Sankei 555 Suspension Parts: Performance, Fitment, and Buying Guide

Sankei is a well-respected Japanese manufacturer known for producing durable, high-performance suspension components. Their 555 series is designed to offer a balance of adjustability, comfort, and track-ready capability. Whether you drive a drift car, a weekend track toy, or a daily driver that needs sharper handling, Sankei 555 suspension parts can be a solid upgrade over OEM or budget coilovers.

What Makes Sankei 555 Suspension Parts Different?

The 555 series sits in the mid-to-high range of Sankei's lineup. It uses monotube shock technology, which provides more consistent damping and better heat dissipation than twin-tube designs. The shocks are fully rebuildable, which extends their lifespan and allows for custom valving if your needs change. The springs are made from high-tensile steel and come in a range of spring rates, typically from 6 kg/mm to 14 kg/mm, depending on the application.

Key Features of the 555 Series

• Fully adjustable damping: Most 555 coilovers offer 30 to 36 clicks of rebound and compression adjustment. This lets you fine-tune the ride for street, mountain roads, or track use.
• Ride height adjustable: Height adjustment is done via the spring perch, which does not affect shock travel. This is important because lowering too much can reduce suspension stroke and cause bottoming out.
• Pillowball top mounts: The front top mounts use pillowball bearings, which reduce deflection and provide sharper steering response. Some kits include camber-adjustable top plates, helpful for alignment.
• Dust boots and bump stops: Included to protect the shock shaft and prevent damage on full compression.

Fitment for Popular Vehicles

Sankei 555 suspension parts are available for a wide range of Japanese and European cars. Common applications include:

Nissan Models

• Silvia S13/S14/S15: The 555 kit for these chassis is a favorite among drifters. Spring rates around 8/6 kg/mm (front/rear) work well for street and occasional track use. The coilovers are designed to clear brake lines and allow camber adjustment.
• Skyline R32/R33/R34: For GT-Rs and GT-Ts, the 555 series offers spring rates up to 12 kg/mm for heavy cars. The shocks have longer travel to accommodate the heavier weight.
• 350Z / 370Z: These kits come with front camber plates and rear lower brackets to maintain geometry when lowered.

Mazda Models

• RX-7 FD3S: The 555 coilovers are popular for rotary-powered cars. Spring rates 8/6 or 10/8 kg/mm. The kit includes front camber plates and rear pillowball mounts.
• Miata MX-5 (NA/NB/NC): For the lightweight MX-5, Sankei offers 555 with softer springs (6/4 or 7/5) to preserve ride quality while improving cornering.

Subaru Models

• Impreza WRX / STI (GD/GG): These kits have inverted front struts for increased rigidity. Spring rates 8/6 or 10/8 kg/mm. The rear shocks have separate height and preload adjustment.
• Legacy / Outback: Less common, but available for specific years. Check vehicle compatibility.

Toyota Models

• Supra MKIV: Spring rates 10/8 or 12/10 kg/mm. The 555 kit includes heavy-duty top mounts to handle the torque.
• AE86 / Corolla: This is a classic drift setup. Spring rates 8/6 kg/mm. The coilovers are short enough for low ride heights without binding.

How to Choose the Right Spring Rate

Spring rate selection depends on your vehicle weight, driving style, and tire grip. For a street car that sees occasional track days, a rate around 8 kg/mm front and 6 kg/mm rear is a good starting point for most Japanese sports cars. If you are heavier (like a Skyline), consider 10/8 or 12/10. For dedicated drift or grip competition, rates as high as 14/12 are used. Softer springs (6/4) are better for rough roads or daily comfort.

Tips for Selecting Spring Rates

• Weight distribution: Front-heavy cars need higher front rates to control dive and roll.
• Tire grip: With sticky semi-slicks, you need stiffer springs to prevent the tire from rolling over.
• Adjustable damping: With the 555's 36-click adjustability, you can compensate for slightly incorrect spring rates within reason. But it's better to get the right spring rate first.

Damping Adjustment for Street vs. Track

The 555 series allows you to set both rebound and compression independently. A common starting point for the street is 12-15 clicks from full stiff for rebound, and 10-12 clicks for compression. For track use, go stiffer: 5-8 clicks from full stiff. Always adjust in small increments. If the car bounces over bumps, reduce rebound stiffness. If it bottoms out on curbs, increase compression.

Installation and Setup Tips

Installing coilovers yourself is possible if you have basic mechanical skills and spring compressors. However, setup such as preloading the springs and setting ride height correctly affects performance.

Ride Height Setting

• Measure from the fender lip to the center of the wheel before installing. Lower the car no more than 1.5 inches from stock to maintain suspension geometry. Too low can cause bump steer and bottoming out.
• Set the height with the car on level ground. After tightening, bounce the suspension a few times and re-measure.

Camber and Toe

• After lowering, you'll likely need a professional alignment. Pillowball top mounts allow camber adjustment, but toe is still set by the tie rods. Get camber within -1.5 to -2.5 degrees for performance street use. Too much negative camber wears tires unevenly.
• Rear camber may require adjustable arms. The 555 kit does not always include those.

Maintenance and Rebuilding

One advantage of Sankei 555 coilovers is they are rebuildable. Over time, seals can wear or oil can degrade, especially in harsh climates. A rebuild costs less than new units. Sankei recommends servicing every 2-3 years for daily driving, or annually for race use. Dust boots should be checked regularly.

Signs You Need a Rebuild

• Oil leakage on the shock body
• Damping feels inconsistent or bouncy
• Knocking sounds during compression
• Ride height sagging on one corner

Sankei 555 vs. Other Options

Direct competitors include BC Racing (BR series), Tein (Flex Z), and Fortune Auto. Compared to BC Racing, Sankei 555 offers more adjustability and rebuildability. Versus Tein Flex Z, the Sankei has separate compression/rebound adjustment (Tein combines them on some models). Fortune Auto uses similar monotube design but costs more. Sankei 555 is a strong value for the price.

Final Recommendation

If you want a coilover kit that is streetable, track-capable, and rebuildable, Sankei 555 suspension parts are a smart choice. They offer excellent damping control, durable construction, and good fitment for popular performance cars. For most drivers, the mid-range spring rates (8/6 or 10/8) paired with 36-click adjustability will satisfy daily driving and weekend events. Just ensure you verify your vehicle's specific compatibility and budget for an alignment after installation. With proper setup and maintenance, a 555 suspension can transform your car's handling for years.