1985 Rolls Royce Silver Spirit 6.8L Petrol · C27 BYX

The SZ generation employs a complex Citroën-licensed dual-circuit hydraulic system operating at over 2,000 psi to power the braking system and rear self-levelling suspension. The nitrogen-charged brake accumulator spheres lose pressure over 5 to 8 years, resulting in a rock-hard brake pedal, prolonged pump cycle times, and reduced reserve braking capacity. If brake fluid types are mistakenly interchanged (such as adding standard DOT fluid into mineral oil systems), internal rubber seals dissolve, triggering catastrophic system failure.

The hydropneumatic rear self-levelling suspension relies on two nitrogen-filled gas spring spheres connected to rear hydraulic struts to provide spring compliance and damping. Over time, nitrogen gas permeates across the internal rubber diaphragm, reducing the gas volume until the sphere hydraulically locks solid. This eliminates rear suspension compliance, transmits harsh road shocks directly into the monocoque body, and causes rapid failure of rear subframe bushes and lower shock absorber mountings.

The 6.75-litre L-Series V8 produces substantial thermal load within a heavily enclosed engine compartment. Over thousands of heat cycles, the cast-iron exhaust manifolds warp and stress their mounting studs, causing the composite manifold gaskets to blow out or the cast manifolds to develop hairline fatigue fractures. Remediation requires extracting seized or snapped studs from the aluminium cylinder heads in extremely tight engine bay clearances, demanding substantial specialist labour.