Genuine Mazda Rear Differential Cover Bolt • 9945-41-025

Genuine Mazda 9945-41-025 Rear Differential Cover Bolt

Replacement Genuine Mazda rear differential cover bolt for Mazda MX-5 Mk3, Mk3.5 and Mk3.75 NC models.

This bolt passes through the removable rear differential cover and threads into the main differential housing. Together with the remaining cover bolts, it clamps the cover and sealing joint evenly against the casing.

The rear cover encloses the differential gears and retains the differential oil. Correctly fitted cover hardware is therefore important for maintaining even clamping pressure around the joint and helping prevent lubricant leakage.

Eight bolts are used around the MX-5 NC differential rear cover. This listing supplies one Genuine Mazda bolt, so select the required quantity according to the repair being carried out.

Replacement should be considered where the original bolt is heavily corroded, seized, rounded, cross-threaded, stretched or damaged during differential dismantling.

• Part type: Rear differential cover bolt
• Primary use: Secures the removable rear cover to the differential housing
• Location: Rear face of the differential casing
• Quantity fitted per MX-5 NC differential: 8
• Quantity supplied: 1 bolt
• Rear cover included: No
• Gasket or sealant included: No
• Brand: Genuine Mazda
• Part No.: 9945-41-025
• Also referenced as: 994541025
• MX-5 fitment: Mk3, Mk3.5 and Mk3.75 NC models
• Additional application: Selected Mazda RX-8 differential assemblies

Fitment advice: This bolt is confirmed for the MX-5 NC rear differential cover. Mazda uses the same fastener reference in several other mounting and bracket applications, so confirm the original fixing position before installation.

Other items to consider: Inspect the remaining seven cover bolts, differential rear cover, casing threads, sealing faces, differential breather, drain and filler plugs and the condition of the differential oil. The cover joint will require the sealing method specified for the applicable differential.

Useful tools / consumables: Suitable socket and ratchet, calibrated torque wrench, drain container, gasket scraper or plastic cleaning tool, lint-free cloths, suitable degreaser, Mazda-specified sealant where required and the correct differential oil.

Difficulty guide: DIY Difficulty: Moderate to Advanced. Replacing an accessible bolt is straightforward, but removing and resealing the differential cover requires the oil to be drained and the joint surfaces to be prepared carefully. The differential may require additional support depending on the work being undertaken.

Why Genuine Mazda? Genuine Mazda differential hardware is manufactured to match the original thread, bolt length, head dimensions and strength specification required by the differential casing. Correct hardware helps maintain even cover clamping and compatibility with the original housing threads.

What’s in the box: One Genuine Mazda rear differential cover bolt, part number 9945-41-025.

Installation notes: Drain the differential oil before removing the rear cover. Clean the bolt holes, cover and housing sealing faces without allowing debris to enter the differential. Apply the specified gasket or sealant arrangement, position the cover squarely and start all bolts by hand. Tighten the bolts progressively and evenly in the Mazda workshop sequence to the specified torque. Allow any sealant to cure as directed before refilling with the correct differential oil, then inspect the cover joint for leakage.