Suspension dropping over time

[Gouldy]

Hi guys as some of you may have read I have a bouncy back end on the gti and overnight it seems to fall.

Once started it picks up height again within ten seconds but wondering if this is another symptom of a failed pair of spheres?

[RobC]

This is perfectly normal behaviour. The car always sinks- usually rear first (which is why Citroen introduced ‘anti sink’ spheres in later models because people thought there was something wrong with their car.)
Your bouncy rear will be worn spheres and/or rear arm bearings.

[white exec]

Anti-sink is quite a complicated addition of a multiway anti-sink valve front and rear, a good bit of extra pipework, and one additional sphere. I have it on our S2 XM. Not really worth considering for a BX, I would think.

Sinking could be thought of as a small contribution to "anti-theft", I guess.

[Gouldy]

Thanks guys, new spheres it is then as it’s bouncy too

[Dave_16v]

Ensure the correct spec. is fitted, 400/40/1.10, any softer and the acceleration of a Gti will may cause the rear to dive and it will feel too soft anyway.

[Gouldy]

Have given the place the reg so should get the right ones.

Never done them before so any links to a how to would be epic

[rutter123]

The Haynes bol gives a pretty good description, it helps if u can get the back end up on some ramps for better access, you need to remove the old spheres carefully, first you will need to crack the spheres off about quarter to half a turn
whilst the system is under pressure and the lever in high-this stops the cylinder from turning in the housing and prevents pipes getting damaged.
Use a suitable tool to grip the circumference of the sphere, pipe grips, chain type oil filter wrench, or a ratchet strap as you will need some leverage, don't hit it with a hammer, some can be kin tight, slowly but steadily start to unscrew it until its just cracked off, don't force it as pipe damage can happen
Then depressurise the system by putting lever in low and let the car settle right down, you can then slowly unscrew the sphere, if you hear pressure release something is wrong. Slowly unscrew by hand a bit of fluid may come out.
Screw new ones hand tight making sure the new seals are correctly seated. Then repressurise the system with lever in mid position until the back rises and settles, you can now tighten the spheres up a little more, run a couple of full ups and downs to bleed the system, check for leaks, top up lhm.
That's how I do mine
With caution, safety first n all that
Never work on any part of the hydraulic system when it's under pressure unless u want to turn green.

[xantia_v6]

Have given the place the reg so should get the right ones.

I would be wary of registration lookup on a car as old as a BX, as there were no online databases with detailed build specifications when the car was built, and even Citroen don't always have full spec data for cars built 30 years ago.

[Gouldy]

Ok mate thanks!

[Kitch]

Have given the place the reg so should get the right ones.

I would be wary of registration lookup on a car as old as a BX, as there were no online databases with detailed build specifications when the car was built, and even Citroen don't always have full spec data for cars built 30 years ago.

Yep, what he said. I'd hunt the part number down yourself, personally.

[white exec]

The Citroen Mechanic's handbooks properly list the full sphere spec (eg 400/40/1.10) for every model. Several of these booklets cover the BX, and all are downloadable from the Members' Resources section on FCF.

It's the last (damping) figure that rarely gets listed by the aftermarket sellers, and you just have to take that important characteristic on trust. Even Citroen Parts (Servicebox) only lists cc/bars, and not the damping figure.

Agree about using reg.no. being risky, especially on older vehicles.