Recently I have noticed that a lot of consumers and dealers of ours inquire about the differences between a Japanese-spec coilover kit and a U.S.-spec coilover kit. Relax, grab a cup of coffee, and let me do some explaining. It’s actually quite simple.

One of the main differences between these kits is the valving and in some cases spring rates. The U.S.-spec coilover kit comes with a more aggressive valving. The reason behind this is because consumers in the U.S. prefer a slightly more aggressive coilover in comparison to consumers in Japan. U.S. vehicle’s may also have some manufacturing differences opposed to the ones released overseas.

But as mentioned earlier, another factor is the spring rates. Some of the U.S.-spec coilover’s come with a stiffer spring to match the aggressive valving of the dampers. Of course there are other differences between the dampers besides the valving and spring rate. Damper designs may vary from U.S. to Japanese kits such as damper mounting points, damper body and stroke lengths, and required OEM parts.

As a side note- some U.S. applications may be compatible with Japanese dampers with no modifications whatsoever. But we recommended to verify with TEIN prior to purchasing these kits.

In conclusion, regardless if the coilover kit is Japanese or US spec they both come down to one thing- they both cater to different markets which is a matter of consumer preference. However, TEIN is able to assist with customization of your TEIN dampers through our Overhaul and Revalving service available Stateside through our in-house service departments in the East Coast and West Coast facilities. As a performance suspension manufacturer for a global market, we realize it is difficult to appease all customers. But we can definitely assist our customers in dialing in their suspension for their specific needs, all of which is for your driving pleasure!