{"product_id":"ohlins-o-ring-72-75x1-78-nbr70-00638-51","title":"Öhlins O-ring 72.75x1.78 NBR70 – 00638-51","description":"\u003cp\u003eO-ring 72.75x1.78 NBR70, Öhlins part number 00638-51. A ring that has taken a set no longer springs back and starts to weep under pressure.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eInner Diameter 72.75 mm\u003c\/li\u003e\n\u003cli\u003eOriginal Öhlins service part\u003c\/li\u003e\n\u003cli\u003eÖhlins part number 00638-51\u003c\/li\u003e\n\u003cli\u003eMaterial NBR 70\u003c\/li\u003e\n\u003cli\u003eCross Section 1.78 mm\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eFunction\u003c\/h2\u003e\u003cp\u003eDimensionally this is 72.75 mm, 1.78 mm, NBR 70, which is how it is told apart from the rest of the range. Öhlins specifies the compound by position: NBR where oil is the concern, FKM where heat is. An oil seal that has hardened lets the shaft pass oil past it, and the damping fades long before the leak becomes visible. O-rings are single-use in a pressurised damper — they are replaced whenever the unit is opened.\u003c\/p\u003e\u003ch2\u003eGenuine Service Part\u003c\/h2\u003e\u003cp\u003eÖhlins publishes dimensions for its service parts so a workshop can verify before it fits. This is an original Öhlins part, not an aftermarket equivalent — the tolerances are the ones the unit was assembled to. Order by part number — descriptions repeat across sizes, numbers do not. Öhlins numbers do not follow a logic you can guess — always read them from the documentation.\u003c\/p\u003e\u003ch2\u003eIdentifying the Right Part\u003c\/h2\u003e\u003cp\u003ePart number 00638-51 is unambiguous; the description alone is not, because Öhlins uses similar wording across sizes. inner diameter 72.75 mm, cross section 1.78 mm, material NBR 70 is what distinguishes this number from its neighbours in the range. Öhlins uses seals with a spring-loaded lip so they follow the shaft as it wears. A ring that has taken a set no longer springs back and starts to weep under pressure.\u003c\/p\u003e\u003ch2\u003eFitting and Setup Service\u003c\/h2\u003e\u003cp\u003eÖhlins recommends that its units are serviced by an authorised centre. We are one: rebuild, revalve and setup all happen in our own workshop.\u003c\/p\u003e\u003ch2\u003eSpecifications\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cem\u003eBrand:\u003c\/em\u003e Öhlins\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003ePart Number:\u003c\/em\u003e 00638-51\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eCategory:\u003c\/em\u003e O-Rings\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eInner Diameter:\u003c\/em\u003e 72.75 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eCross Section:\u003c\/em\u003e 1.78 mm\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eMaterial:\u003c\/em\u003e NBR 70\u003c\/li\u003e\n\u003cli\u003e\n\u003cem\u003eCountry of Origin:\u003c\/em\u003e Sweden\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Öhlins","offers":[{"title":"Default Title","offer_id":53648923492618,"sku":"00638-51","price":5.9,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0949\/7831\/0410\/files\/00638-51_60af6296-9036-482a-b97f-22d90319839f.png?v=1788872628","url":"https:\/\/inter-pace.com\/products\/ohlins-o-ring-72-75x1-78-nbr70-00638-51","provider":"Inter-Pace","version":"1.0","type":"link"}