{"product_id":"acl-subaru-ej20-ej22-ej25-for-thrust-in-5-position-002mm-os-high-performance-w-extra-oil-cl-1","title":"ACL High Performance Main Bearing Set | Subaru EJ20 \/ EJ22 \/ EJ25 | Thrust at #5 | Extra Oil Clearance | 5M8309HXO\/S2-STD","description":"\u003ch2\u003eACL High Performance Main Bearing Set – Subaru EJ20 \/ EJ22 \/ EJ25 | Thrust at #5 | Extra Oil Clearance | 5M8309HXO\/S2-STD\u003c\/h2\u003e\n\n\u003cdiv style=\"border-left: 4px solid #333; padding: 10px 16px; margin-bottom: 16px; background: #f9f9f9;\"\u003e\n\u003cp\u003e\u003cstrong\u003eEngine bearing — confirm journal size and housing bore before ordering.\u003c\/strong\u003e This is a main bearing set with thrust flanges at the #5 (rear) main bearing position — correct for EJ20\/EJ22\/EJ25 applications where the crankshaft thrust surface is at position 5. Confirm your crankshaft journal diameter and housing bore are standard (unmachined) before ordering this set — worn or machined journals require an undersize bearing. The part number suffix “STD” indicates standard journal sizing — cross-reference with ACL’s fitment chart if your application specifies an oversize outside diameter. Professional engine assembly and plastigage clearance verification required.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cp\u003eACL 5M8309HXO\/S2-STD high performance main bearing set for the Subaru EJ20, EJ22, and EJ25 flat-four engine family. Includes thrust-flanged shells at the #5 main bearing position to control crankshaft endplay. Extra oil clearance (HXO specification) for improved lubrication and cooling under high performance and high RPM conditions. 0.8 lbs. Ships fast across Canada and the US.\u003c\/p\u003e\n\n\u003ch3\u003eEJ Crankshaft Thrust Bearing — Why This Matters\u003c\/h3\u003e\n\u003cp\u003eThe Subaru EJ-series crankshaft uses the #5 (rearmost) main bearing position as its thrust bearing location — the pair of flanged half-shells that prevent forward and rearward crankshaft movement (endplay). Thrust bearing wear is a documented failure mode on the EJ platform, particularly on manual transmission vehicles where repeated clutch engagement applies rearward load on the crankshaft thrust face. Symptoms of excessive crankshaft endplay include:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eAudible knock or clunk during clutch engagement or release\u003c\/li\u003e\n\u003cli\u003eCrankshaft movement measurable with a dial indicator at the snout (beyond OEM specification, typically 0.05–0.15mm)\u003c\/li\u003e\n\u003cli\u003eIn severe cases, crankshaft contact with adjacent engine components leading to rapid bearing and journal damage\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eReplacing the #5 main bearing with a high-quality ACL unit restores correct endplay clearance and prevents further thrust face wear when paired with correct oil clearance and oil pressure.\u003c\/p\u003e\n\n\u003ch3\u003eHigh Performance Extra Oil Clearance — HXO Specification\u003c\/h3\u003e\n\u003cp\u003eACL’s “HXO” designation indicates this bearing set is manufactured to their High Performance specification with Extra Oil Clearance. In a production engine, OEM bearing clearances are set to minimise noise across the full operating temperature range, including cold starts. In a high-performance engine running at sustained high RPM and elevated oil temperatures, tighter OEM clearances can restrict oil film thickness and oil flow through the bearing:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eExtra oil clearance\u003c\/strong\u003e increases the oil film gap between the journal and bearing shell. This allows a greater volume of oil to flow through the bearing at operating pressure, improving both lubrication and heat removal from the bearing surface and journal.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePerformance application:\u003c\/strong\u003e Correct for built EJ engines running at elevated RPM, higher oil temps, or with high-volume oil pumps. Extra clearance bearings require adequate oil pressure to maintain the hydrodynamic oil film — confirm your oil system (pump, pressure relief) is appropriate for the clearance specification.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNot for all applications:\u003c\/strong\u003e In a stock-power, stock-oil-pressure EJ, standard-clearance bearings may be preferable. The HXO spec is optimised for performance builds where oil system capacity supports it.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eEJ20 \/ EJ22 \/ EJ25 Coverage\u003c\/h3\u003e\n\u003cp\u003eACL’s 5M8309HXO\/S2-STD covers the full EJ-series main bearing journal specification shared across the EJ20 (2.0L), EJ22 (2.2L), and EJ25 (2.5L) engine families. All three engines share the same crankshaft main journal diameter and #5 thrust position. The EJ25 family includes EJ251 (NA), EJ253 (NA), EJ255 (WRX turbo), and EJ257 (STI turbo) variants — confirm your specific variant’s journal diameter is unmachined before ordering the STD sizing.\u003c\/p\u003e\n\n\u003ch3\u003eJournal Sizing — STD\u003c\/h3\u003e\n\u003cp\u003eThe “STD” suffix indicates this bearing set is sized for standard (unmachined) crankshaft journal diameters. If your crankshaft journals have been turned undersize during a previous rebuild or to clean up damage, you will need an undersize bearing set (e.g. 0.025mm, 0.25mm undersize) — measure your journal diameters before ordering. Plastigage clearance verification during assembly is required to confirm oil clearance is within specification for this bearing set and your specific crankshaft.\u003c\/p\u003e\n\n\u003cp\u003e\u003cem\u003eMain bearing set — professional engine assembly required. Verify crankshaft journal size before ordering. Plastigage clearance check mandatory during assembly. Extra oil clearance spec — confirm oil system is appropriate for HXO clearance.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eBrand: ACL\u003c\/li\u003e\n\u003cli\u003ePart Number: 5M8309HXO\/S2-STD\u003c\/li\u003e\n\u003cli\u003eType: Main bearing set with thrust\u003c\/li\u003e\n\u003cli\u003eThrust position: #5 (rear main)\u003c\/li\u003e\n\u003cli\u003eSpecification: High Performance, Extra Oil Clearance (HXO)\u003c\/li\u003e\n\u003cli\u003eJournal sizing: STD (standard — unmachined journals)\u003c\/li\u003e\n\u003cli\u003eApplication: Subaru EJ20 \/ EJ22 \/ EJ25 — all variants\u003c\/li\u003e\n\u003cli\u003eWeight: 0.8 lbs\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"ACL","offers":[{"title":"Default Title","offer_id":51349814411431,"sku":"ACL5M8309HXO\/S2-STD","price":171.65,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0555\/8344\/1063\/files\/40122eef7c72ad8aedbf813a6911e74f_4443d586-3bee-48c5-b895-ade87c444c39.png?v=1789675874","url":"https:\/\/www.straightsiximports.com\/en-us\/products\/acl-subaru-ej20-ej22-ej25-for-thrust-in-5-position-002mm-os-high-performance-w-extra-oil-cl-1","provider":"Straight Six Imports","version":"1.0","type":"link"}