Product Details
BC Racing ER Series Coilovers for the 2017+ Audi A4/S4 (53mm Front Strut) (B9) put race-grade adjustability in reach of the serious track-day driver, with independent compression and rebound tuning at every corner. Every kit is extensively tested on the B9 chassis and refined until it balances ride quality with performance — the reason A4/S4 (53mm Front Strut) coilovers from BC Racing are the best-selling adjustable kits in their segment worldwide.
ER Series kits run a linear twin-piston design in a mono-tube body, with compression and rebound on separate external adjusters. That lets you fine-tune chassis balance corner by corner — stiffer front for turn-in, softer rear for exit grip, whatever the session calls for. BC Racing takes pride in choosing spring rates and damper valving that balance comfort and performance — you never end up with the oversprung, harsh-riding kit some brands ship as their only option. Drivers who want to deviate from the factory setup can order Swift Springs, custom spring rates, and custom valving at checkout; BC will re-valve the dampers to match whatever you specify, a level of customization most brands reserve for their top-tier race kits.
BC Racing's reputation in the aftermarket suspension world is built on four things: competitive pricing that beats the rest of the fully-adjustable market, customization depth that rivals the top-tier race brands, long-term reliability earned over 20 years of production, and a rebuildable design that keeps the same set of dampers serving you through multiple builds. These A4/S4 (53mm Front Strut) coilovers arrive tuned for the B9 chassis and ready to bolt in — no break-in period, no guessing at setup. Every kit ships with a 2-year manufacturer warranty, lifetime access to BC service parts (pistons, seals, shafts — no unit replacement required when it's time for a rebuild), and in-house tech support from both BC Racing and the Springrates team.
Features
- 30-level rebound adjustment (top of damper)
- 30-level compression adjustment (external reservoir)
- Mono-tube damper with linear twin-piston design
- Ride height adjustable independent of spring preload
- Upper mount hardware varies by chassis — camber plates, pillowball, or reused OEM mounts. See the Specifications table for what's included on your kit.
- Swift Spring and custom spring rate upgrades available at checkout
- Custom damper valving paired with custom spring rates on request
- Fully rebuildable — replacement parts available from BC for the life of the shock
- 2-year manufacturer warranty against defects
Specifications
| Part Number | S-27-ER |
| Part Name | ER Series Coilovers |
| Vehicle | 2017+ Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9) |
| Drivetrain | FWD/AWD |
| Chassis Code | B9 |
| Damping Adjustment | 2-Way (30 levels rebound / 30 levels compression) |
| Ride-Height Adjustable | Yes |
| Spring Rate - Front | 10 kg/mm |
| Spring Rate - Rear | 8 kg/mm |
| Spring Size - Front | 62-220-10K |
| Spring Size - Rear | 62-190-8K |
| Swift Springs - Front | 62-203-X |
| Swift Springs - Rear | 62-178-X |
| Camber Plates - Front | Not Applicable |
| Camber Plates - Rear | Not Applicable |
| Suspension Design - Front | True Coilover |
| Suspension Design - Rear | True Coilover |
| Notes |
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Vehicle Fitment
- 2017 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2018 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2019 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2020 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2021 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2022 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2023 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2024 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2025 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)
- 2026 Audi A4/S4 (53mm Front Strut) (FWD/AWD) (B9)