Genuine Mazda Rear Subframe Mounting Nut • H266-28-091

Genuine Mazda H266-28-091 Rear Subframe Mounting Nut

Replacement Genuine Mazda rear subframe mounting nut for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models.

This nut threads onto one of the main chassis studs and clamps the rear suspension subframe securely against the underside of the vehicle body.

The rear subframe supports the differential, suspension arms and associated rear-suspension components. Secure and correctly tightened mounting hardware is therefore important for maintaining the intended position of the complete rear suspension and drivetrain assembly.

A total of six mounting nuts are used on the MX-5 NC rear subframe. This listing supplies one Genuine Mazda nut, so select the required quantity according to the repair being carried out.

Replacement should be considered where the original nut is heavily corroded, seized, rounded, damaged or missing, or whenever the rear subframe has been removed for repair, refurbishment or replacement.

• Part type: Rear subframe mounting nut
• Primary use: Secures the rear suspension subframe to the chassis studs
• Location: Rear subframe-to-body mounting points
• Quantity fitted per vehicle: 6
• Quantity supplied: 1 nut
• Brand: Genuine Mazda
• Part No.: H266-28-091
• Also referenced as: H26628091
• Related Mazda references: B531-33-030 / B531-33-030B
• Fitment note: Confirmed for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models

Fitment advice: This nut is used on the principal rear-subframe chassis studs. Inspect the original stud, threads and mounting position before installation. Where corrosion has reduced the stud diameter or damaged the threads, replacing the nut alone may not provide a safe repair.

Other items to consider: Inspect the remaining five subframe mounting nuts, chassis studs, mounting washers where fitted, subframe bushes, differential mounts and the surrounding subframe structure. Corrosion should be cleaned and assessed before the assembly is refitted.

Useful tools / consumables: Suitable socket and breaker bar, penetrating fluid, torque wrench, wire brush, thread-cleaning tools, vehicle lift or axle stands and a transmission or subframe support jack where the assembly is being lowered.

Difficulty guide: DIY Difficulty: Moderate to Advanced. Replacing an accessible nut may be straightforward, but loosening or lowering the rear subframe requires the vehicle and subframe to be supported securely. Suspension alignment should be checked where the subframe position has been disturbed.

Why Genuine Mazda? Genuine Mazda mounting hardware is manufactured to match the original chassis stud thread, nut dimensions, flange profile and clamping specification. Correct fit helps maintain secure subframe attachment and compatibility with the original mounting arrangement.

What’s in the box: One Genuine Mazda rear subframe mounting nut, part number H266-28-091.

Installation notes: Support the vehicle and rear subframe safely before loosening any mounting hardware. Clean and inspect the chassis-stud threads and ensure the subframe is correctly seated against its mounting points. Start the nut by hand to avoid cross-threading, then tighten the mounting nuts progressively and evenly to the applicable Mazda workshop specification. Check rear-wheel alignment if the subframe has been loosened or repositioned.