Genuine Mazda Alternator Adjuster Tensioning Bolt – 80mm • 99795-0880

Genuine Mazda Alternator Adjuster Tensioning Bolt – 80mm

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

This long adjustment bolt threads through the alternator adjuster spacer block and is used to move the alternator through its adjustment range. Moving the alternator changes the tension of the alternator and water-pump auxiliary drive belt.

Once the correct belt tension has been established, the alternator pivot and locking hardware secure the alternator in position. A seized, bent or damaged adjustment bolt can make belt adjustment difficult and may prevent the correct tension from being achieved.

One adjustment bolt is fitted per vehicle, and this listing supplies one Genuine Mazda bolt. The spacer block, locking bolt, lower pivot bolt and drive belt are supplied separately.

Important fitment restriction: This bolt fits the alternator adjustment arrangement used on Mk1 NA 1.8 and Mk2/Mk2.5 models. The Mk1 NA 1.6 uses a different adjustment bolt, spacer block and associated hardware.

• Part type: Alternator adjuster tensioning bolt
• Common names: Alternator tensioner bolt / belt-adjustment bolt / long adjuster bolt
• Mazda catalogue description: Bolt
• Location: Upper alternator adjustment mechanism
• Function: Moves the alternator to set auxiliary-drive-belt tension
• Nominal length: Approximately 80mm
• Quantity fitted per vehicle: 1
• Quantity supplied: 1 bolt
• Adjuster spacer block included: No
• Spacer-block locking bolt included: No
• Lower alternator pivot bolt included: No
• Alternator included: No
• Drive belt included: No
• Brand: Genuine Mazda
• Part No.: 99795-0880
• MX-5 fitment: Mk1 NA 1.8 and all Mk2/Mk2.5 NB models

Typical reasons for replacement:

• Adjustment bolt seized through corrosion
• Threads stripped, damaged or cross-threaded
• Bolt bent through excessive adjustment force
• Bolt head rounded during removal
• Original bolt fractured or missing
• Alternator replacement or refurbishment
• Adjuster spacer-block replacement
• Drive-belt tension cannot be adjusted correctly

Fitment advice: Confirm that the vehicle uses the Mk1 1.8 or Mk2/Mk2.5 alternator adjustment arrangement. Do not order this bolt for a standard Mk1 1.6 system, which uses different adjustment hardware.

Replacement advice: Inspect the adjuster spacer block, its internal threads, the spacer-block locking bolt, alternator bracket and lower pivot bolt before installation. A replacement adjustment bolt will not correct damaged spacer-block threads or a distorted bracket.

Adjustment advice: Loosen the alternator pivot and locking hardware before turning the adjustment bolt. Attempting to force the alternator while the locking fasteners remain tight can bend the bolt or damage the spacer block.

Other items to consider: Inspect the alternator and water-pump drive belt for cracking, glazing, fraying or contamination. Check the alternator bearings, water-pump pulley, crankshaft pulley and all associated mounting hardware.

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

Difficulty guide: DIY Difficulty: Easy to Moderate. Access is generally straightforward, although seized adjustment hardware may require careful dismantling.

Why Genuine Mazda? Genuine Mazda alternator adjustment hardware matches the original bolt length, thread specification and head dimensions. Correct geometry allows the bolt to pass through the spacer block and move the alternator through its intended adjustment range.

What’s in the box: One Genuine Mazda alternator adjuster tensioning bolt, part number 99795-0880.

Installation notes: Disconnect the battery before working around the alternator. Loosen the lower pivot bolt and upper spacer-block locking bolt before removing or turning the adjustment bolt. Inspect and clean the spacer-block threads, then install the new bolt by hand to avoid cross-threading. Adjust the alternator until the drive belt reaches the specified tension, tighten the pivot and locking hardware using the applicable Mazda procedure, and recheck belt alignment and tension after installation.