Unit-Construction Triumph TR6
UNIT CONSTRUCTION TRIUMPH TR6 ARRIVES
The Triumph TR6 was introduced in 1956 & as such, like all Triumph twins at the time, it was of Non-Unit (or Pre-Unit) Construction. This meant that the engine package was made up of a separate crankcase, gearbox & primary chaincase, all bolted together with steel plates, in the frame. It was bulky, heavy, prone to flex & expensive to produce & assemble.
OUT WITH THE OLD, IN WITH THE NEW...
Unit Construction refers to the design practice of taking the separate crankcase, gearbox & primary case, then incorporating them into a single set of unitized cases. It was lighter, more compact, stronger (& therefore allowed more power), smoother, cleaner & cheaper to produce & assemble. The Triumph 3TA 350cc twins converted to unit construction in 1957, with the TR5/5TA 500cc twins following in 1959. The big 650 twins were enjoying such success in the late 1950s that Triumph Motorcycles decided to leave well enough alone. So, unit construction wasn't introduced in the Triumph TR6 until the 1963 model year. And it was to remain basically unchanged until the demise of Triumph Motorcycles in the early 1980s.
Unit-Construction Triumph TR6
1963 Triumph TR6
First year for Unit Construction plus an all-new frame & running gear. New 9-bolt head. Spark & lights now via alternator, points & coils. TR6S/S is the only TR6 model.
1964 Triumph TR6
Mostly minor changes to correct & perfect design & production flaws in the new engine, frame & running gear. Seal on kickstart shaft, an all-new front fork assembly with external springs, new gauges & a bigger 1-1/8" Amal carb.
1965 Triumph TR6
Some subtle changes for 1965, further developing the unit construction design. New main bearings, some gearbox upgrades & some general improvements to the frame & running gear. Triumph Motorcycles are at their peak during this era.
1966 Triumph TR6
Good news/bad news: We finally get 12-volt electrics, but it comes with a Zener Diode. Oh well. Steering angle steepened for quicker handling. Slim new tank & that famous "Eyebrow" tank emblem.
1967 Triumph TR6
The big news for 1967 is the switch from the age old Amal Monobloc carburetor to the new Amal Concentric. The parcel rack on top of the tank on US models is eliminated. Otherwise, mostly minor changes.
1968 Triumph TR6
The big news for 1968 was the introduction of a new 8-inch TLS (Twin Leading Shoe) front brake to replace the age-old SLS unit. The TR6 got hotter E3134 cams (like the Bonneville). Zener Diode got moved to the front of the bike.
1969 Triumph TR6
The "Tiger" name appears for the first time on a TR6. Gone is the old "Trophy". Gone also are the old British Standard threads (CEI), in favor of Unified or 'American' threads (UNC & UNF). Numerous engine mods aimed at oil tightness & a new tank badge, the "bird wing".
1970 Triumph TR6
The last year before the switch to the dreaded oil-bearing frame. The timed engine breather is ditched in favor of breathing through the primary case, with a hose running out the back fender. Gone is the rear chain oiler.
1971 Triumph TR6
First year for the Oil-in-Frame Triumph TR6. New oil-bearing frame, new forks, new wheels with cool conical hubs, new pipes, new look. Should have been a hit. Small problem - the engine didn't fit in the new frame. Got production off to a late start. The new TR6 never sold as well as the TR6 it replaced.
1972 Triumph TR6
The new oil-bearing frame is too tall, so seat height is lowered a full 2 inches. A 5-speed gearbox becomes available on the TR6RV models (the "V" signifying a 5-speed). Clamp & spigot exhaust fixing is ditched in favor of pipes that simply slip into the head. Bad idea.
1973 Triumph TR7
A big year for Triumph. 650 grows to 750, new TR7 name, 5-speed gearbox is now standard across the line & finally a front disk brake. Many other smaller changes including a new headlight mounting system.
Visit our Triumph TR7
page for more.
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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 RACING MOTORCYCLES IN AMERICA
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, 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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