Adjusting ride height on normal suspension setting

[Jugostran]

Hey there,
I have been reading through some old threads regarding this topic, and found out that my BX rides a bit too high on its normal suspension setting. I did the "four finger test" (gap between tire and wheel arch), and concluded that it rides 3-5 cm too high. The rear also raises slightly after coming to a stop, and the front drops about 3-5 cm immediately after shutting it off. Now, I have seen some discussion regarding what the best way is to adjust the suspension, but I haven't managed to track down any mention of what exactly needs to be adjusted in order to change ride height. If anyone knows, I'd greatly appreciate it!
Cheers!

[Fumbler]

The rear raising when coming to a stop is completely normal. When braking, all hydraulic effort is directed to the brakes, so pressure will release in the suspension.
The height correctors operate via a linkage which connects to the anti-roll bars. To adjust, get the car on a 4-post lift, never on the ground slacken the bolt on the linkage clamp just enough so the clamp moves with the tap of the hammer. When you move the clamp, the linkages will move, and the front will rise or fall depending on the direction it turns.
This is a bit of a general overview as I recently went and had a specialist adjust the height and allowed me to see how it worked. I mightn't be completely correct.

[Jaba]

I learnt how to adjust the height linkages from Haynes so if you don't have a copy this would be a good acquisition to help you understand the process. I never measure the actual height in mms as the 4 finger test is good enough and adjust the rear end after the front and get the sills parallel to the ground. Its important to have the correct linkage gaps for the HC operating arm at the front and rear.

Its not difficult to do but be prepared to do it safely and to not get it right the first few attempts.

[white exec]

Rear raising when braking is normally a sign that there is air trapped in the rear suspension/brakes. This readily compresses when the brakes are applied, but expands again when the brakes are eased off, which can cause the rear end to rise.

Excessively fierce rear brakes (rare on hydraulic Citroens, with their small rear discs and pads) would cause the rear end to squat when brakes were applied.
One of the great things about our fluid suspension is that the car is designed to ride level under all normal conditions.
An emergency stop might cause a small amount of front end dive, but this should be minimal.

[Kaapelimies]

Rear raising when braking is normally a sign that there is air trapped in the rear suspension/brakes. This readily compresses when the brakes are applied, but expands again when the brakes are eased off, which can cause the rear end to rise.

Yes. And to get rid of this, bleed the rear brakes. Engine running, rear wheels on ground, install brake assistant (here we have snow brush or small shovel, to push the brake pedal) and loose a little the nipple in the saddle. There will be a lot of pressure and air bubbles so hold a rag over it not to make a mess. If you don't have alloys of teenage-driver model, then this trick won't work as you need to remove the wheel to get access .

[white exec]

This is the official way to bleed the braking system...
.

Source: Citroen 'Private Cars' booklet, 1992 CAR050920 p.202 (AX, ZX, BX, XM)

[Defender110]

Rear raising when braking is normally a sign that there is air trapped in the rear suspension/brakes.

It's often gas in the system on a BX from leaking spheres too, certainly not normal behaviour and should be cured like you said by bleeding the brakes and replacing spheres if required.

[Jugostran]

Thank you all for the excellent advice!
I will probably take my car to a specialist (provided I track one down) as there are lots of issues to adress in addition to the incorrect ride height (leaking pressure regulator, squeaky brakes and a leaky LHM reservoir).

[Jugostran]

Rear raising when braking is normally a sign that there is air trapped in the rear suspension/brakes. This readily compresses when the brakes are applied, but expands again when the brakes are eased off, which can cause the rear end to rise.

Yes. And to get rid of this, bleed the rear brakes. Engine running, rear wheels on ground, install brake assistant (here we have snow brush or small shovel, to push the brake pedal) and loose a little the nipple in the saddle. There will be a lot of pressure and air bubbles so hold a rag over it not to make a mess. If you don't have alloys of teenage-driver model, then this trick won't work as you need to remove the wheel to get access .

I have 1989 architect-spec that has standard hubcaps with steelies (though the hubcaps have long since biodegraded and liberated themselves from the car), so accessing the brakes is quite a chore.

[white exec]

Put car on highest, jack up a tad further and support, remove wheels, and bleed as described.

[Jaba]

Leaking LHM reservoir: is this from the underneath if so it will have rusted through. The rust holes can be repaired with ingenuity but sourcing a replacement is easier.