Circuit Sports Rear Upper Leading Arms - Mazda Miata MX-5 Roadster ('2016+ ND)
Circuit Sports Adjustable Rear Upper Leading Arm is a direct replacement of the Mazda MX-5 Miata (ND) factory link: part #N243-28-20X. Our arm uses Teflon-lined spherical (pillow ball) Heim joints with steel spacers as well as high tensile strength carbon steel u-brackets to ensure that each arm is made for high quality as well as increased strength, precision, and longevity. Each part retains the qualities of the OEM unit but is designed on improving strength and allow for increased adjust ability in fine tuning. The body of the tubular arms are finished off in our signature Circuit Sports high-gloss blue powdercoat to help resist against rust, damage, stain and oxidation.
Rear OEM alignment specifications are relatively conservative and max out at just about -2* of camber at the eccentric cam bolt, with a max of about 7.0mm link movement. However when used in conjunction with our other ND arms/links, camber and toe can be further increased, decreased, and/or corrected with more precision depending on the application; whether it’s to increase traction, improve high-speed stability, or cornering effectiveness and speed. This allows for quicker and finer adjustments with more range without having to adjust the eccentric cam bolts, which means that the user can make more aggressive track adjustments and yet revert back to the previous configuration for street without changing baseline alignment settings. Circuit Sports recommends setting all arms/links to oem spec as a baseline before making adjustments and documenting the lengths as reference to your specific application and vehicle height (for easier recall and consistent adjustment).
Adjustment ranges from OE baseline:
- Lateral links +/- 15 mm
- Leading/trailing arms +/-20 mm
- Toe control arm +/- 15 mm
Recommended torque specs:
- Eccentric cam bolts 63-75 ft-lb
- Rear Upper Lateral Link, joint side bolt 48-57 ft-lb
- All other u-bracket and joint bolts 49-59 ft-lb