The brush-banger type rider will also appreciate the new travel-stop at the bottom of the fork. Time will tell we certainly never noticed any oil escaping during the time we had the Thunderbird, and we rode it well over 1000 miles under all conditions. The people at Triumph swear that this new seal is absolutely effective, and that no oil loss is possible under any conditions. This seal is of the doublelip type, with a spring-backed lower lip to keep the oil in, and an upper lip that serves as a scraper to keep dust and moisture away from the lower lip - which increases its effective life. Those who prefer pounding out through the rough will be pleased to know that there is a new, and more effective, oil seal on the forks. The machine feels so secure when cornering hard that one leans deeper and deeper into the turn - and then curses the stand for hanging down where it can drag. Also, the new forks have considerably better damping than earlier Triumphs, and not only has this improved the ride, but it has done wonders for the handling as well. The new forks have much shorter springs, with larger diameter coils, located outside the upper fork legs above the "sliders." In this position, they do not "scuff" along the fork leg as much as the earlier internal springs, and the ride is thus improved. Previous Triumph forks had long, small-diameter coil springs located inside the fork tubes, and damping was handled by oil squishing past a metering rod. This 12-volt system does not really do anything appreciably better than a 6-volt system, but it will do it a lot longer, and that certainly justifies the change.Īnother change in the Thunderbird (and the other Triumph twins) for 1964 is a completely new set of forks. Voltage regulation is handled by a zener diode transistor mounted in an aluminum plate (for heat dissipation). Current is supplied by an alternator, as on the other Triumphs, but after passing across a silicon crystal full-wave rectifier, it is fed into a pair of 6-volt batteries, connected in series to give 12-volts for the ignition and lighting systems. One very important feature of the Thunderbird, not shared by other Triumphs, is the new 12-volt electrical system. These pistons are, incidentally, slotted so they will not "outgrow" the bore if the engine is overheated. The pistons themselves are being fitted with a bit less clearance than before to give more quiet running. Also in the interest of oil conservation, the Thunderbird has new slotted oil control rings, which should be more effective in scraping from the bores oil thrown up from the connecting rod journals. With this arrangement, any oil that might find its way out of the breather is captured in the supply tank, instead of being lost. In the same general area, the breather has been reworked to improve crank case ventilating, and the hose from the breather has been re-routed up to the oil supply tank, where it leads into the de-frothing tower. For instance, there is the redesigned oil scavenging system, which has a larger sump area to improve scavenging and thus reduce oil drag on the flywheel at high engine speeds. Most people are at least somewhat aware of the overall changes in the Tri umph, but there have been detail changes for 1964 that may have been overlooked. In the 1964 version, the Thunderbird incorporates all of the improvements bestowed on the other big Triumph twins, such as the unit-constructed engine and single down-tube frame of recent years. As a matter of fact, the many improvements introduced over the years have made it even better than before - and that is saying a great deal. Times have changed (the "40-inch 'Bird" was introduced 14 years ago) and there are now faster Triumphs, but the Thunderbird is still an important part of the Triumph line, and it is still a remarkable package of performance and reliability. To them, Thunderbird meant only one thing: Triumph's very smooth and rapid 40 cubic inch vertical-twin motorcycle, which was quite justly regarded as being the machine for the sporting rider. LONG BEFORE a certain automobile manufacturer in Dearborn cribbed the name, "Thunderbird" meant total performance to thousands of motorcycle enthusiasts.
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