How to choose springs for BMW cars?

BMW driver question – differences in suspension springs

I have a question about suspension springs. What is the difference between C1 springs and, for example, C4 springs? I am getting ready to replace them and would like to know how they differ. I’ve searched the Internet and can’t find a concrete answer. What is it about these designations?

The problem was with a 2006 BMW 118i E87, but it can also happen with other models.

BM Cars service answer – how to select BMW suspension springs?

Selecting springs on BMW cars is a task that requires knowledge and use of the original manufacturer’s documentation. In the ETK parts catalog, after selecting a specific vehicle (by VIN number), only if we connect online with the BMW database can we select the right springs.

This uses the statement of the original equipment of the vehicle when it left the factory. The matched springs have only the eleven-digit BMW part number designations. The original spring also lacks any other markings (except the factory sticker with the part number).

The selection of springs from a replacement should be made using the full vehicle data. In this case, we have no guarantee that the catalog of the supplier of the replacement correctly selects the springs. Very rarely it is possible to “scross” (combine) the number of the original BMW spring with the number of the replacement.

Springs, like other vehicle suspension components, should be replaced in pairs on one axle. The best results are obtained by replacing a set of springs with new original ones.

Any attempt to change the springs to something other than the original ones (more hardened, sporty, lowered, etc.) carries the risk of poor selection and the resulting consequences. More difficult handling, suspension that is too low or too high, rubbing of wheels against body components, etc.

The designations of C1, C4 springs cited by you in your question are not clear and do not allow you to determine their type, manufacturer and characteristics.

If you want to avoid unpleasant surprises in the operation of your vehicle, we advise you to choose the right spare parts.

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