1951 Triumph Thunderbird

1951 Triumph Thunderbird Background & History

The 1951 Triumph Thunderbird carried the model designation “6T”.  All 6T Thunderbirds were 650 twins which in itself was a bored-and-stroked 500 twin.  But, the Thunderbird shared more than just engine design with it’s little brother, the 500 cc Speed Twin.  They also shared their rigid frame, front forks, sprung rear hub, brakes and wheels, and bodywork. Visually, only the paint colors differed between the two models.  The 1951 Triumph Thunderbird was painted polychromatic blue.

1951 Triumph Thunderbird had a Little Brother

When the 500cc Speed Twin launched in 1938 it was Triumph’s first twin and thus was their hottest bike.  But it only took one model year for Triumph to hot rod their hottest bike to create one even hotter.  The 1939 T100 Tiger had higher compression, a bigger carburetor and hotter cams, making it Triumph’s hot rod, and relegating the Speed Twin to more basic transportation.  The same thing happened to the T-bird.  When it launched in 1950, the 650cc Thunderbird was the hottest thing on the market.  But just 4 years later, it too was passed up by the hot rod version, the T110 Tiger.  This left the Thunderbird as their basic transport bike in the 650-class.  The Speed Twin and the Thunderbird would continue throughout their lives as the entry-level bikes in their respective size classes, and thus Triumph’s entry-level twins.

1951 Triumph Thunderbird is Carried Over

The 1951 Triumph Thunderbird carried over largely unchanged from its 1950 model year introduction. There were the usual incremental improvements to engine and gearbox, mostly designed to improve reliability, ease vibration or simplify assembly. But Triumph and their ace designer Edward Turner, knew they had a hit on their hands and left things well enough alone with the 1951 Triumph Thunderbird. After all, don’t fix it if it ain’t broke.

1951 Triumph Thunderbird Features

On the 1951 Triumph Thunderbird, the Amal carburetor was increased in size from 1 inch to 1-1/16 inch. The 7-inch SLS front brake was also improved. The same brazed-lug rigid frame soldiered on with the notorious sprung rear hub trying to pass as rear suspension. It was an atrocious compromise implemented (indeed invented) by none other than Edward Turner himself as a way to delay the expensive retooling needed to adopt a more contemporary swing arm rear suspension. It was crude and fairly ineffective. It didn’t absorb bumps very well and looseness or ‘play’ would develop in the hub leading to uncontrolled wheel movements and erratic handling as the result.

1951 Triumph Thunderbird Styling

On a more positive note, the color scheme improved for the 1951 model year. Called Polychromatic Blue, it’s a handsome metallic blue (pictured here). The 1951 Triumph Thunderbird had its own logo, the so-called “Paper Dart” (unofficial nickname), which was a decal on the headlight nacelle. (See the photo below.) This would later be cast into the primary cover.

The 1951 Triumph Thunderbird was a handsome machine in its day. The headlight nacelle incorporated the headlight, gauges (clocks), and handlebar mounts all in one neat package. This was a British innovation, intended to help keep the bikes clean in typically inclement British weather and also make them easy to wipe down and dry off, once ridden. The full fenders on this T-Bird are also in keeping with that school of thought. It wasn’t until the American Triumph dealers made a fuss about the stodgy styling that Triumph began to get lean and mean, starting with the1956 Triumph TR6.  However, even after this tidal change, the Triumph Thunderbird soldiered on as their big-bore commuter bike.  In fact, they went even farther with this (perhaps too far) when the T-bird adopted Triumph's controversial 'bathtub-styling' in the late 50's, which enclosed the entire rear section of the bike, again in the interest of keeping moisture and dirt out for all those rain-soaked British commuters.

1951 Triumph Thunderbird Specifications

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1951 Triumph Thunderbird Books

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More Triumph Thunderbird Pages

1950 Triumph 6T Thunderbird
1951 Triumph 6T Thunderbird
1952 Triumph 6T Thunderbird
1953 Triumph 6T Thunderbird
1954 Triumph 6T Thunderbird
1955 Triumph 6T Thunderbird
1956 Triumph 6T Thunderbird
1957 Triumph 6T Thunderbird
1958 Triumph 6T Thunderbird
1959 Triumph 6T Thunderbird
1960 Triumph 6T Thunderbird
1961 Triumph 6T Thunderbird
1962 Triumph 6T Thunderbird
1963 Triumph 6T Thunderbird
1964 Triumph 6T Thunderbird
1965 Triumph 6T Thunderbird

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