1951 Triumph Thunderbird

The 1951 Triumph Thunderbird carried one model designation: "6T", and was known as the 6T Thunderbird, 6T or simply T-Bird. All 1951 Triumph Thunderbird 6T's were 650's & came equipped essentially the same, with the same rigid frame & sprung rear hub, and the same setup throughout. Unlike the later Triumph TR6 which came in a variety of flavors (ie: high pipes, low pipes, competition, etc.).

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

1951 TRIUMPH THUNDERBIRD - OVERVIEW
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 & ineffective. It didn't absorb bumps very well & looseness would develop in the hub leading to uncontrolled wheel movements & erratic handling as the result.

1951 TRIUMPH THUNDERBIRD - COLOR SCHEMES
On a more positive note, the color scheme improved for the 1951 Triumph Thunderbird. Called Polychromatic Blue, it's a handsome metallic blue (pictured here). The Triumph T-Bird had its own logo, the so-called "Paper Dart" (unofficial nickname), pictured on the headlight nacelle above. This would later be cast into the primary cover.
The 1951 Triumph Thunderbird was a handsome machine in its day. The headlight nacelle of the 1951 Triumph Thunderbird 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 & also make them easy to clean, once ridden. The full fenders on this 1951 Triumph Thunderbird are also in keeping with that school of thought. It wasn't until the American Triumph dealers made a fuss that Triumph Motorcycles began to get lean & mean, starting with the 1956 Triumph TR6.


1951 Triumph 6T Thunderbird
SPECIFICATIONS

Engine type

Displacement

Bore & Stroke

Compression

Carburetor

Ignition

Engine output

Primary drive

Primary sprockets

Clutch

Gearbox

Ratios, overall:

1st, bottom

2nd

3rd

4th, top

Final drive

Final drive sprockets

Frame Type

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Tire, front

Tire, rear

Wheelbase

Seat Height

Ground Clearance

Fuel capacity

Dry weight

Air-cooled OHV vertical twin, non-unit

649cc / 40.0 ci

71mm X 82mm / 2.79" X 3.23"

8.5:1 (US & export); 7.0:1 (UK)

1- Amal Monobloc, 1-1/16"

Lucas magneto

34 bhp @ 6500 rpm

1/2" X .335" X 5/16" chain, 70 links

24T X 43T

Multi-plate, wet

4-speed constant mesh, right foot shift


11.9:1

8.25:1

5.81:1

4.88

5/8" X .400" X 3/8" chain, 101 links

18T X 46T

Brazed lug, rigid

Telescopic fork, hydraulic damping

Sprung rear hub, rigid frame

7" SLS drum

7" SLS drum

3.25" X 19"

3.50" X 19"

55.25" / 140.3 cm

31" / 77.5 cm

5" / 12.7 cm

3 Imp gal (US); 4 Imp gal (UK & export)

370 lbs / 168 kg


MORE THUNDERBIRD PAGES:
Triumph 6T Thunderbird
.....Pre-Unit Thunderbird
.....1950
.....1951
.....1952
.....1953
.....1954
.....1955
.....1956
.....1957
.....1958
.....1959
.....1960
.....Unit-Construction Triumph Thunderbird
.....1963
MORE TRIUMPHS:
Triumph T120 & T140 Bonneville
Triumph TR6
Triumph TR7
Triumph T110 & T110 Tiger
Triumph 6T Thunderbird
Triumph 5T Speed Twin
Triumph T150 & T160 Trident
Triumph X-75 Hurricane


Check out these TRIUMPH BOOKS

COMPLETE BOOK OF CLASSIC & MODERN TRIUMPHS


TRIUMPH MOTORCYCLES IN AMERICA


TRIUMPH MOTORCYCLE RESTORATION


TRIUMPH MOTORCYCLE RESTORATION, PRE-UNIT


TRIUMPH BONNEVILLE & TR6 RESTORATION GUIDE: 1956-1983


TALES OF TRIUMPH MOTORCYCLES & THE MERIDEN FACTORY


TRIUMPH 650 & 750 TWINS OWNERS WORKSHOP MANUAL, 1963-1983


TRIUMPH BONNEVILLE: ESSENTIAL BUYER’S GUIDE


TRIUMPH BONNEVILLE: PORTRAIT OF A LEGEND


ILLUSTRATED TRIUMPH BUYER’S GUIDE, by Roy Bacon


TRIUMPH BONNEVILLE, 2001-2015


TRIUMPH: PRODUCTION TESTERS TALES FROM MERIDEN


TRIUMPH MOTORCYCLE RESTORATION GUIDE


TRIUMPH OWNERS HANDBOOK, UNIT-CONSTRUCTION 350 & 500, Kindle


TRIUMPH ILLUSTRATED WORKSHOP MANUAL 1945-1955, by Clymer


TRIUMPH TWINS & TRIPLES


FACTORY-ORIGINAL TRIUMPH TWINS, 1938-1962


TRIUMPH BONNEVILLE & TR6, by Timothy Remus


TRIUMPH MOTORCYCLES: FROM SPEED TWIN TO BONNEVILLE


TRIUMPH MOTORCYCLES: THEIR RENAISSANCE & THE HINKLEY FACTORY


TRIUMPH PRE-UNIT TWINS OWNERS WORKSHOP MANUAL


TRIUMPH THRUXTON BONNEVILLE 1959-1969


TRIUMPH MOTORCYCLES ILLUSTRATED WORKSHOP MANUAL 1937-1951, by Clymer


TURNER’S TRIUMPHS: EDWARD TURNER & HIS TRIUMPHS


TRIUMPH TWIN RESTORATION, by Roy Bacon


TRIUMPH TIGER CUB & TERRIER 1952-1968, Haynes Repair Manual


TRIUMPH 675 DAYTONA & SPEED TRIPLE REPAIR MANUAL 2006-2010, Haynes


CLASSIC MOTORCYCLES: TRIUMPH


TRIUMPH BONNEVILLE YEAR BY YEAR


TRIUMPH TRIPLES


TRIUMPH RACING MOTORCYCLES IN AMERICA


TRIUMPH MOTORCYCLES


TRIUMPH, by Roy Bacon


TRIUMPH 750/900 TRIPLES & 1200 FOURS 1991-1999, Haynes Repair Manual


TRIUMPH TROPHY BIBLE


TRIUMPH DAYTONA, SPEED TRIPLE SPRINT & TIGER: 885/955 1997-2005, Haynes Repair Manual


BSA & TRIUMPH TRIPLES GOLD PORTFOLIO 1968-1976


TRIUMPH TRIDENT OWNERS WORKSHOP MANUAL, by Haynes


TRIUMPH: A CENTURY OF PASSION & POWER


TRIUMPH BONNEVILLE, by Osprey


TRIUMPH TIGER 100 & 110, 1939-1961, by Roy Bacon


TRIUMPH TIGER 100 & DAYTONA


TRIUMPH BONNEVILLE, by Crowood


TRIUMPH by Don Morley


TRIUMPH TRIPLES & FOURS 1991 & 2004


TRIUMPH 350 & 500 1957-1974 ESSENTIAL BUYERS GUIDE


BONNIE: THE DEVELOPMENT OF THE TRIUMPH BONNEVILLE


TRIUMPH SINGLES: EARLY DAYS TO 1974, by Roy Bacon


TRIUMPH: RETURN OF THE LEGEND


TRIUMPH FUEL INJECTED TRIPLES 1997-2000


BOOK OF TRIUMPH TWINS 1968-1969, by Floyd Clymer


THE TRIUMPH STORY: RACING & PRODUCTION MODELS 1902-PRESENT


TRIUMPH 350 & 500 TWINS 1958-1973, Haynes Repair Manual


TRIUMPH BONNEVILLE 2001-=2008 ROAD TEST PORTFOLIO


HINKLEY TRIPLES & FOURS


TRIUMPH PRE-UNIT TWINS


HINKLEY TRIUMPHS: THE FIRST GENERATION


TRIUMPH BONNEVILLE BIBLE: ALL MODELS 1959-1983


TRIUMPH TWENTY-ONE TO DAYTONA: C CLASS 350 & 500 TWINS


ORIGINAL TRIUMPH BONNEVILLE


TRIUMPH 650 & 750 TWINS


TRIUMPH MOTORCYCLES & CUSTOM BIKES


TRIUMPH MOTORCYCLES


TRIUMPH, THE LEGENDS SERIES


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TRIUMPH SPEED TWIN & THUNDERBIRD BIBLE


TRIUMPH BONNEVILLE T120/T140


TRIUMPH MOTORCYCLES FROM 1950-1983


TRIUMPH & BSA TRIPLES: THE COMPLETE STORY


TRIUMPH THUNDERBIRD, TROPHY & TIGER ESSENTIAL BUYERS GUIDE


TRIUMPH TIGER CUB BIBLE


ROAD RACING HISTORY OF THE TRIUMPH 500 UNIT TWIN


EDWARD TURNER: THE MAN BEHIND THE MOTORCYCLES


SAVE THE BONNEVILLE: THE INSIDE STORY OF THE MERIDEN WORKERS CO-OP


TRIUMPH DAYTONA 1991-2006 ROAD TEST PORTFOLIO


TRIUMPH DAYTONA 2003-2009 ROAD TEST PORTFOLIO


TRIUMPH TIGER 100 / DAYTONA: DEVELOPMENT HISTORY


TRIUMPH, by Daniel Gilpin


BOOK OF TRIUMPH MOTORCYCLES ILLUSTRATED SHOP MANUAL 1935-1939


TRIUMPH: THE RACING STORY


TRIUMPH BONNEVILLE T120 1959-1974, by Roy Bacon


TRIUMPH BONNEVILLE GOLD PORTFOLIO 1959-1983


TRIUMPH TRIDENT SUPER PROFILE


ILLUSTRATED TRIUMPH BUYERS GUIDE, by Roy Bacon






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