Tein Coilovers

Tein's US street lineup runs from Street Basis Z at the entry point up through Street Advance Z and Flex Z, each adding a layer of adjustment over the last. All three share the same twin-tube damper architecture and SAE9254 spring steel, so the choice between them comes down to how much control over damping and ride height you want rather than a difference in build quality. See the coilovers hub for how coilovers compare to springs and struts if you're still deciding whether a full kit makes sense.

Tein publishes application-specific kits for a wide range of chassis, including the Nissan 350Z/G35 and 370Z/G37, Mazda Miata/MX-5, Acura RSX, and Honda Civic, each with its own spring rates and shock lengths. Our 350Z/G35 coilover page, 370Z/G37 coilover page, Miata/MX-5 coilover page, and RSX coilover page cover platform-specific notes across brands.

The table below compares the three Z-series kits by adjustment and intended use.

Street Basis Z is the kit to buy if you want a clean, factory-feeling drop and don't plan to fine-tune damping. Street Advance Z adds a dial so you can firm up the ride for a weekend track day and soften it back for a daily commute, without touching ride height. Flex Z is the one to pick if you want to change ride height later without re-compressing the spring, since the threaded body sets height independently of preload, and it's the only one of the three built for EDFC's full 32 or 64-level remote adjustment on compatible models.

Tein builds application-specific Flex Z and Street Advance Z kits for the Nissan 350Z/G35 (tein 350z coilovers) and 370Z/G37, the Mazda Miata/MX-5, the Acura RSX, and other popular platforms, each with its own spring rate and drop range rather than a one-size-fits-all spring.

Tein's twin-tube, sealed-unit design sits apart from mono-tube budget brands like BC Racing, which uses a rebuildable mono-tube shock with independently sold parts. Tein's twin-tube layout is tuned more for ride comfort at a given damping setting, while BC Racing's mono-tube BR Series tends to favor a firmer, more track-oriented feel at a similar price point.

Against KW, Tein's Flex Z and Street Advance Z sit in a lower price bracket, and KW's Variant series adds features like a rebuildable shock body and a longer published warranty. Which rides better on your car depends on the specific spring rate and valving for your platform more than the brand name, so compare the actual kit specs rather than assuming one brand is universally stiffer or more comfortable.

On Flex Z, ride height is set by moving the lower locking collar on the threaded shock body, which changes how much the shock is extended without changing spring preload, so lowering the car doesn't also stiffen the ride. Street Basis Z and Street Advance Z use a simpler thread-type adjustment that moves the lower spring seat up and down the shock body. Damping on Street Advance Z and Flex Z is set with a dial at the top of the shock, or remotely through an EDFC controller on compatible models; turning it doesn't affect ride height, so height and damping can be tuned independently.

None of the three series are rebuildable in the traditional sense since they use a sealed shock body, but Tein's Replacement Service lets owners buy a new shock body while keeping the original springs, mounts, and brackets. Our coilover adjustment guide and installation and cost guide cover the general process and typical shop labor if you're not installing it yourself.