Tein Flex Z Coilover Kit - 2017-2021 Honda Civic Si Sedan / Coupe | FC1 / FC3 (VSHL6-CUAA4-C)

Transform your Civic Si's handling with the Tein Flex Z coilover kit. Engineered specifically for the 2017-2021 Honda Civic Si in both sedan (FC1) and coupe (FC3) body styles, the VSHL6-CUAA4-C delivers Tein's proven Flex Z platform — a fully adjustable coilover system with 16-way damping adjustment, ride height adjustment, and EDFC compatibility — giving Civic Si owners the tools to dial in their suspension for street comfort, canyon carving, or track day performance.

Note: Wheel alignment required after installation. Ride height and damping adjustments should be made incrementally and the vehicle test driven after each change. EDFC motor kit sold separately if electronic damping adjustment is desired.

Key Features:

• Tein Flex Z coilover kit — complete front and rear set
• 16-way damping force adjustment
• Ride height adjustable via lower bracket
• EDFC (Electronic Damping Force Controller) compatible
• Direct fit for 2017-2021 Honda Civic Si — sedan (FC1) and coupe (FC3)
• Tein's SUPER DRIVE spring specification
• Mono-tube shock absorber design
• Tein quality and engineering — made in Japan
• 66 lbs (complete kit)

Performance Benefits:

• 16-Way Damping Adjustment: 16 individual damping settings allow precise tuning of the suspension's response to road inputs — from a softer, more compliant setting for daily driving to a firmer, more controlled setting for spirited driving or track use
• Ride Height Adjustment: Lower bracket ride height adjustment allows the Civic Si to be lowered for improved handling and appearance, with the ability to fine-tune ride height independently of spring preload
• Improved Handling: Lower centre of gravity, reduced body roll, and tunable damping provide a significant improvement in cornering response, turn-in precision, and overall handling balance compared to the factory suspension
• EDFC Compatibility: The Flex Z is compatible with Tein's EDFC (Electronic Damping Force Controller) system, which allows damping adjustment from inside the cabin without getting out of the car — ideal for drivers who want to switch between street and track settings on the fly
• Mono-Tube Design: Mono-tube shock absorber construction provides more consistent damping performance than twin-tube designs, particularly under sustained use where heat buildup can cause twin-tube fade
• Made in Japan: Tein manufactures their coilovers in Japan to strict quality standards, ensuring consistent performance and durability

Specifications:

• Brand: Tein
• Part Number: VSHL6-CUAA4-C
• Series: Flex Z
• Damping Adjustment: 16-way
• Height Adjustment: Yes — lower bracket
• EDFC Compatible: Yes (EDFC motor kit sold separately)
• Shock Type: Mono-tube
• Spring Specification: Tein SUPER DRIVE
• Application: 2017-2021 Honda Civic Si — FC1 (sedan) / FC3 (coupe)
• Weight: 66 lbs (complete kit)
• Barcode: 4589533502367
• Origin: Made in Japan

Fitment Information:

• 2017-2021 Honda Civic Si Sedan (FC1 chassis)
• 2017-2021 Honda Civic Si Coupe (FC3 chassis)
• Note: Civic Si specific — verify fitment for standard Civic, Civic Sport, or Civic Type R applications as different kits apply
• Note: Wheel alignment required after installation — use an alignment shop familiar with lowered Honda applications
• Note: EDFC motor kit sold separately if electronic in-cabin damping adjustment is desired
• Installation: Professional installation recommended — coilover installation requires spring compressor and suspension knowledge

What's Included:

• Tein Flex Z coilover kit — complete front and rear set (VSHL6-CUAA4-C)
• Front strut assemblies (x2)
• Rear shock/spring assemblies (x2)
• All mounting hardware
• Note: Refer to Tein installation instructions for complete parts list
• Note: EDFC motor kit not included — sold separately

Installation Notes:

• Professional installation recommended
• Spring compressor required for front strut assembly
• Transfer factory bump stops and dust boots — verify if Tein replacements are included
• Torque all fasteners to Tein and Honda specifications with suspension at ride height
• Set initial ride height and damping before alignment — make final ride height adjustments before alignment appointment
• Full wheel alignment required after installation — do not drive without alignment check
• Start with a mid-range damping setting (8 of 16) and adjust from there based on driving feel

Tein Flex Z — The Platform:

The Tein Flex Z is Tein's mid-range street and sport coilover, positioned above Tein's entry-level Street Advance Z and below the track-focused Mono Sport and Mono Racing lines. The Flex Z is designed for drivers who want a meaningful suspension upgrade over the factory setup with genuine adjustability — the 16-way damping adjustment provides a wide range of tuning capability that covers everything from a comfortable daily driver setting to a firm sport setting suitable for track days and autocross.

The Flex Z uses a mono-tube shock absorber design, which provides more consistent damping performance than the twin-tube design used in many entry-level coilovers. Mono-tube shocks have a larger piston diameter for a given shock body size, providing more precise damping control and better heat dissipation — important for sustained performance driving where the shock absorbers are working hard. The Flex Z's SUPER DRIVE spring specification is Tein's street-optimized spring rate selection for each application, balancing ride quality with handling improvement for the specific vehicle's weight and geometry.

16-Way Damping Adjustment — How to Use It:

The Flex Z's 16-way damping adjustment is made via an adjuster at the top of each shock absorber. Turning the adjuster clockwise increases damping force (firmer), and counterclockwise decreases it (softer). The 16 positions provide a meaningful range of adjustment — position 1 is the softest setting, position 16 is the firmest. For most street use, a setting in the range of 6-10 provides a good balance of comfort and control. For track use, settings of 12-16 provide maximum body motion control at the expense of ride comfort over rough surfaces.

The key to getting the most from the 16-way adjustment is to make changes incrementally and test drive after each adjustment. Changing multiple positions at once makes it difficult to identify the effect of each change. Start at a mid-range setting, drive the car on your typical roads, and adjust up or down based on whether the car feels too soft (body roll, dive, squat) or too firm (harsh over bumps, loss of traction over rough surfaces). The EDFC system, if added, allows these adjustments to be made from inside the cabin without stopping — allowing real-time tuning on a track or mountain road.

Honda Civic Si FC1/FC3 — Suspension Context:

The 10th-generation Honda Civic Si (2017-2021) uses a MacPherson strut front and multi-link rear suspension — a significant improvement over the previous generation's torsion beam rear. The Si-specific suspension tuning provides a sportier baseline than the standard Civic, but the factory setup is still calibrated for a broad range of drivers and road conditions rather than maximum performance. The factory ride height leaves significant room for improvement in terms of centre of gravity and roll resistance, and the factory dampers have limited adjustment capability.

The Tein Flex Z addresses both of these limitations: the ride height adjustment allows the Civic Si to be lowered for improved handling and appearance, and the 16-way damping adjustment allows the suspension's response to be tuned for the driver's specific preferences and use case. The result is a Civic Si that handles significantly better than stock — with less body roll, more precise turn-in, and more consistent cornering balance — while retaining the daily drivability that makes the Civic Si such a popular platform.

Why Tein?

Tein is one of Japan's most respected suspension manufacturers, with decades of experience developing coilovers, springs, and suspension components for a wide range of vehicles. Their products are developed and manufactured in Japan to strict quality standards, and their coilover lineup covers a wide range of applications and performance levels. The Flex Z is one of Tein's most popular products globally, trusted by enthusiasts who want genuine Japanese engineering quality and proven performance at a competitive price point. For Civic Si owners who want a coilover kit they can be confident in, Tein is a benchmark choice.

Perfect For:

• 2017-2021 Honda Civic Si sedan (FC1) and coupe (FC3) owners wanting a complete coilover upgrade with 16-way damping adjustment
• Civic Si street builds wanting improved handling, reduced body roll, and a lower ride height with daily drivability
• Civic Si track day and autocross builds wanting tunable damping for performance driving without sacrificing street usability
• Civic Si owners wanting EDFC-compatible coilovers for in-cabin damping adjustment between street and track settings
• Anyone wanting Tein's proven Flex Z platform in a direct-fit kit for their 2017-2021 Honda Civic Si

Perfect For: 2017-2021 Honda Civic Si FC1/FC3 owners seeking Tein Flex Z coilovers for improved handling, 16-way adjustable damping, ride height adjustment, and EDFC compatibility for street and track use.

Pro Tip: Set your target ride height before your alignment appointment and don't change it afterwards — even small ride height changes affect camber and toe on most suspension designs, and re-adjusting ride height after alignment will require another alignment visit. Measure your ride height from the centre of the wheel to the wheel arch lip at all four corners before and after installation to ensure the car is level side-to-side and has the front/rear balance you want before going to the alignment shop.

Flex Z | 16-Way Damping | Height Adjustable | EDFC Compatible: 2017-2021 Honda Civic Si FC1 sedan and FC3 coupe. Alignment required after installation. EDFC motor kit sold separately. Made in Japan. 66 lbs. Professional installation recommended.

Unlock your Civic Si's handling potential with Tein VSHL6-CUAA4-C Flex Z coilovers — 16-way damping, ride height adjustment, EDFC compatible, direct fit for 2017-2021 Honda Civic Si FC1 and FC3.