B8 / B9 Multi-Link Rear Suspension
The B8 and B9 A4, A5, and Q5 use a trapezoidal multi-link rear suspension — each rear corner controlled by multiple arms and bushings. The design provides precise handling but introduces more wear points than a simpler trailing-arm setup. Key wear items:
| Component | Typical Wear Mileage | Symptom |
|---|---|---|
| Rear control arm bushings | 80,000–100,000 mi | Vague handling, clunk over bumps |
| Rear trailing arm bushings | 80,000–100,000 mi | Rear-end wander on highway |
| Rear toe link | 70,000–90,000 mi | Toe instability, uneven rear tire wear |
| Front lower control arms | 80,000–120,000 mi | Vibration at highway speed, clunk on acceleration |
| Front sway bar links / bushings | 60,000–80,000 mi | Clunk over bumps, rattling on uneven roads |
| Front strut mounts | 80,000–100,000 mi | Clunk on full lock, knock over bumps |
Sway bar links and end links are the highest-wear low-cost items — often overlooked at service because the symptom (clunk over bumps) is easy to defer. Replacing end links at $80–$150 each prevents premature sway bar bushing wear. Do them together.
Alignment Requirements After Suspension Work
Any suspension component replacement on an Audi requires a four-wheel alignment — including sway bar links, which some shops skip alignment after. Audi's quattro all-wheel-drive system is sensitive to toe and camber alignment: incorrect alignment causes uneven tire wear rapidly and generates AWD driveline strain. A proper quattro alignment requires a 4-wheel alignment rack, Audi-specific alignment specs, and a technician who knows the adjustment sequence on multi-link geometry. Budget $120–$180 for alignment after any suspension service.
Air Suspension Systems
Multiple Audi models use air suspension — standard or optional on A6/A7, Q5, Q7, and others. Air suspension delivers a remarkable ride quality range: comfort to dynamic via driver-selectable modes. The tradeoff is more components that can fail.
Air Strut Failure
The most common air suspension failure is air strut leak — the rubber air sleeve that forms the spring element develops a leak, causing that corner to sit lower than the others. Symptoms: car noticeably lower on one corner after sitting overnight, compressor running audibly at startup and struggling to level the car, or the car displaying a "Suspension: Fault" message. Slow leaks may take days to show; fast leaks show within hours.
| Model | Air Strut Cost (each) | Labor per strut | Total (one strut) |
|---|---|---|---|
| A6/A7 C7 | $300–$550 | $150–$250 | $450–$800 |
| Q5 (air suspension) | $350–$600 | $150–$250 | $500–$850 |
| Q7 4L/4M | $500–$900 | $200–$350 | $700–$1,250 |
Air Compressor
The air compressor fills and maintains system pressure. Compressors typically last 100,000–130,000 miles. A failing compressor runs constantly without achieving target pressure, or fails to start. Replacement: $400–$700 parts plus 1–2 hours labor. Replace the intake filter at the same time — a restricted filter is what prematurely kills compressors.
Lowering Springs and Coilover Conversions
Owners considering suspension modifications: aftermarket lowering springs (H&R, Eibach) are available for most B8/B9 models and drop ride height 1–1.5 inches while improving handling. Coilover kits (KW, Bilstein) offer height adjustability and damper tuning. Any lowering beyond 1 inch requires camber correction (adjustable arms or plates) and a fresh alignment. We can discuss options specific to your car and use case.