C5 Mk3 58 plate Exclusive Hydractive Suspension height

[Rablol152]

Thanks think i will just find a garage to sort it as it’s not my strong point mechanical stuff ok computers no lol

[sz1]

If you want to go in search of the rear height corrector, here's a picture of it in situ. Filth, muck and dead badgers removed to aid clarity It's the circular thing more or less in the centre of the picture, the blue thing is the anit-roll bar clamp, the bit that connects them is the 'dog bone'.

Hello Mr. Borovic,
I am looking for official data about height of C5 2.0HDI exclusive, 2009. After adjusting of heights in official garage in Varaždin, my car is 2,5 cm lower than should be: 1425 mm instead of 1451 mm, and they said it is CORRECT height.

[GiveMeABreak]

Heights are not measured like that. You need to undertake the correct height measurement procedure which is in my post here:

viewtopic.php?p=559127#p559127

[Stu-Scotland]

Just to add my question to the suspension height discussion before I swap hard disks on the laptop and go for a play, can I take a note of the current settings in Diagbox and revert to them easily if I mess up?
I know the front is high due to a local clumsy mechanic with a jacking beam, but I neither have flat ground or the proper tool, so would like to get back to somewhere around the correct levels using the wheel centre to arch method.
I know this will be far from perfect but a short-term fix will do til it stops raining here (usually sometime around August).
Obviously I want to be able to revert to current settings if I make things worse

Anyone know the answer?

[GiveMeABreak]

No you can't - there is not backup. Once you change anything it is permanent until it is replaced with another value. Advice is not to change anything regarding suspension settings, unless you have first followed the correct measuring process as detailed in my previous post.

[Stu-Scotland]

I understand there's no backup Marc, just wondered if it displayed current values so they could be re-entered if necessary.

I also understand this is Citroen we're talking about so they probably wouldn't do something that logical.
I miss coil springs sometimes

[GiveMeABreak]

No, as far as the suspension goes (and several other systems in live data), you may see reference values. These are factory set and cannot be changed, but are used to show the values or range of values that are valid. Be careful with the suspension values though as these refer to 'Steps' not measurements and are recalculated by the the data resulting from the values resulting from the measuring procedures.

[Stu-Scotland]

On well. Guess it's time to retire do the garage and bodge a measuring tool then
.Thanks Marc.

[osx]

For most C5 X7 the height values that will be accepted are 160-170 front and 100-110 rear.
Once you get both values accepted then you can tweak them. If one of the values is outside the range it will default to 128 if I remember correctly so you will have to re-enter the last values that worked. Change in steps of 5 until you find the minimum and maximum values that are accepted and then you can fine tune.

[Ford Prefect]

2 Preliminary operations

• Verify the tyre pressure.
• Place the vehicle on a 4-post lift.
• Slacken the parking brake .
• Position the body height at the high position.
• Position the body height at the normal position (driving height).
• Switch on the ignition.
• Raise the vehicle.

Two questions:

[*]Switch on the ignition.

1. To prevent the car goes into "Economy mode" - Is it OK to have the hood open and a battery charger connected to the battery during the process?

[*]Raise the vehicle.

2. Should the measurements been done with the car in the highest position and not in normal position?

[GiveMeABreak]

1) No, not necessary as the height correction is maintained by the BHI with the ignition on, regardless of economy mode, but if you have a battery in poor health, I suggest you give it a good trickle charge overnight in any case.

2) No. The measuring process must undertaken at normal ride height as the calculations are designed to end up with calculated values that will be used to compare with determined reference values. Having the vehicle at other ride heights will make the measurements totally invalid.

The last line referred to in the quote "Raise the Vehicle" does not mean raise the vehicle suspension, it means raise the vehicle on the 4 post lift as the last thing in the preliminary list of actions. Lets look at them in context:

2 Preliminary operations

• Verify the tyre pressure. This is to ensure that the tyres are correctly inflated to the recommended pressures to provide accurate measurements
• Place the vehicle on a 4-post lift. For the reasons explained in my last paragraph below
• Slacken the parking brake. As this can interfere with the process
• Position the body height at the high position. As part of a preliminary calibration to ensure suspension is moving freely
• Position the body height at the normal position (driving height). As part of a preliminary calibration to ensure suspension is moving freely
• Switch on the ignition. To allow the vehicle height to remain controlled during the measuring procedure
• Raise the vehicle.

To make it easier for the technician to take the measurements at his own body height.

The reason the vehicle is put on a 4-post lift is because a) measurements are more easily taken by the technician when the vehicle is on a level 4-post lift. b) For safety reasons, as if the car has a problem with maintaining height, there is a risk that the vehicle may come crashing down on an individual, if say one or more height correctors is faulty or an adjustment is made, with potentially fatal consequences.

[Ford Prefect]

The last line referred to in the quote "Raise the Vehicle" does not mean raise the vehicle suspension, it means raise the vehicle on the 4 post lift as the last thing in the preliminary list of actions.

Of course

(I'll know of the danger of working underneath a hydraulic Citroën but thanks for the warning )

[vallium]

I've vibecoded a simple javascript that does all the calculations for you. Just copy the code into html file and open with browser.

Code: Select all

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Vehicle Height Calculation (Citroën C5 X7)</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #f4f6f9;
            color: #333;
            margin: 0;
            padding: 20px;
        }
        .container {
            max-width: 650px;
            margin: 0 auto;
            background: #fff;
            padding: 20px;
            border-radius: 8px;
            box-shadow: 0 4px 6px rgba(0,0,0,0.1);
        }
        h1 {
            text-align: center;
            color: #2c3e50;
            font-size: 24px;
            margin-bottom: 5px;
        }
        .info-banner {
            background-color: #ebedef;
            border-left: 5px solid #7f8c8d;
            padding: 10px;
            margin-bottom: 20px;
            font-size: 14px;
            text-align: center;
            font-weight: bold;
            color: #34495e;
            border-radius: 4px;
        }
        .section {
            border: 1px solid #e0e0e0;
            border-radius: 6px;
            padding: 15px;
            margin-bottom: 15px;
            background-color: #fafafa;
        }
        .section-title {
            font-weight: bold;
            margin-bottom: 12px;
            color: #2980b9;
            border-bottom: 2px solid #2980b9;
            padding-bottom: 5px;
        }
        .sub-title {
            font-size: 13px;
            font-weight: bold;
            color: #7f8c8d;
            margin-top: 10px;
            margin-bottom: 5px;
            text-transform: uppercase;
        }
        .input-group {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 8px;
        }
        .input-group:last-child {
            margin-bottom: 0;
        }
        label {
            flex: 1;
            font-size: 14px;
            padding-right: 10px;
        }
        input {
            width: 90px;
            padding: 6px;
            border: 1px solid #ccc;
            border-radius: 4px;
            text-align: right;
            font-size: 14px;
        }
        input.calculated {
            background-color: #e2f0d9;
            border-color: #a9d08e;
            font-weight: bold;
            color: #385723;
        }
        .results {
            background-color: #e8f4f8;
            border: 2px solid #2980b9;
            border-radius: 6px;
            padding: 15px;
            margin-top: 20px;
        }
        .result-title {
            font-weight: bold;
            color: #2c3e50;
            margin-bottom: 10px;
            font-size: 16px;
            text-transform: uppercase;
            text-align: center;
        }
        .result-row {
            display: flex;
            justify-content: space-between;
            padding: 5px 0;
            font-size: 15px;
        }
        .highlight {
            font-weight: bold;
            font-size: 20px;
            color: #c0392b;
        }
    </style>
</head>
<body>

<div class="container">
    <h1>Vehicle Height Calculation<br><small style="font-size: 14px; color: #7f8c8d;">Citroën C5 (X7)</small></h1>
    
    <div class="info-banner">
        Saved default values for your vehicle
    </div>
    
    <div class="section">
        <div class="section-title">FRONT (Axis 1)</div>
        
        <div class="sub-title">Left wheel (1)</div>
        <div class="input-group">
            <label>Rim diameter (in mm):</label>
            <input type="number" id="plat_r1" value="469" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Tyre sidewall height (in mm):</label>
            <input type="number" id="guma_r1" value="81" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Calculated radius R1 (mm):</label>
            <input type="number" id="r1" class="calculated" readonly>
        </div>
        <div class="input-group" style="margin-bottom: 15px;">
            <label><strong>Measured body height H1 (mm):</strong></label>
            <input type="number" id="h1" value="171" oninput="izracunaj()">
        </div>

        <div class="sub-title">Right wheel (1')</div>
        <div class="input-group">
            <label>Rim diameter (in mm):</label>
            <input type="number" id="plat_r1_p" value="469" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Tyre sidewall height (in mm):</label>
            <input type="number" id="guma_r1_p" value="81" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Calculated radius R1' (mm):</label>
            <input type="number" id="r1_p" class="calculated" readonly>
        </div>
        <div class="input-group">
            <label><strong>Measured body height H1' (mm):</strong></label>
            <input type="number" id="h1_p" value="172" oninput="izracunaj()">
        </div>
    </div>

    <div class="section">
        <div class="section-title">REAR (Axis 2)</div>
        
        <div class="sub-title">Left wheel (2)</div>
        <div class="input-group">
            <label>Rim diameter (in mm):</label>
            <input type="number" id="plat_r2" value="469" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Tyre sidewall height (in mm):</label>
            <input type="number" id="guma_r2" value="92" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Calculated radius R2 (mm):</label>
            <input type="number" id="r2" class="calculated" readonly>
        </div>
        <div class="input-group" style="margin-bottom: 15px;">
            <label><strong>Measured body height H2 (mm):</strong></label>
            <input type="number" id="h2" value="233" oninput="izracunaj()">
        </div>

        <div class="sub-title">Right wheel (2')</div>
        <div class="input-group">
            <label>Rim diameter (in mm):</label>
            <input type="number" id="plat_r2_p" value="469" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Tyre sidewall height (in mm):</label>
            <input type="number" id="guma_r2_p" value="88" oninput="izracunaj()">
        </div>
        <div class="input-group">
            <label>Calculated radius R2' (mm):</label>
            <input type="number" id="r2_p" class="calculated" readonly>
        </div>
        <div class="input-group">
            <label><strong>Measured body height H2' (mm):</strong></label>
            <input type="number" id="h2_p" value="228" oninput="izracunaj()">
        </div>
    </div>

    <div class="results">
        <div class="result-title">Values for Diagnostic Tool</div>
        <div class="result-row" style="border-bottom: 1px dashed #bdc3c7; padding-bottom: 10px; margin-bottom: 10px;">
            <span>FRONT INPUT VALUE:</span>
            <span id="vnos_spredaj" class="highlight">--</span>
        </div>
        <div class="result-row" style="margin-bottom: 15px;">
            <span>REAR INPUT VALUE:</span>
            <span id="vnos_zadaj" class="highlight">--</span>
        </div>
        
        <div class="result-title" style="font-size: 13px; color: #7f8c8d; border-top: 1px solid #bdc3c7; padding-top: 10px;">Control Values (K)</div>
        <div class="result-row" style="font-size: 13px; color: #555;">
            <span>Current K Front (Ref: 160 ± 6 mm):</span>
            <span id="trenutni_k1">--</span>
        </div>
        <div class="result-row" style="font-size: 13px; color: #555;">
            <span>Current K Rear (Ref: 106 ± 6 mm):</span>
            <span id="trenutni_k2">--</span>
        </div>
    </div>
</div>

<script>
function pretvoriVPolmer(premerMm, gumaMm) {
    return (premerMm / 2) + gumaMm;
}

function izracunaj() {
    // 1. FRONT: Calculate radii R
    const plat_r1 = parseFloat(document.getElementById('plat_r1').value) || 0;
    const guma_r1 = parseFloat(document.getElementById('guma_r1').value) || 0;
    const r1 = pretvoriVPolmer(plat_r1, guma_r1);
    document.getElementById('r1').value = r1.toFixed(1);

    const plat_r1_p = parseFloat(document.getElementById('plat_r1_p').value) || 0;
    const guma_r1_p = parseFloat(document.getElementById('guma_r1_p').value) || 0;
    const r1_p = pretvoriVPolmer(plat_r1_p, guma_r1_p);
    document.getElementById('r1_p').value = r1_p.toFixed(1);

    const h1 = parseFloat(document.getElementById('h1').value) || 0;
    const h1_p = parseFloat(document.getElementById('h1_p').value) || 0;

    // 2. REAR: Calculate radii R
    const plat_r2 = parseFloat(document.getElementById('plat_r2').value) || 0;
    const guma_r2 = parseFloat(document.getElementById('guma_r2').value) || 0;
    const r2 = pretvoriVPolmer(plat_r2, guma_r2);
    document.getElementById('r2').value = r2.toFixed(1);

    const plat_r2_p = parseFloat(document.getElementById('plat_r2_p').value) || 0;
    const guma_r2_p = parseFloat(document.getElementById('guma_r2_p').value) || 0;
    const r2_p = pretvoriVPolmer(plat_r2_p, guma_r2_p);
    document.getElementById('r2_p').value = r2_p.toFixed(1);

    const h2 = parseFloat(document.getElementById('h2').value) || 0;
    const h2_p = parseFloat(document.getElementById('h2_p').value) || 0;

    // 3. Calculate intermediate values K (K = R - H)
    const k1 = r1 - h1;
    const k1_p = r1_p - h1_p;
    const povprecje_k1 = (k1 + k1_p) / 2;

    const k2 = r2 - h2;
    const k2_p = r2_p - h2_p;
    const povprecje_k2 = (k2 + k2_p) / 2;

    // 4. Calculations for diagnostic equipment
    const vnos_spredaj_vrednost = 320 - povprecje_k1;
    const vnos_zadaj_vrednost = 212 - povprecje_k2;

    // 5. Output final results
    document.getElementById('vnos_spredaj').innerText = Math.round(vnos_spredaj_vrednost) + " mm";
    document.getElementById('vnos_zadaj').innerText = Math.round(vnos_zadaj_vrednost) + " mm";
    
    document.getElementById('trenutni_k1').innerText = povprecje_k1.toFixed(1) + " mm";
    document.getElementById('trenutni_k2').innerText = povprecje_k2.toFixed(1) + " mm";
}

// Automatic first calculation upon loading the page
window.onload = izracunaj;
</script>

</body>
</html>

Tire data in app are for 225/55r17 tires on factory Baltique rims. Correct heights (H-values) should be around 155 mm in front and 210 mm in rear. As seen my car was 16 mm too high in front and 20 mm in the rear. Comfort is not revolutionised but it's definitely noticeable. Something worth doing if you have access to Diagbox. I would also recommend getting an el cheapo laser distance meter.