1956 Triumph Speed Twin

1956 TRIUMPH SPEED TWIN RELEGATED TO THE BACK SEAT
The 1938 Triumph Speed Twin was the first vertical twin to hit the market, just prior to WWII, and it changed everything. Almost the entire British motorcycle industry rushed to copy their success as soon as the war ended. At that moment in time, the 5T Speed Twin was at the top of not only Triumph's model lineup, but among motorcycles of the day, in general. But Triumph continued to lead the way, with hotter and more powerful versions, starting in 1946 with the T100 Tiger, which as essentially a 5T Speed Twin with higher compression and hotter cams. Suddenly, the Speed Twin was no longer top dog, the Tiger was getting all the attention. In 1950, Triumph bored and stroked the 500 creating the first Triumph 650 twin, the 6T Thunderbird, moving the 500 Speed Twin farther down the ladder. In 1953, Triumph applied "the Tiger treatment" (ie: higher compression and hotter cams) to the 650 and created the 650 Tiger 110. This was followed in 1956 by the 650 TR6, now sporting the aluminum "Delta head", which was followed up in 1959 by the twin-carb 650 Bonneville. All the while, the lowly 5T Speed Twin was relegated to Triumph's entry-level heavy twin. They had a 350 twin version also, but those were considered middleweights. That meant that the Speed Twin, which at one time was one of the world's premium motorcycles, had fallen all the way to bread-and-butter commuter. It went unit-construction in 1959, gaining the now-famous "Bathtub" styling, and ran through 1966.

1956 TRIUMPH SPEED TWIN-CONTINUAL IMPROVEMENTS
Triumph implemented a series of improvements on all their twins for 1956. The Speed Twin being at the bottom of the food chain wasn't a recipient of Triumph's new alloy Delta head, that was reserved for the hot rod Tiger and the hotter still, new-for-1956 650 TR6. But the lowly Speed Twin still benefited by numerous improvements. Internally, the old white metal big end rod bearings were replaced with shell-type Vandervell babbit metal steel-backed thin wall bearings. New connecting rods with larger big-end eyes were needed, which were larger and therefore threw off the crankshaft balance, requiring modifications to the counterbalances. In the interest of added strength, Triumph started using the 6T 650's cylinder block (with smaller bores), which also required the 650s crankcases, to fit the larger spigot. So, from 1956 on, any 500 twin can be enlarged to a 650, as all parts were now interchangeable between the 500 and 650 twins.


1956 Triumph 5T Speed Twin SPECIFICATIONS

Model Designation

Engine numbers

Production dates

Engine type

Displacement

Bore & Stroke

Compression ratio

Carburetor

Engine output

Top Speed

Electrical system

Primary drive

Clutch

Gearbox

Final drive

Frame construction

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Wheel, front

Wheel, rear

Wheelbase

Seat height

Ground clearance

Weight

Triumph 5T Speed Twin

71642 to 82443, then 0602 to 0932

Sept 15, 1955 to Aug 22, 1956

Air-cooled OHV vertical twin

498cc

63mm X 80mm

7.0:1

one- Amal Monobloc, 1-5/16"

28 bhp @ 6,000 rpm

85-90 mph

6-volt, Lucas magdyno

Chain, 1/2" X 0.305" X 70 links

Multi-plate, wet

4-speed constant mesh, right-foot shift

Chain, 5/8" X 3/8" X 100 links

Steel tube, brazed lug

Telescopic

Swing arm, 2 dampers

7-inch SLS drum

7-inch SLS drum

3.25" X 19.0"

3.50" X 19.0"

56.0"

31.0"

5.0"

395 lbs, dry


MORE SPEED TWIN PAGES:
.....1938
.....1946
.....1947
.....1948
.....1956
MORE TRIUMPH:
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


TRIUMPH THUNDERBIRD SUPER PROFILE


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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