{"product_id":"gs090-pinion-gear-21t","title":"GS090 Pinion Gear 21T","description":"\u003ch2\u003eCEN GS090 PINION GEAR – 21T\u003c\/h2\u003e\u003cp\u003eThe \u003cstrong\u003eCEN Racing GS090 Pinion Gear\u003c\/strong\u003e is the \u003cstrong\u003e21-tooth transmission pinion gear\u003c\/strong\u003e used in compatible CEN 2-speed driveline systems. Historical CEN parts documentation and multiple current specialist listings identify GS090 as the 21T pinion, while GS092 is the dogbone\/drive shaft part number.\u003c\/p\u003e\u003ch3\u003eVERIFIED PRODUCT DATA\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e CEN Racing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e GS090\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eComponent Type:\u003c\/strong\u003e Transmission Pinion Gear\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTooth Count:\u003c\/strong\u003e 21T\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTransmission Role:\u003c\/strong\u003e 2-speed pinion gear in compatible CEN driveline assemblies\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003ePART-NUMBER CLARIFICATION\u003c\/h3\u003e\u003cp\u003eSome current reseller\/catalog pages incorrectly label GS090 as a dogbone, but original CEN manuals and current specialist parts listings consistently identify \u003cstrong\u003eGS090 as the 21T pinion gear\u003c\/strong\u003e. The corresponding dogbone is \u003cstrong\u003eGS092\u003c\/strong\u003e. GASHEAD RC uses the technically documented CEN part-number assignment here to avoid a fitment error.\u003c\/p\u003e\u003ch3\u003e2-SPEED GEARING ROLE\u003c\/h3\u003e\u003cp\u003eIn the CEN 2-speed transmission system, GS090 works as the \u003cstrong\u003e21T pinion\u003c\/strong\u003e and pairs within the same gearbox family as the GS089 17T pinion and GS087\/GS088 steel spur gears. Tooth count directly affects transmission ratio and gear engagement, so GS090 should not be substituted with another pinion tooth count unless the complete gear pairing and transmission setup are known to be compatible.\u003c\/p\u003e\u003ch3\u003eGEAR MESH \u0026amp; SHIMMING\u003c\/h3\u003e\u003cp\u003eCEN service documentation emphasizes correct gear alignment and spacing in these 2-speed assemblies. Improper mesh can chip or damage spur gears and increase noise, friction and bearing load.\u003c\/p\u003e\u003cul\u003e\n\u003cli\u003eVerify the mating spur gear is the correct part and tooth count.\u003c\/li\u003e\n\u003cli\u003eCheck shims\/spacers are installed in the correct positions.\u003c\/li\u003e\n\u003cli\u003eConfirm the gear rotates freely with no tight spots through a full revolution.\u003c\/li\u003e\n\u003cli\u003eDo not run a fresh pinion against a badly damaged spur gear.\u003c\/li\u003e\n\u003cli\u003eInspect clutch-bell bearings and shaft play before finalizing mesh.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eWEAR PATTERN DIAGNOSIS\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eTooth-tip polishing or chipping:\u003c\/strong\u003e may indicate excessive backlash or insufficient engagement.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHeavy whine:\u003c\/strong\u003e can indicate overly tight mesh.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRhythmic clicking:\u003c\/strong\u003e can indicate a chipped tooth, eccentric rotation or damaged mating gear.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUneven wear across the face:\u003c\/strong\u003e can point to shaft misalignment or bearing play.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eINSTALLATION CHECKLIST\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eConfirm the application calls for CEN GS090 \/ 21T.\u003c\/li\u003e\n\u003cli\u003eInspect GS087\/GS088 or the applicable mating spur for damage before reuse.\u003c\/li\u003e\n\u003cli\u003eCheck clutch-bell or supporting bearings for play.\u003c\/li\u003e\n\u003cli\u003eInstall the correct shims and spacers for the gearbox configuration.\u003c\/li\u003e\n\u003cli\u003eSet mesh so the gear train rotates freely without excessive backlash.\u003c\/li\u003e\n\u003cli\u003eRotate by hand before starting the engine or motor.\u003c\/li\u003e\n\u003cli\u003eReinspect gear contact after the first operating session.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003eWHAT CEN DOES NOT PUBLISH\u003c\/h3\u003e\u003cp\u003eThe available CEN documentation identifies GS090 as a \u003cstrong\u003e21T pinion gear\u003c\/strong\u003e, but does not provide a complete current specification set for pitch\/module, outside diameter, face width, bore diameter or pressure angle. GASHEAD RC does not invent those dimensions. Match the part by the exact GS090 designation and compatible transmission documentation.\u003c\/p\u003e\u003ch3\u003eGASHEAD RC NOTE\u003c\/h3\u003e\u003cp\u003eThis listing was corrected from an erroneous “Dogbone” description. For this part number, the technically supported identity is \u003cstrong\u003eGS090 = 21T Pinion Gear\u003c\/strong\u003e. If you need the corresponding dogbone, reference \u003cstrong\u003eGS092\u003c\/strong\u003e instead.\u003c\/p\u003e","brand":"CEN Racing","offers":[{"title":"Default","offer_id":48361990258740,"sku":"coz1789726973745","price":8.18,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0764\/0180\/3316\/files\/gs090-pinion-gear-21t_1.webp?v=1789726983","url":"https:\/\/woodbuttonwarmclad.shop\/products\/gs090-pinion-gear-21t","provider":"My Store","version":"1.0","type":"link"}