Every coilover return we see starts with the same sentence: "It says it fits my car." Fitment charts are not VIN lookups. They are a factory's build list, written in the language the factory stocks parts in — chassis codes. This guide explains how to read one, where the traps are, and how to answer a customer who has a registration year but no idea what a GDB is.

What a chassis code actually identifies

A chassis code is the platform designation the manufacturer used when the car was engineered. Toyota's GSE20, Honda's FD1, Subaru's GDB, BMW's E90 — each one pins down a specific body, a specific strut tower geometry and a specific hub carrier. That is exactly the set of variables a coilover kit has to match:

• Strut length and insert diameter — the damper body has to sit in the factory tube or replace it cleanly.
• Top mount bolt pattern — three bolts, two bolts, offset camber plates; a mismatch here means drilling, which no distributor wants to explain to a customer.
• Spring seat and rate — the same shell can carry very different corner weights depending on engine and drivetrain.
• Brake line and sensor brackets — small stamped parts, but a missing ABS bracket turns a two-hour job into a four-hour job.

The three mistakes that cause returns

1. Trusting the model name

"Golf 7" is not one car. The standard car, the GTI, the R and the estate differ in spring rate and, in some cases, in strut design. If your supplier quotes a kit for "Golf 7" with no chassis qualifier, the quote is incomplete — ask for the platform code it was built against.

2. Reading the year range as a model year

The year column on a fitment chart is the production range of that chassis, not the model year stamped on a particular vehicle. Facelifts often keep the same chassis and the same kit; a platform change often happens mid-model-year. A car registered in 2007 can perfectly well be a 2006 chassis. Always confirm with the code stamped on the car — usually on the firewall plate, the strut tower or the door jamb.

3. Ignoring the market

The same chassis sold in different regions can carry different top mounts and different brake hardware. A kit built for a Japanese-market car may not fit a European-market car of the same code. This is the single most common cause of "it almost fits" complaints, and it is why a serious factory asks which market the car was sold in before it confirms an order.

How to answer a customer who only knows the year

1. Ask for the chassis code — it is on the VIN plate, and it is often the first four to six characters of the VIN itself for Japanese and European cars.
2. Ask for a photo of the front strut top — three bolts in a triangle, two bolts, or a camber plate tell you almost everything.
3. Ask which market the car was sold in — JDM, EUDM, USDM.
4. Quote the item number, not the model name — on a purchase order, a model name is a hope; an item number is a specification.

Reading our own chart

Our coilover fitment guide lists 318 chassis-coded applications across 24 brands, ordered by chassis code with the factory item number for each row. The item number is what the factory builds and quotes against, so it is also what belongs in an RFQ. Slashes in the chassis column mean one kit covers both codes.

If a chassis is not on the list, that does not mean it cannot be built — it means it is not a standard stocked application. Send the code, year and market, and the factory will confirm whether it is available as a standard build or needs tooling as part of an OEM programme.

FAQ

Does a coilover kit fit every version of a model?

No. Kits are built per chassis code. Within one chassis, trim level usually does not change fitment; a different chassis, a different drivetrain layout or a different market can.

Can I fit a kit from a different chassis with modification?

Sometimes, but it is a fabrication job, not an installation: strut tops get drilled, brackets get cut, and geometry changes in ways the spring rates were never calculated for. For a workshop building a one-off car that may be acceptable. For a distributor shipping to customers it is a return waiting to happen.

What information should I put in an enquiry?

Chassis code, model years, market, quantity per item number, and whether you need your own branding on the kit. With those four things a factory can quote without a round of questions.