C5 exclusive estate. Ride height.

[maximus2]

Hi.
I've been having trouble with my car. The rear collapsed in France while being driven. Was temporarily repaired finally got it fully repaired in England. Whilst sitting on drive Rear has collapsed again. I am going to have a go at it tomorrow with full safety requirements. To be able to get it back to garage I need to raise the rear. I hope it's down to rear sensor. But, what I really need is the height from ground to centre of wheel arch to get an approximate height. I understand it may be about 70cm? To have the front height maybe useful also.
It's a 2007 exclusive estate on 215 55 16s.
I have searched but cannot find an answer for my car. I will have car fully supported.
Very grateful for any replies. Many thanks.

I should add that today I started the car up and put ride height to max. As usual the front rose, but, after a number of minutes the rear suddenly rose as well! I heard a noise which turned out to be 'dog bone' link to height sensor which was on floor having detached from both ends. Anyhow, reattached it but C5 is now on its bottom and I cannot get it to move!
Ps. Dog bone is new.

[Hell Razor5543]

First, make absolutely sure the car is properly supported (so that she does not drop down on you)! You will need a tape measure. First, measure from the centre of the wheel down to the ground. Now measure from the flat surface just rearward of the rear strut sphere down to the ground. Based on the instructions Marc sent me (and allowing for the fact my C5 estate is a 2004 Mk1 and yours is a 2007 Mk2, but that are similar) the surface should be 73mm higher than the centre of the wheel. I hope this helps.

[GiveMeABreak]

Your height sensor may be kaput as opposed to the connecting rod - they can degrade if the internals are exposed to water, so may be giving out false data signals to the suspension ECU. Reading the sensor data or condition via Lexia / Diagbox will let you know the reason and to undertake the actuation tests to confirm. If the readings are well out then the sensor is probably duff. I've had both mine on the new X7 changed last year due to failure of suspension to raise intermittently, which also put the directional lighting into normal dead ahead backup mode as a result. Changed these and all is good in the world again.

[maximus2]

Thank you Mr Razor!
I shall check that tomorrow. After a few hours of the car today I have got it working again I have set it to wheel arch height 70 centimetres from the ground on normal setting. I just wish I was younger, unfortunately, I just do not have much confidence in garages, or many tradesmen in general. There are of course many exceptions, just that I come into contact with them rarely. I myself was a tradesman, but the skill levels of most people I worked with were severely lacking.
Just relieved that it's working atm. I shall live in hope. I was thinking of getting rid of it but it's a good car, spent a couple of grand on it in last couple of years (radius arms cambelt eolys and servicing etc) it would feel like a shame.
Once again thanks.

[maximus2]

Your height sensor may be kaput as opposed to the connecting rod - they can degrade if the internals are exposed to water, so may be giving out false data signals to the suspension ECU. Reading the sensor data or condition via Lexia / Diagbox will let you know the reason and to undertake the actuation tests to confirm. If the readings are well out then the sensor is probably duff. I've had both mine on the new X7 changed last year due to failure of suspension to raise intermittently, which also put the directional lighting into normal dead ahead backup mode as a result. Changed these and all is good in the world again.

Thank you Marc.
The sensor is new, it was replaced when I got back to UK. I am hoping that the problem may have been the position that the dogbone was connected to the sensor, difficult to say but it may have been connected at 9 o clock, I've connected it at 6 o clock. I noticed at 9 o clock there was movement due to angle. I presume that you are the Marc that Razor was talking about. If so does 70cm sound about right to wheel arch?
Once again thanks very much.

[Hell Razor5543]

After a few hours of the car today I have got it working again I have set it to wheel arch height 70 centimetres from the ground on normal setting.

70cm! That is nearly 3/4 meter high ! I do hope that was a typo, and you meant 70mm.

[GiveMeABreak]

Did you recalibrate the height settings last time when you fitted it? - this is supposed to be checked / done when replacing them. In case not here is the fitting guide fro the REAR sensor and the Measurement procedure follows:

Fitting Guide for Rear:

Removing:
Disconnect the connector (5).
Disconnect the rod (6), as "d".
Peg the height sensor at " e" using a 4 mm diameter rod.
Remove:
The (7) bolt
The height sensor (8)

Refitting:
Refit the height sensor ( 8).
Refit bolt (7), Tighten to 0,4 ± 0,1 daN.m.

Remove the setting rod from the height sensor.

Connect the connecting rod ( 6), as "d".
Reconnect the connector (5).
Check the heights of the vehicle (see the relevant operation).

Height Check C5 MK II (Facelift 2004 to 2007):

Official Tools - but you can improvise:

Measuring the heights

Wheel Radius Measurement

• Place tool [ 1] over the wheel screw heads to determine the wheel centre.
• Measure radius R1 with tool [2] (between the wheel centre and the ground).

Measuring the Front Height H1M

The front height H1M is measured between the ground and the subframe, at the rear of the suspension arm front fixing yokes.

Calculating the front height H1C

H1C = R1 - 140 mm .
R1 = Front wheel radius ( mm).
Compare:
The value measured H1M
The value calculated H1C
Adjust the front height if necessary.

Measuring the Rear Height H2M

The rear height H2M is measured between the ground and the zone "a" on the crossmember.

Calculating the rear height H2C

H2C = R2 + 68 mm .
R2 = Rear wheel radius ( mm).
Compare:
The value measured H2M
The value calculated H2C
Adjust the rear height if necessary.

Adjustment using a diagnostic tool
This adjustment is done when the heights measured are within the tolerance of the calculated heights.

Mechanical pre-adjustment
This adjustment is done when the heights measured are not within the tolerance of the heights calculated (± 10 mm).

Front height

• Loosen by one turn the screw ( 1) on the collar (2).
• Re tighten the screw by hand.
• To decrease the height, turn the collar ( 2) towards the front of the vehicle.
• To increase the height, turn the collar ( 2) towards the rear of the vehicle.
• Repeat the operation until the calculated dimension H1C is obtained (± 10 mm).
• Tighten the bolt (1) to 0,6 daN.m.
• Perform the adjustment with tool [ 3] or with tool [4].

• Loosen by one turn the screw ( 3) on the collar (4).
• Retighten the screw by hand.
• To decrease the height, turn the collar ( 4) towards the rear of the vehicle.
• To increase the height, turn the collar ( 4) towards the front of the vehicle.
• Repeat the operation until the calculated dimension H2C is obtained (± 10 mm).
• Tighten the bolt (3) to 0,6 daN.m.
• Perform the adjustment with tool [ 3] or with tool [4].

Adjusting the heights using tools [3] or [4]

• Connect Lexia / Diagbox to the vehicle’s diagnostic socket.
• Go into the menu:
• Access Suspension ECU / Manual Configuration / Adjust Reference Heights

N.B. : H1M = Front measured height (mm).

• Calculate 280 - (R1-H1M) for the front.
• Re-enter this value in the diagnostic tool.

N.B. : H2M = Rear measured height ( mm).

• Calculate (H2M-R2) for the rear.
• Re-enter this value in the diagnostic tool.
• Wait for the correction of the vehicle’s height.
• Measure the front height H1M.
• Check that: H1M = H1C ± 2 mm.
• Measure the rear height H2M.
• Check that: H2M = H2C ± 2 mm.

[Hell Razor5543]

OK, so the later C5 Mk2 (otherwise known as the facelift) is riding 5mm lower than the Mk1 (68mm as opposed to 73mm).

[maximus2]

After a few hours of the car today I have got it working again I have set it to wheel arch height 70 centimetres from the ground on normal setting.

70cm! That is nearly 3/4 meter high ! I do hope that was a typo, and you meant 70mm.

That's the measurement from ground to top of wheel arch!
At the time that's all I had to go on.

[Hell Razor5543]

Ah, OK.

[maximus2]

Thank you Marc I shall check measurement in the morning. The reason the rear collapses is making me wonder. The only reason that occurs to me is that the bar to which the adjustment clamp ( other end of dogbone to the sensor) is being moved or twisted in someway, therefore affecting the sensor. When I was doing it today clamp and sensor were well fixed. Have you or anyone heard of this? I should say I had the radius arms replaced a couple of years ago.
Many thanks. Tony.

[GiveMeABreak]

Yes, that is a perfectly logical reason for this to happen and will of course affect the heights. The whole unit is clamped onto the ARB at the position shown and the sensor is then calibrated using Lexia / Diagbox to ensure the heights are within the tolerance of the reference values. Once the heights are calculated and the values set - ANY movement of the clamp that rotates the sensor about the Anti Roll Bar will change the data the sensor sends to the suspension ECU, which will then begin making height corrections on the relevant axle to compensate.

That is why before removing the sensor, a setting rod (see warning note to remove when refitting in red in my notes) is used to peg the position of the internal sensor. If you are replacing the same sensor, then the position on the ARB should be marked with some white paint or a marker so that it is secured back in as near the exact location as it was originally, and then when it is connected and the setting rod removed, it should be in exactly the same position before it was removed.

The slightest movement of the clamp out of original position can make a significant difference to the ride height - unless it is calibrated again using the procedure above.

So any movement in the rotation of the sensor will change the potentiometer position and hence the data and height setting.

That is why the suspension ECU has the reference heights programmed in, so that when measuring and performing the height calculations, you can check if they are within the allowed range - if not then a slight adjustment can be made using Diagbox, but if they are significantly out, then a mechanical adjustment has to be made as described.

Now assuming your values are not way out of kilter as checked with diagbox, the other reason that the rear may not rise is the suspension ECU has gone into one of several backup modes. Several of these modes will inhibit the height correction (across the entire front, rear or both axles ) function entirely - as in the case of a faulty height sensor - so until the issue is tracked down it may not even raise the car at all, as an example. Again, the fault code from Lexia / Diagbox will help us determine the culprit - Sensor / data signal / earth / short etc. Small variations are tolerated and may be noticed as the car riding a little high or low - and could be as a result of a seized dog & Bone or corroded contacted internally.

[maximus2]

Thanks Marc.
May now take it back to garage to get it on hoist. Rolling around under car is doing me no good at all!!

[Hell Razor5543]

And it will do worse if she should drop while you are underneath her!

IIRC once the height is within 10mm of the correct height you would use a Lexia for fine adjustments.

[maximus2]

And it will do worse if she should drop while you are underneath her!

IIRC once the height is within 10mm of the correct height you would use a Lexia for fine adjustments.

I assume your talking about the car?!!