{"product_id":"stihl-drive-pinion-4243-640-2503","title":"STIHL Drive Pinion - 4243 640 2503","description":"\u003cdiv\u003e\n\u003cp\u003eThe STIHL Drive Pinion - 4243 640 2503 restores factory-spec rotational transfer between the crankshaft coupling and clutch assembly, maintaining precise timing under high-load cutting conditions.\u003c\/p\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003ePrecision-gear cut hardened steel construction matched to original tooth profile and module\u003c\/li\u003e\n\u003cli\u003eControlled backlash tolerance ensures stable engagement with the spur gear and drive sprocket\u003c\/li\u003e\n\u003cli\u003eHeat-treated contact surfaces resist scoring and pitting caused by prolonged friction cycles\u003c\/li\u003e\n\u003cli\u003eExact dimensional replication eliminates trial-and-error fitting during routine maintenance swaps\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eProduct Details\u003c\/h2\u003e\n\u003cp\u003eServing as the primary power transmission component within the saw’s drivetrain, this pinion transfers rotational force from the engine crankshaft outward through the centrifugal clutch mechanism. The unit incorporates ground bearing journals and a standardized interface compatible with STIHL master rollers and clutch drums. Proper function depends on matching the designated gear ratio and pitch circle diameter to prevent accelerated wear on the drive sprocket or secondary chain components.\u003c\/p\u003e\n\u003ch2\u003eCompatibility\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eManufactured to replace OEM reference 4243 640 2503 across relevant STIHL production runs\u003c\/li\u003e\n\u003cli\u003eFits platforms where factory service documentation specifies this drive pinion iteration\u003c\/li\u003e\n\u003cli\u003eConfirm mounting flange clearance, shaft diameter, and total tooth count prior to installation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e","brand":"STIHL","offers":[{"title":"Default Title","offer_id":58547733365117,"sku":"ST-4243 640 2503","price":21.58,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0565\/9190\/9056\/files\/4243-640-2503.webp?v=1786974219","url":"https:\/\/ripongroundcare.com\/products\/stihl-drive-pinion-4243-640-2503","provider":"Ripon Ground Care","version":"1.0","type":"link"}