3/19/2023 0 Comments 63 thunderbird![]() ![]() For instance, the lock washers used on the flywheel retaining bolts were eliminated in favor of a dab of Loctite. Countless improvements were made in them, however. So, the cases were entirely new, however the basic architecture, and (although in modified or improved form, perhaps) the core components remained fundamentally the same. Of course the entire mess was now contained within a single compact assembly, which was a major leap forward over the gaggle of separate components that came before. The Reynolds 3/8 X 5/8 final drive chain was 104 links in length.ġ963 TRIUMPH THUNDERBIRD ENGINE IMPROVEMENTS Tension was now adjusted via a neoprene-lined rubber slipper at the bottom of the primary case, a huge improvement over the old, pre-unit method. The engine sprocket was 29 teeth, running a Reynolds 3/3 X 0.225 duplex endless chain with 84 links. The 58-tooth duplex sprocketed cast-iron clutch basket housed 6 plain steel drive plates and 6 steel driven plates faced with Neo-Langite cork, compressed by 3 springs. The clutch now had a 3-paddle rubber shock absorber. The clutch actuator mechanism was now housed inside the outer gearbox cover on the right side, which now operated a pushrod that ran through the center of the mainshaft from one side to the other, to the clutch, on the left side. The different primary drive ratio required a 20-tooth final-drive sprocket. Only the speedo drive gears were changed, to 10 and 15 teeth. While the new unit-construction cases now housed the gearbox, internally the gearbox was virtually unchanged from before. A new frame, suspension and brakes were huge improvements over the non-unit bikes.ġ963 TRIUMPH THUNDERBIRD GEARBOX IS DIFFERENT… Needless to say, the new unit construction machines were simpler (which also made them cheaper and easier to produce), lighter, more compact and more powerful. To compound matters, the primary chain tension was adjusted by sliding the gearbox fore-and-aft in its mounts (another opportunity for play), which then affected the tension of the final drive chain, which was also attached to the gearbox. It seems obvious now, but up to that time, the state of the art was to mount engine, primary and gearbox as separate units within a complex set of heavy brackets that were prone to flex, loosen and get sloppy. But what a change! Unit Construction incorporated the engine, the primary drive, and the gearbox into one neat package. It was a major transition, with nearly every component replaced. 1963 TRIUMPH THUNDERBIRD GOES UNIT CONSTRUCTIONĪlong with the rest of the Triumph 650 line, the 1963 6T Thunderbird converted over to Triumph’s incredible new unit-construction powerplant, frame and cycle gear. ![]()
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