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Suspension difference left vs right on front axle ?
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JerryCitro   
Wed Aug 09 2023, 09:34pm
Joined: Mar 03 2021
Member No: #4638
Location: Basel
 Hi, I am new on this forum as a C6 driver with the first "malfunctioning" of my 2.7 HDi Exclusive (from Aug 2008) since I drove it for about 2 years, 6t km without any problems, mainly long motorway trips after I had bought the C6 with 210t km. Then it was fully serviced, had a new waterpump, thermostat, chain/belt etc. (you name it) revision and had passed the Swiss MOT (MFK).

In May this year my C6 didn't pass the Swiss MOT, reason: the shock absorber test showed a difference of 43% at the front axle between left and right, the left being the stiff side. (see picture 1) While driving I couldn't feel a big difference between left or right, although I always had the impression that the right side moved slightly more up and down. With ignition on, the car raised normal. It did go up and down as normal, when pressing the respective buttons. The "sport" mode functioned nicely, bringing the car almost to that magic carpet feeling (I experienced in my past CX Break 25 TGI). Never experienced any malfunction alert on the suspension.
Thus that 43% difference was quite a surprise.

My mechanic changed the 2 front spheres. No success.
Car height control/calibration was OK. No success.
Then finally the left Amvar shock absorber/cylinder was replaced, after all suspension bearings, rods, levers, etc. were found to be OK.
I noticed a suspension improvement while driving, overall it gave me the impression that the car was even more smoother and more keeping steady horizontally.
At the same shock absorber test, there was still a 29% difference (see picture 2).

How can this be interpreted? What could be considered further to undertake?
From my mechanic I understand that Lexia/Diagbox cannot give further guidance.
Software update possible of AMVAR?
Your comments, suggestions are welcome.
Jeroen
onthecut   
Thu Aug 10 2023, 07:00am
Joined: Sep 20 2016
Member No: #2793
Location: West Mids
 Hi Jeroen.

First thing I would try is to swap over the left and right hand sphere and see if the problem moves with the sphere or stays on the same side. I appreciate you say that your mechanic has changed the spheres, but you can't take for granted that the replacements are what they should be. I have bought new spheres in the past and had completely the wrong specification in the box, compared to the label.

Check also they are C6 struts. The C5 ones from the same period are a different part number, as I recall.

Next I would do the basic bleeding procedure a couple of times, which as far as I can see is full height down to low setting; leave a feew minutes and repeat.
If you do this, check you don't have too much fluid in the reservoir as it is likely to push it out on the low setting.

Check the electrical connections at the strut top and at the control unit by the pump.

Mike.
cruiserphil   
Thu Aug 10 2023, 02:22pm

Joined: Jan 24 2010
Member No: #38
Location: Celbridge
 Hello Jeroen,

As per Mike (onthecut) and also your right hand strut maybe faulty (worn). The AMVAR servo motor on the top of the strut performs the damping function. The basic soft/firm damping functions can be tested per individual strut with Diagbox. It may show if one of the AMVAR units is stuck.
If your checks don't improve anything you will probably have to change the other strut.

Best regards,

Phil C.
JerryCitro   
Tue Aug 15 2023, 01:42pm
Joined: Mar 03 2021
Member No: #4638
Location: Basel
 Hi Mike and Phil,
Many thanks for your replies and good suggestions for next step checks.
I will give feedback as soon as my C6 goes for MOT again by end of August.
Thanks, Jeroen
Kaloteck   
Wed Dec 27 2023, 03:17pm
Joined: Apr 25 2013
Member No: #1271
Location: Warsaw
JerryCitro wrote ...

The "sport" mode functioned nicely, bringing the car almost to that magic carpet feeling (I experienced in my past CX Break 25 TGI).

You mean the "normal" mode?
Because the "sport" mode does quite the opposite.
 

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