{"product_id":"mercury-mercruiser-lockwasher-312-24-39107","title":"Mercury MerCruiser Lockwasher 5\/16-24 (0.312-24) 39107","description":"\u003ch2\u003eMercury MerCruiser Lockwasher — 5\/16-24 (0.312-24) \/ 39107\u003c\/h2\u003e\n\n\u003ctable\u003e\n\u003ctr\u003e\n\u003cth\u003eField\u003c\/th\u003e\n\u003cth\u003eDetail\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePart Number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e39107 \/ 13-39107\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBrand\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eMercury Marine \/ MerCruiser\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eOfficial Product Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eLockwasher — OEM Marine Hardware\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eThread \/ Size Spec\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0.312-24 (5\/16 inch diameter, 24 threads per inch — fine thread)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSupersedes\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eNone on record\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eReplaced By\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eNo supersession confirmed — 39107 remains an active Mercury part\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSystem\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eHardware \/ Fasteners — used where the Mercury parts diagram specifies this lockwasher\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSold As\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eIndividually — confirm quantity required from your parts diagram\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eWeight (approx.)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0.02 kg \/ 0.7 oz\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eWhat This Part Does\u003c\/h3\u003e\n\u003cp\u003eThe 39107 is a genuine Mercury OEM lockwasher sized to the 5\/16-24 fine-thread specification (0.312 in. diameter, 24 threads per inch). Lockwashers are used under fastener heads or nuts at positions where vibration, heat cycling, or operational loads could cause fastener loosening. Using the OEM-specified lockwasher ensures the correct fit, material grade, and locking tension for the assembly shown in the Mercury parts diagram.\u003c\/p\u003e\n\n\u003ch3\u003eCompatible Applications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eMercury MerCruiser engine, sterndrive, and marine assembly positions where the factory parts diagram specifies part number 39107 \/ 13-39107\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eConfirm fitment using the specific Mercury parts diagram for your engine or drive model and serial number. The 0.312-24 spec identifies the thread diameter and pitch — verify this matches the fastener and mating thread at the installation position before ordering.\u003c\/p\u003e\n\n\u003ch3\u003eSerial Number \u0026amp; Fitment Notice\u003c\/h3\u003e\n\u003cp\u003eConfirm the assembly, engine model, and serial number against the applicable Mercury parts diagram before ordering. Mercury uses multiple lockwasher sizes across engine and drive assemblies — confirm 39107 is specified at the exact fastener position in your diagram.\u003c\/p\u003e\n\n\u003ch3\u003eDimensions\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eThread spec:\u003c\/strong\u003e 0.312-24 (5\/16 in. diameter × 24 TPI, fine thread)\u003c\/li\u003e\n\u003cli\u003eExact inside diameter, outside diameter, and thickness per Mercury OEM specification — confirm against diagram for your application\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhen to Replace\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eLockwasher is deformed, flattened, or cracked\u003c\/li\u003e\n\u003cli\u003eLocking tabs or serrations are worn smooth\u003c\/li\u003e\n\u003cli\u003eSigns of corrosion, pitting, or stress damage\u003c\/li\u003e\n\u003cli\u003eFastener is being removed and reinstalled as part of a service procedure — replace as a matter of course\u003c\/li\u003e\n\u003cli\u003eMercury service procedure specifies new hardware on reassembly\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eOEM lockwashers should generally not be reused after removal in assemblies where fastener retention is critical to safe operation.\u003c\/p\u003e\n\n\u003ch3\u003eService Interval\u003c\/h3\u003e\n\u003cp\u003eNo fixed replacement interval applies. Replace whenever the associated fastener is removed during service, or whenever the lockwasher shows deformation, corrosion, or loss of locking function. Follow the applicable Mercury service manual for torque specifications at the installation position.\u003c\/p\u003e\n\n\u003ch3\u003eInstallation Notes\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eConfirm the fastener thread spec (5\/16-24 fine thread) matches the installation position\u003c\/li\u003e\n\u003cli\u003ePlace the lockwasher between the fastener head or nut and the mating surface as shown in the Mercury diagram\u003c\/li\u003e\n\u003cli\u003eDo not reuse a lockwasher that has been compressed, deformed, or corroded\u003c\/li\u003e\n\u003cli\u003eFollow Mercury’s specified torque value for the fastener at this position\u003c\/li\u003e\n\u003cli\u003eInspect the mating thread and fastener condition before reassembly\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eAlternate \u0026amp; Superseded Part Numbers\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e39107\u003c\/strong\u003e — Mercury \/ MerCruiser OEM number\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e13-39107\u003c\/strong\u003e — Mercury catalog prefix format\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eNo superseding number is confirmed. 39107 remains listed as an active Mercury part.\u003c\/p\u003e\n\n\u003ch3\u003eTechnical FAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eQ: What does 0.312-24 mean?\u003c\/strong\u003e\u003cbr\u003e\nA: It is the thread specification for the fastener this lockwasher is designed for — 0.312 inches (5\/16 in.) in diameter with 24 threads per inch (fine thread). Confirm this matches the fastener at your installation position before ordering.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: Do I need to replace this lockwasher every time I remove the fastener?\u003c\/strong\u003e\u003cbr\u003e\nA: As a general practice, yes — especially in assemblies where fastener retention is safety-critical. A lockwasher that has been fully compressed once may not provide the same locking tension when reinstalled. At $2–3 each, replacement is inexpensive insurance on a rebuilt assembly.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: Can I use a generic 5\/16-24 lockwasher instead?\u003c\/strong\u003e\u003cbr\u003e\nA: Only if it matches the OEM material grade and dimensions specified for the installation. Mercury OEM hardware is manufactured to specific material and dimensional standards. When in doubt, use the OEM part number to ensure correct fit.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eQ: How many do I need?\u003c\/strong\u003e\u003cbr\u003e\nA: Check the quantity shown in the Mercury parts diagram for your specific assembly — this listing is sold individually. Order the quantity indicated in the diagram.\u003c\/p\u003e\n\n\u003chr\u003e\n\u003ch3\u003eParts Desk Insights\u003c\/h3\u003e\n\u003cp\u003eLockwashers like 39107 are the kind of part customers often forget to order until they’re mid-service with the fastener already out. The best time to order this is before the assembly comes apart — check the diagram for the quantity required and order them with the primary service parts. The main thing to confirm is that the 0.312-24 fine-thread spec matches the fastener at the installation position, as Mercury uses several different lockwasher sizes across engine and drive assemblies and they can look nearly identical.\u003c\/p\u003e","brand":"MERC","offers":[{"title":"Default Title","offer_id":43563856494628,"sku":"39107","price":2.26,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0743\/5799\/7604\/files\/d3c1f7b7-91b6-489f-99ac-616bad8ddabc.png?v=1789168464","url":"https:\/\/marisolmarine.com\/products\/mercury-mercruiser-lockwasher-312-24-39107","provider":"Marisol Marine Company","version":"1.0","type":"link"}