Rear suspension cylinders

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jvbram
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Rear suspension cylinders

Post by jvbram »

Hi. Just replaced the rear suspension spheres. But when the car was supported on axle stands and the height lever on low, the cylinders were very loose and leaked. The leaks disappeared when the car was put back on the ground and the cylinders were captured again. Is that normal?

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white exec
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Re: Rear suspension cylinders

Post by white exec »

Not sure about your fluid leaks (shouldn't happen), unless the spill-back (return) pipes took a knock, or the gaiter (which collects and returns fluid) had some contents, which were let loose.

The cylinder is normally loose in its housing if the wheels are allowed to hang, which is why the rear spheres should be initially slackened by about a quarter or half a turn with the suspension set to highest, so the cylinder is clamped. If the cylinder twists, there is a risk that the steel pipe connections to the cylinder will be damaged.

Sounds as if everything is ok now.
Chris

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Re: Rear suspension cylinders

Post by jvbram »

Thanks Chris. Is there any reason why LHM return harness is so complicated if all the tubes are doing the same thing - returning fluid to the reservoir? Or is there some internal one way valves in it?

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Re: Rear suspension cylinders

Post by white exec »

So far as I know, they just all make their way back to the reservoir, often joining up with others on the way. No non-return valves. When arriving at the reservoir, they are 'open ended', so no real back-pressure, except for the smallness of the bore.
The flow along most of the return pipes is quite small, with the exception of the power steering, which has its own larger pipework, or when lowering the car from a higher setting.
Chris

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Re: Rear suspension cylinders

Post by xantia_v6 »

I believe that for components with 2 return lines (e.g. the rear cylinders) one of them is a vent line, and the action of the piston moving, in conjunction with restrictions in the gaiter result in a one-way flow of air from the vent line and LHM being pushed back to the reservoir. It is not good if the gaiter becomes totally full of LHM, as it would burst when going over a speed bump.

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Re: Rear suspension cylinders

Post by ghaddon1701 »

I recently had this problem. One cylinder to was leaking after a sphere change. I removed the cylinder completely unnecessarily as it turned out. It was just that the sphere seal was not sealing properly.

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Re: Rear suspension cylinders

Post by Jaba »

jvbram wrote:
Tue Nov 09, 2021 4:16 am
Hi. Just replaced the rear suspension spheres. But when the car was supported on axle stands and the height lever on low, the cylinders were very loose and leaked. The leaks disappeared when the car was put back on the ground and the cylinders were captured again. Is that normal?
What might of happened is that when the sphere is removed some LHM escapes and runs back on the underside of the cylinder until it comes to the end of the mounting enclosure just in front of where the gaiter attaches to the cylinder. It will stay there until the cylinder becomes loose when it will appear as a leak. Possible ?? or not.
The Joy of BX with just one Citroën BX to my name now. Will I sing Bye Bye to my GTI or will it be Till death us do part.

jvbram
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Re: Rear suspension cylinders

Post by jvbram »

Good suggestion but in my case the fluid came from the gaiter. I dont understand french engineering. What possible advantage can a loose piston be? The fact that the front piston are not loose indicates no advantage.