Driver side knocking around the wheel arch

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C52011

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Tadpole
Tadpole
Joined
Jun 4, 2023
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Central Coast
Just picked up my C5 (2011) from a non Citroen workshop to have my rear brake pads/rotors replaced and asked them to check the knocking on the drivers side.
On uneven roads and when tapping the brake at low speed I hear a knock. The guy reckons the 'shocks are shot' and need replacing.
Having looked on line, they would probably replace the entire hydrative unit. Before buying these myself for a lot less I thought to ask you if it could possibly be anything else. Cheers
 
If that's a Hydractive car it doesn't have shock absorbers. You mechanic needs some education. What looks a bit like a shock is the hydraulic strut which pumps fluid into the sphere, a quite different action.

It could be something else in the suspension, rubbers, ball joints, etc.

Also worth listening for is a worn engine mount. If either top or bottom is on the way out the engine will rock - very noticeable if you brake at low speed. These mounts resist torque.

You should check it out.
 
Yes, it is a hydractive car indeed - he did mention that one ball joint needed replacing also as it was cracked with grease still in it.
The online sellers refer to 'hydraulic struts' as 'shock absorbers', so perhaps it's easier for this mechanic to use that language!?!

I will check check the engine mount at low speed - THANKS!
 
I found an eBay ad. It doesn't look like a shock absorber at all, the way it fits into the sphere base at the top end. I hope one isn't needed, as they are expensive. Get a mirror and torch and look for leaks.

When you do the slow stop test, put the bonnet up so a helper can look for engine rocking.
 
Luft Meister is Chinese despite the name. Are you game?
 
Diagnose it properly before launching the parts cannon. It's more likely a mechanical / bush issue than a suspension cylinder fault.
 
I get your point but same mechanic replaced front lower control arms and lower control arm bushes 5 months ago
 
There are still ball joints, mounts and perhaps the drop link to think about. All give more trouble than hydraulic components.
 
The drop links appear to be a common source of a knock on these. I'd also check the brake caliper, caliper bolts and the pads themselves for looseness/movement.
Did the knock start after the lower control arms were done? Something he's had out/undone may have come loose?
 
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I agree with David S - don't play the parts buying lottery. But from my experience it is probably the sway bar drop link on the side you're hearing the noise from. Easy to source and easy to replace if you have some skills.

The rear end also has sway bar drop links and a couple of years ago, in our younger C5, on a trip to Qld we noticed an occasional rattle from the right rear as we headed north, but everything was working fine. I tried a couple of times to find it. After we got home it was due for a service at Continental Cars and I had them check for the rattle. Yep, it was the right rear sway bar drop link.
 
Thanks for all your devoted time towards your suggestions guys! Much appreciated!!

I just ran the engine and by hand rocked the wheel fore- & back-wards whilst off the handbrake and noticed the upper engine mount on the driver side to have some movement which may explain the 'dull' knocking once releasing the brake at low speed.
Also the rubber square 'pad' below seemed to have a little movement.

The knocking whilst driving across a rough surface is a 'sharper' sound though.
 
Worn drop links give a light very annoying knock. Heavy knocks tend to come from one of the several things that support the wheel.

Listen carefully to the knock when you stop quickly as it may seem to come from the level of the dogbone torque fitting. If you can get an observer this movement can be obvious if it's severely worn. There is also a torque resisting mount under the engine, near the centre.

The mounts are there to oppose the torque applied by the engine to the wheels, so sudden acceleration and braking are when you would expect movements. Brakes apply more power.
 
If you suspect the drop links, disconnect them and go for a short drive over some rough bitumen, you will soon know if it is the drop links. If the sound is no longer there it will be the drop links.
 
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