SM Rules Case Study 1: Coil-Over Kits

Case Study 1: Spec Miata Coil-Over Kits

This rule was a focus of ours after trying to put together a complete and more affordable Spec Miata Suspension kit for our customers years ago. It is comprised of mostly off-the-shelf products, such as Eibach springs and sway bars, Bilstein shocks, and a few OEM Mazda parts. All of which we could get within our wholesale distribution outlets. There were a few pieces that we couldn't get however, and one in particular that was a major kick in the gut in terms of pricing was the coilover sleeves and perches. These are simply threaded aluminum sleeves and spring perch collars that slip over the Bilstein shock and serve one purpose: to provide an adjustable mounting surface for the Eibach 2.5" race springs. 

This is where rule interpretation comes in handy, as reading the rules regarding the coilover sleeves offers two options, not just the one you think it does!

Here it is telling us that the coilover sleeves to be used are part number 0000-04-5402AW from the Mazdaspeed Motorsports catalog. Easy, right? Well here's where it pays off to continue reading the rest of the rule stating: The sleeves and perches may be replaced with parts of the same material and dimensions. You may ask: Why would you replace them? The part number I need to use is right there! Simple, because part number 0000-04-5402AW is a $411 part from Mazdaspeed Motorsports. "Ok, so what?" you say. Well, explore the part of the rule that says "may be replaced with parts of the same material and dimensions" and you'll find yourself surprised at the money you can save by going with a "part of the same material and dimensions", such as our 5X Racing 2.5" Coilover Kits for Bilstein Shocks, which are $125 a set as compared to $411, a total savings of $286. That's an entry fee to an SCCA regional race! Same dimensions, same material, same function, same part but not with the same part number, not so similar of a price though! 

Where this rule is "gray" is that it doesn't specifcally say you CAN or CANNOT use the 5X Racing coilover kit, but it opens the door to the use of other options with the wording of the rule.

Push this one step further and put yourself in the tech shed of a national championship race, with your shocks laying on the bench in front of the inspectors. This might never happen, but if it does, here's how the conversation might go:

  • Inspector: "This coilover sleeve doesn't look the same as the others"
  • You: "It isn't, it is not the one from Mazdaspeed Motorsports. It's from 5X Racing."
  • Inspector: "Well the rules don't say you can use the ones from 5X Racing, they give you a Mazdaspeed Motorsports part number to use in the rule. These are not legal"
  • You: "The rules say I can replace them with parts of the same material and dimensions. These are of the same material and dimensions as the Mazdaspeed Motorsports kit. They're legal"
    • Case closed. The inspectors don't like to be challenged and might get gruff with you, but in the end the rules don't specify exactly which parts you can use as replacements, just that they have to be of the same material and dimensions, which they are.