009 12:53 pm

They are all different, even within the bx range there are different one's for the different models, front & rears are different as well. The only one thats the same (i think) is the accumulator sphere. Some members have fitted xantia & xm spheres instead of the bx accumulator, not sure about the other spheres.

Also, when i mean different, there is very little difference in the size of the bx sphere, quite often they are identical, however the internals are different so that you have changes in volume & damper rates etc...

I'm sure there is something already on the site about this, either try the diy section or use the search function to see if you can find out more.

DLM · Post by **DLM** » Tue Sep 22, 2009 1:37 pm

Accumulator spheres are more or less universal. Fronts and rears are not normally interchangeable - check with an application table like these:

http://www.tramontana.co.hu/citroen/sus ... ension.php

http://bx16valve.co.uk/Files/spheres.pdf

If that's confusing then just post here the model of BX and Xantia you have, including whether they're estate or hatchback.

What's most important (apart from the basic condition of the spheres themselves) are

(i) Volume e.g. 400 or 500cc (round/lozenge)
(ii) Pressure e.g. 55Bar - impossible to tell unless stamped on sphere
(iii) Bore - e.g. 1.65 - impossible to tell unless stamped on sphere

They should be matched pairs of suspension spheres - swapping-in single suspension spheres is not a good idea. All 3 values above are important - the last (bore) roughly tells you how hard or soft the ride will be.

They must also be pure suspension spheres - don't fit suspension spheres from a Hydractive Cit onto a BX as the bore sizes are very small.

Xantia centre spheres, or stay-up spheres are also not suitable for use on a BX - they're not suspension spheres (no bore?).

kiwi · Post by **kiwi** » Tue Sep 22, 2009 8:15 pm

DLM wrote:the last (bore) roughly tells you how hard or soft the ride will be.

Now thats interesting.

I have been thinking for a while now that the 19TZS I have has much firmer spheres and handling than its cousin the 19TRS.

Knowing its previous owner worked for

I am thinking he fitted a differant bore size sphere set.

So which would be firmer 1.65mm or 1.8mm Bore?

Brian · Post by **Brian** » Tue Sep 22, 2009 10:54 pm

So which would be firmer 1.65mm or 1.8mm Bore?

The larger the damper hole, the quicker the LHM will pass through it, so it's softer.

Try fitting accumulator spheres "These have no damper discs" then give the car the bump test !!!...

Do not drive the car on the road though.