Smart Roadster Suspension Parts: Upgrade Guide and Buying Tips

The smart roadster is a lightweight, mid-engined two-seater that offers a unique driving experience. However, its suspension components are known to wear over time, and many owners look to upgrade for better handling or ride quality. Whether you're replacing worn parts or building a track-day toy, understanding your options for smart roadster suspension parts is essential. This guide covers the key components, common upgrades, and what to consider before buying.

Key Suspension Components for the Smart Roadster

The smart roadster shares some parts with the fortwo, but its suspension setup is distinct. The front uses MacPherson struts, while the rear has a semi-independent torsion beam. Here are the main parts you'll encounter:

Shock Absorbers and Struts

Shocks are the most frequently replaced item. Original equipment (OE) shocks tend to be soft and can become bouncy after 50,000 miles. Aftermarket options include:

• Bilstein B4 – OEM replacement with slightly firmer damping.
• Bilstein B6 – Heavy-duty, ideal for spirited driving.
• Bilstein B8 – Shortened body for lowered cars.

Springs

Factory springs have a progressive rate. Lowering springs (e.g., Eibach Pro-Kit) drop the car about 30mm, reducing body roll. For track use, coilover sleeves or full coilover kits offer ride-height adjustability.

Bushings and Mounts

Rubber bushings in the control arms and sway bar mounts deteriorate with age. Polyurethane bushings from Powerflex or SuperPro firm up the chassis without being harsh. Replace strut top mounts if they're cracked.

Sway Bar (Anti-Roll Bar)

The stock sway bar is thin. Upgrading to a thicker bar (e.g., from the smart Brabus or aftermarket) significantly reduces lean in corners. Some kits include adjustable links.

Common Upgrades and Their Benefits

Complete Coilover Kits

Coilover sets from KW, Bilstein, or H&R replace the strut, spring, and adjuster in one unit. They allow independent ride height and damping adjustment. Pros: best handling, tunable. Cons: cost (typically $1,200–$2,000), and they can be stiff for daily driving.

Lowering Springs Alone

If you want a sportier look without full adjustability, lowering springs paired with upgraded shocks are a cost-effective step. Dropping the center of gravity improves cornering. Expect a firmer ride.

Polyurethane Bushing Sets

Replacing all control arm bushes and sway bar bushes with polyurethane reduces wheel hop and sharpens steering response. It's a DIY-friendly upgrade that doesn't break the bank.

Shock Tower Brace

A front strut brace ties the shock towers together, reducing chassis flex. This is especially noticeable on the roadster because of its open-top design (the roadster coupe benefits too). Several manufacturers offer bolt-on braces.

Factors to Consider When Buying

Driving Use

• Daily driving: Stick with OEM-quality shocks and progressive springs. Bilstein B4 or KYB Excel-G are comfortable.
• Spirited road driving: Bilstein B6 or Koni Special Active. Add a rear sway bar.
• Track days: Coilovers with camber plates. Consider adjustable damping.

Compatibility

Smart roadster suspension parts are model-year specific (2003–2005) and sometimes differ between coupe and convertible due to weight. Always confirm part numbers with your vehicle's VIN.

Installation Complexity

Shocks and springs require spring compressors and can be done at home if you have tools. Bushings need a press. Coilover installation is straightforward for those experienced. If not, budget $300–$600 for a shop labor.

Budget

• Basic replacement: $200–$400 for shocks/struts.
• Lowering springs: $200–$300.
• Full coilover kit: $1,200–$2,000.
• Bushing set: $150–$250.
• Installation if not DIY: add $300–$600.

Maintenance Tips for Longevity

• Inspect rubber parts every two years. UV and heat degrade them.
• Grease polyurethane bushings annually with silicone grease to prevent squeaks.
• Torque all suspension bolts to specification after a few hundred miles of driving.
• Consider a wheel alignment after any ride height change.

Final Recommendation

For most smart roadster owners, the best balance of cost and improvement is to replace worn shocks with Bilstein B6 units and add a set of Eibach lowering springs. This combo transforms the car's handling without ruining ride comfort. If you track the car, invest in a full KW or Bilstein coilover kit with adjustable damping. For those on a tight budget, simply refreshing all rubber bushings with polyurethane will tighten up the feel noticeably. Always prioritize safety: if your shocks are leaking or your springs are sagging, replace them immediately. A well-sorted suspension makes the smart roadster a joy to drive on twisty roads, and the aftermarket offers plenty of proven parts at reasonable prices.