Genuine Mazda Alternator Lower Pivot Bolt • 99724-1000

Genuine Mazda Alternator Lower Pivot Bolt

Replacement Genuine Mazda lower alternator pivot bolt for Mazda MX-5 Mk1 NA 1.8 and Mk2/Mk2.5 NB models with 1.6- or 1.8-litre petrol engines.

This bolt passes through the lower mounting point of the alternator and secures it to the main alternator bracket. The lower mounting acts as the pivot point while the alternator position is adjusted to set the correct alternator and water-pump drive-belt tension.

Once the belt tension has been set, the pivot and adjuster hardware secure the alternator in position. A seized, bent, damaged or incorrectly sized pivot bolt can prevent the alternator from moving freely or remaining correctly aligned.

One lower pivot bolt is fitted per vehicle, and this listing supplies one Genuine Mazda bolt.

Important alternator restriction: This bolt is intended for the original-style alternator with a threaded lower mounting ear. Some replacement or aftermarket alternators have an unthreaded lower ear and require a longer through-bolt and retaining nut instead.

Important model restriction: The original Mk1 NA 1.6 alternator mounting system uses different lower mounting hardware. This listing is for Mk1 1.8 and Mk2/Mk2.5 applications.

• Part type: Lower alternator pivot bolt
• Common names: Alternator lower mounting bolt / alternator hinge bolt / alternator pivot fastener
• Mazda catalogue description: Bolt
• Location: Lower alternator mounting ear to alternator bracket
• Function: Secures the alternator while allowing belt-tension adjustment
• Quantity fitted per vehicle: 1
• Quantity supplied: 1 bolt
• Retaining nut included: No
• Alternator bracket included: No
• Alternator adjuster hardware included: No
• Alternator included: No
• Drive belt included: No
• Brand: Genuine Mazda
• Part No.: 99724-1000
• MX-5 fitment: Mk1 NA 1.8 and all Mk2/Mk2.5 NB models

Typical reasons for replacement:

• Original pivot bolt seized through corrosion
• Bolt head rounded during removal
• Threads damaged or cross-threaded
• Bolt bent, stretched or fractured
• Original fastener missing
• Alternator replacement or refurbishment
• Alternator mounting-bracket replacement
• Previously fitted non-standard hardware

Fitment advice: Confirm that the vehicle has the Mk1 1.8 or Mk2/Mk2.5 alternator mounting arrangement. Check that the alternator has the original threaded lower mounting ear before ordering.

Replacement advice: Inspect the lower alternator ear, mounting bracket and female threads before installation. A replacement bolt will not correct a cracked alternator casing, distorted bracket or damaged threaded mounting hole.

Other items to consider: Inspect the alternator adjuster block, adjustment bolt, bracket fasteners and alternator and water-pump drive belt. Check the crankshaft and water-pump pulleys for damage or misalignment.

Useful tools / consumables: Socket and spanner set, calibrated torque wrench, penetrating fluid, wire brush, thread-cleaning tools and suitable belt-tension measuring equipment.

Difficulty guide: DIY Difficulty: Easy to Moderate. Access is generally straightforward, although corrosion or damaged threads may make removal more involved.

Why Genuine Mazda? Genuine Mazda alternator mounting hardware matches the original bolt length, thread specification, shank dimensions and strength requirements. Correct hardware helps maintain alternator alignment and secure belt adjustment.

What’s in the box: One Genuine Mazda lower alternator pivot bolt, part number 99724-1000.

Installation notes: Disconnect the battery before working around the alternator. Support the alternator and loosen the upper adjustment hardware before removing the lower pivot bolt. Inspect and clean the threaded lower alternator ear and mounting bracket. Start the replacement bolt by hand to prevent cross-threading, then adjust the alternator until the drive belt reaches the specified tension. Tighten the pivot and adjustment hardware to the applicable Mazda specification and recheck belt alignment and tension after installation.