When Did Harley-davidson Start Using 6-speed Transmissions?

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In 2006, Harley-Davidson (H-D) made 1 of its astir pivotal mechanical updates successful years. It was a displacement (pun intended) that saw H-D move from a five-speed to a six-speed transmission, introduced pinch nan Dyna family of motorcycles. Dubbed nan "Cruise Drive," this caller transmission was Harley's quiet gyration to connection a gearbox that promised smoother road miles and amended roll-on capacity while retaining nan brand's signature rumble. A twelvemonth later, for nan 2007 exemplary lineup, nan six-speed gearbox was rolled retired crossed astir each Big Twin motorcycles (barring nan Sportster and nan V-Rod).

The timing was nary mishap — nan transmission arrived to complement nan then-new Twin Cam 96 engine. This was a powerplant boasting higher torque and mid-range performance, pinch a torque output that was 11 lb-ft higher than nan Twin Cam 88 that it replaced. The added powerfulness wasn't nan main logic for a caller gearbox, but nan Cruise Drive transmission's other cog dropped road revs by 11% astatine road speeds, making long-distance cruising smoother and quieter. 

For riders utilized to nan acquainted five-speed hum, that added sixth cogwheel now promised to toggle shape nan freeway experience. Suddenly, Harley's road manners matched its muscle, and riders could agelong nan miles without stretching nan revs. Models for illustration the Pan America 1250 adventure-tourer – like each modern Harleys — besides characteristic a six-speed transmission.

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The six-speed H-D transmission really dates backmost further than astir group realize. Harley-Davidson first offered an optional six-speed transmission successful 1999 alongside nan Twin Cam 88 engine. Riders could besides bid nan setup arsenic portion of a capacity upgrade done accessory kits for immoderate 1998-2000 models.

That early gearbox was engineered for smoother powerfulness transportation connected high-torque builds, and later evolved into nan Screamin' Eagle Six-Speed Gearset — Harley's ain aftermarket bolt-on upgrade for nan Twin Cam 88 engine. The assembly was wholly re-engineered for spot and smoother operation. It featured a thicker chrome billet broadside door, which not only housed nan added cogwheel but besides reinforced nan transmission lawsuit without forcing riders to alteration exhaust layouts. 

Inside, nan gearset retained nan banal ratios for first done 5th but introduced a existent overdrive sixth pinch a ratio of 0.89:1, which helped driblet motor velocity by astir 250 rpm astatine 70 mph — astir an 11% reduction. On nan highway, it meant noticeably little vibration, reduced mechanical stress, and a quieter, much composed ride.

That early sensation of a sixth cogwheel group nan shape for Harley's existent leap guardant successful 2006-2007, erstwhile nan institution made nan Cruise Drive six-speed transmission modular crossed its Big Twin lineup, paired pinch nan Twin Cam 96. It featured helical-cut gears pinch cogwheel ratios that were optimized for nan caller engine. The halfway use remained acknowledgment to nan sixth cogwheel that dropped motor speed. The consequence was a lighter clutch propulsion and smoother clutch engagement which benefitted nan motorcycle's operability successful postulation arsenic well.

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By nan early 2000s, Harley riders were walking farther and faster than ever before. The move to a six-speed gearbox was nan company's effort to refine nan riding acquisition without watering down its character. The Cruise Drive transmission brought genuine engineering improvements to backmost that up. It featured caller gears, bearings, and soul lipid passages, on pinch canine rings alternatively of moving gears. The usage of canine rings allowed quicker, much precise cogwheel changes pinch little lever throw. 

On nan Touring and Dyna models, nan transmission's caller sealed lipid passages eliminated outer lipid lines, reducing leaks and simplifying maintenance, while Softail models retained their classical outer routing. To make it easier connected nan riders, Harley added a ball-and-ramp clutch system that reduced lever effort and made stop-and-go postulation acold little punishing.

As nan creation evolved, Harley engineers continued pinch subtle improvements. A redesigned displacement drum pinch optimized neutral-pocket geometry made it easier to find neutral successful nan Milwaukee-Eight VVT 121 engine-powered Harley's Custom Vehicle Operations (CVO) models. And while nan overdrive sixth cogwheel already reduced motor velocity astatine road pace, Harley tuned later versions of nan Cruise Drive to tally moreover smoother astatine sustained speeds. Lower rpms not only meant amended substance system and little noise, but besides reduced the vibrations Harleys are infamous for and improved long-distance comfort.

Still, nan Cruise Drive hasn't been wholly trouble-free. Early accumulation runs suffered from cogwheel whine, base wear, and nan occasional neutral-finding rumor – quirks acquainted to anyone who's spent clip successful Harley's mechanical lineage. But those teething issues aside, nan six-speed gearbox cemented H-D's move into nan modern era, becoming nan caller standard.