Genuine Mazda Rear Subframe Brace Bar Kit • MX-5 MK3/NC (06-15)

Genuine Mazda Rear Subframe Brace Bar and Bolts Kit

Genuine replacement rear subframe brace bar and bolts 8 piece kit for Mazda MX-5 Mk3 / Mk3.5 / Mk3.75 (NC) models listed in the compatibility table.

The rear subframe brace bars are fitted underneath the rear of the vehicle and helps tie the rear subframe area back into the main body structure. It supports chassis rigidity around the rear suspension/subframe mounting area and helps maintain the factory structure that Mazda designed into the NC platform.

There are typically two rear subframe brace bars using 6 fasteners fitted per vehicle which this kit covers. They sit diagonally between the rear subframe area and the underside of the body/sill structure, one on each side of the car.

These items are commonly replaced when the original brace bar is heavily corroded, weakened, bent, damaged during underbody work, or no longer suitable for MOT/roadworthiness due to rust. On ageing MX-5 NC models these rear brace bars are a common corrosion point, especially on cars exposed to winter road salt, standing water or poor underside protection.

• Part type: Rear subframe brace bar / rear cross bar / underbody brace and bolt kit
• Primary use: Rear subframe-to-body bracing and chassis reinforcement
• Location: Rear underside of vehicle, between rear subframe and body/sill area
• Quantity per vehicle: 1 (Kit)
• Brand: Genuine Mazda
• Part No.: B00039
• Also referenced as: NE5128E90 / 99466-1225
• Designed for Mazda MX-5 Mk3 / Mk3.5 / Mk3.75 (NC) applications listed in the compatibility table

Fitment advice: Designed for the Mazda MX-5 NC variants listed in the compatibility table, covering Mk3, Mk3.5 and Mk3.75 soft-top and Roadster Coupe / PRHT models with 1.8L L8-DE and 2.0L LF-VE petrol engines. This is a rear underbody brace bar used as part of the rear subframe/body bracing arrangement, with two fitted per car.

Other items to consider: When changing this part, you may also want to consider purchasing related items such as other rear subframe hardware, penetrating fluid, rust treatment, cavity wax or underbody protection products. If both brace bars show corrosion, replacing them as a pair is usually the most sensible approach.

Useful tools / consumables: Vehicle lift or axle stands, socket set, breaker bar, torque wrench, penetrating fluid, wire brush, impact tools where suitable, rust treatment, underbody protection, safety glasses, gloves and workshop towels.

Difficulty guide: DIY Difficulty: Moderate. The brace bars are external underbody components and are generally accessible with the car safely raised, but corrosion and seized fixings can make removal more difficult. Correct support of the vehicle and careful handling of rusted fasteners is important.

Why Genuine Mazda? 

Genuine Mazda underbody brace components are designed to match the original specification of the vehicle. For a rear subframe brace bar kit, this means the correct length, mounting hole position, shape, strength and coating to work with the factory rear subframe and body mounting points. Genuine Mazda parts help maintain the intended fit and chassis structure without the fitment issues that can come from poorly made pattern parts.

What’s in the box: Two Genuine Mazda subframe brace bars with 6 Genuine Mazda bolts / fasteners.

Installation notes: Clean the mounting points before installation and treat any surrounding corrosion before fitting the new brace bar. Apply suitable corrosion protection after installation and tighten all fixings to Mazda workshop manual torque specifications.