The Karcepts ND Front Subframe Reinforcement Kit has been developed to solve subframe tearing issues observed by racers who have been competing with their ND Miatas on the soft factory springs (SCCA Solo C Street Class is one example using this rule set).
For optimal speed on track, competitors have been using front sway bar rates 4-5 times stiffer than factory. Couple a super stiff sway bar with soft springs and you generate a high amount of loading through the subframe. Also factor in the ND's subframe being constructed of very thin sheet metal (only 2mm thick) with overhung sway bar mounting locations, and you have a recipe for disaster.
Karcepts has been able to come up with billet aluminum inserts to seat within the pockets of the subframe and prevent the tearing failures. These reinforcement pieces are bolted in securely with large 10mm, 12mm, and 14mm hardware. Installation is simple and will not require tedious subframe removal. If utilizing a Karcepts ND Front Sway Bar Kit, this reinforcement package additionally integrates a clamping feature with the Karcepts Sway Bar Mounts.
No known subframe tears have been observed on vehicles using stiffer spring rate setups at this time.
View the installation instructions for any potential install/fitment questions you may have: KFSR-ND Installation Instructions