7.2 Springs, Struts, Arms, Air Suspension & Ride Height

Separate condition from modification

Inspect the suspension as fitted, then decide whether any change is excluded from LVV certification. A vehicle can fail for condition even when its modification is certified, and can fail for missing certification even when components look new.

Springs, arms, struts, and air systems

Page 9-1 covers shock absorbers, springs, upper and lower arms, sway bars, air suspension, and kingpins. Reject components or mountings that are insecure, cracked, fractured, deformed, excessively worn, seized, or have play beyond manufacturer specifications. Check spring seats, locating features, U-bolts, control-arm pivots, strut towers, and subframe points.

A spring must remain correctly located through suspension travel. Reject a cut or heated spring, a spring not self-retaining in its seat, or makeshift wire ties/straps used to keep it captive. Check leaf springs for fracture, displacement, insecure clamps, worn eyes/bushes, and axle attachment problems.

For air suspension, inspect bellows at normal ride height and pressure. Obvious external damage with protruding or worn cords is a reason for rejection. Apply the excessive air-leakage and operation rules; do not fail harmless moulding seams as cracks without evidence.

Uncertified replacement-spring route

The modification table can exclude direct replacement springs and shock absorbers from LVV certification only when every condition is met. Important conditions include:

• unmodified OE spring seats and mountings;
• springs self-retaining at full extension without non-standard retainers;
• no heating, cutting, or non-OE height adjustment;
• adequate suspension travel and clearance;
• more than 40 mm rebound (droop) wheel travel; and
• at least 100 mm ground clearance, unladen and without the driver, below the vehicle structure or steering, braking, or suspension components, subject to the VIRM note.

This is not a general statement that “up to 50 mm lowering never needs certification.” The table’s conditions, geometry, travel, and component type all matter.

Strut or spring spacers always require certification. Leaf-spring blocks can be excluded only under their detailed conditions, including no other raising method and blocks no more than 50 mm high. OE torsion-bar or OE adjustable-air-suspension adjustments have their own route.

Certified ride height

Where suspension is LVV-certified, measure from the wheel centre to the underside of the wheel arch with the vehicle unladen as directed. Reject when the current ride height differs from the value listed on the LVV plate. Also confirm the plate covers the components actually fitted.

Inspection sequence

1. Observe stance and compare side-to-side height.
2. Inspect springs, seats, arms, struts, bars, kingpins, bellows, and mountings.
3. Safely load/unload joints using the proper jacking points and method.
4. Check travel, bump-stop clearance, tyre/body clearance, and ground clearance.
5. Identify spacers, adjustable seats, blocks, air conversions, or changed mounts.
6. Apply every condition in the modification-table exclusion.
7. Compare certified ride height and hardware to the LVV record.

Scenario

A car has non-adjustable lowering springs that remain captive and clears the ground by 105 mm, but rebound travel measures 30 mm. It does not meet the full uncertified exclusion, because the table requires more than 40 mm rebound; ground clearance alone is not enough.

Modification-table discipline

Measure rebound as the difference between the tyre-to-arch reference with the vehicle resting and at full rebound, following the note; record the points so the result can be repeated. Ground clearance is checked in the specified unladen state and excludes only items the note excludes. An exhaust or cosmetic part may have a different rule than structure, steering, brakes or suspension, so quote the actual low point.

Inspect bump stops and spring aids. A high-density bump stop is not intended to carry the vehicle continuously; a compliant spring aid can engage under loading as described in the note. Cut stops, coil bind, tyre contact, and insufficient travel can fail even when static ride height matches a plate. Adjustable spring seats are not made acceptable by locking them at factory height.

Condition still controls after certification

An LVV plate confirms an approved configuration at certification; it does not excuse later wear, loose adjusters, leaking dampers, cracked arms, tyre contact or corrosion. Compare identifiers and listed height/components, then perform the full in-service inspection. If hardware differs from the certified description, treat it as an uncovered modification. If hardware matches but is worn or damaged, fail under the ordinary condition reason rather than calling the plate invalid.