King MC Polymer Coated Main Bearing Set (0.25mm Undersize) - NC MX-5 (06-15)

King MC series main bearing set, 0.25 mm undersize (King MB5442MC0.25), for the 2006-2014 Mazda MX-5 Miata (NC). The undersize shells are for a crankshaft whose main journals have been reground 0.25 mm below standard; a crankshaft still at standard size takes the Standard set. The set holds five pairs of shells for the five main journals.

• King MC version: an OE-replacement main bearing with a polymer coating (King's version line reads 'OE-Repl. Polymer')
• King lists the MC bearings as commonly used for start-stop and hybrid engines that endure continuous metal-to-metal contact
• Size: 0.25 mm undersize, for main journals reground 0.25 mm below standard. Have the machinist confirm the finished journal size before ordering
• Set contents: 5 pairs (10 shells). Positions 1, 2, 4 and 5 are 19.1 mm long; position 3 uses a longer 25.8 mm pair with a different upper shell
• Dimensions King publishes for this family (standard size): main journal 51.98-52.00 mm, main housing bore 57.02-57.04 mm, wall thickness 2.504 mm. King does not publish separate dimensions for each size
• King's size options for MB5442MC: Standard, 0.25mm, 0.5mm and 0.75mm. Measure the journals and oil clearance before choosing a size; King's catalog does not give a target clearance for this set

Fitment: Main bearings, all five journals. 2006-2014 Mazda MX-5 Miata (NC). King's catalog lists the Mazda MX-5 1.8L and 2.0L for 2005-2014; 2005 is the global launch year and is shown here as US model year 2006. King lists through 2014 and does not list 2015. King publishes the vehicle list for the MB5442MC family, and this part number is the 0.25 mm size option of that family. King does not list it for the 1990-2005 Miata and lists no MX-5 after 2014.

Part number: King MB5442MC0.25

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