{"product_id":"537185801-t35-trimmer-head-bump-knob-4pack","title":"537185801 Bump Knob - Fits Husqvarna T35 Trimmer Head (2003-05, 2005-01, 2007-04) - 4 Pack","description":"\u003ch2\u003e537185801 Bump Knob Replacement\u003c\/h2\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eHigh-Impact Blue Polymer:\u003c\/strong\u003e Manufactured from a high-density, abrasion-resistant plastic specifically designed to withstand thousands of high-velocity \"bumps\" against asphalt, gravel, and packed soil.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eReinforced Structural Ribbing:\u003c\/strong\u003e The internal geometry features reinforced walls to prevent the knob from cracking or shattering under the extreme centrifugal force of commercial-grade trimmers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrecision Spring Seating:\u003c\/strong\u003e Engineered with a centered internal recess to perfectly secure the T35's heavy-duty spring, ensuring a consistent and responsive line-advancement \"snap\" every time.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCommercial-Grade Multi-Pack:\u003c\/strong\u003e This 4-piece kit provides a cost-effective solution for landscaping fleets and large residential properties, ensuring you always have a spare on hand to prevent downtime.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSnap-In Tool-Free Installation:\u003c\/strong\u003e Designed as a direct-fit replacement that clicks into the existing T35 housing by hand, allowing for rapid field repairs without the need for specialized tools.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eReplaces \/ Cross-Reference Part Numbers\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e537185801\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCompatibility \u0026amp; Fitment\u003c\/h3\u003e\n\u003cp\u003eThis bump knob is the standard replacement for the professional \"T35\" series trimmer heads. Key compatible models include:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eHusqvarna 100\/200 Series:\u003c\/strong\u003e 123L, 123LD, 225L, 232L, 232R.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHusqvarna 300 Series:\u003c\/strong\u003e 322L, 323L, 324Lx, 325L, 325Lx, 326L, 326Lx, 327LS.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHusqvarna 500 Series:\u003c\/strong\u003e 522L, 525L, 525LS, 525LST, 535LS.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHistorical Production Dates:\u003c\/strong\u003e Compatible with T35 heads manufactured during the 2003-05, 2005-01, and 2007-04 production cycles.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNote:\u003c\/strong\u003e Specifically for the T35 head. If you have the smaller T25 or larger T45, this knob will not fit correctly.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhen to Replace\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eWorn-Through Bottom:\u003c\/strong\u003e The center of the blue knob has ground down from pavement contact to the point where the internal metal spring is visible or falling out.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBroken Retaining Tabs:\u003c\/strong\u003e The plastic clips that lock the knob into the housing have snapped, causing the knob to fly off while the trimmer is spinning at high RPM.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSeized Mechanism:\u003c\/strong\u003e Significant buildup of dried sap, dirt, and debris has fused the knob to the internal spool, preventing it from releasing new line.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRounded Indexing Teeth:\u003c\/strong\u003e The internal plastic \"teeth\" that click against the spool have rounded off, causing the head to dump all the line at once during use.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVisible Stress Fractures:\u003c\/strong\u003e White lines or cracks appearing in the blue plastic, indicating the material has become brittle and is prone to catastrophic failure.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation Tips\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eClean the Housing:\u003c\/strong\u003e Before installing the new knob, use a stiff brush or screwdriver to remove all dried grass and mud from the locking slots and spring area to ensure a 100% secure lock.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInspect the Spring:\u003c\/strong\u003e Ensure the internal metal spring is not rusted or collapsed. If the spring is weak, the new knob will stay \"compressed,\" causing the line to feed uncontrollably.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSnap-Lock Check:\u003c\/strong\u003e Press the new knob firmly into the housing until you hear a distinct \"click\" on both sides. Give the knob a firm tug by hand to verify it is fully seated before starting the engine.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManual Feed Test:\u003c\/strong\u003e With the engine off, press the knob in and pull the trimmer line manually to ensure the indexing mechanism is releasing the line smoothly.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAvoid \"Riding\" the Head:\u003c\/strong\u003e To maximize the life of your new knobs, try to avoid letting the trimmer head drag on the ground while trimming; only make contact with the surface when you need to advance the line.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"BlueStarsParts","offers":[{"title":"Default Title","offer_id":45213787652285,"sku":"AZ00102896","price":15.03,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/2576\/7548\/files\/AZ00168815_1_308c4fb3-dde2-45ff-b79e-4f9d27f36fb1.jpg?v=1762247019","url":"https:\/\/bluestarsparts.com\/products\/537185801-t35-trimmer-head-bump-knob-4pack","provider":"BlueStars Parts","version":"1.0","type":"link"}