1968 Triumph TR6

1968 TRIUMPH TR6 NOMENCLATURE
For years, every Triumph TR6 was referred to as a Triumph Trophy, but that was soon to change. For the first time, for the 1968 model year, the name "Trophy" was dropped. By the following year, the new name of Triumph Tiger would be adopted. Since the original Triumph T110 Tiger had recently been dropped, it freed up the name for TR6 duty. Models for the 1968 Triumph TR6 line were the Standard TR6, the TR6R Roadster, TR6C Competition & the TR6P for Police duty. Engine & frame numbers ran from DU68364 to DU85903 with build dates running from August 9, 1967 to June 26, 1968.

ENGINE UPGRADES
The exhaust cam was replaced with the more radical E3134 racing cam, making both the intake (inlet) & exhaust cams the same, which it now had in common with the Bonneville. 1-1/8-inch cam followers continued to be specified for both inlet & exhaust. The 'Red Dot' outer valve springs were replaced by 'Green Dot' springs with 10% more load when fully open, but retaining the original loading when closed. Starting with Engine #DU81209 the internal oilways in the rocker arms were deleted, adding strength to cope with the stronger springs. Stronger connecting rods with a greater cross-section & the H&G pistons were redesigned (removing the bar under the crown & thickening the ring groove-area. Left-hand threads were specified for the tachometer (rev counter) drive. To make more room for wrenches (spanners) the cylinder base nuts were changed to 12-points.
TIMING IS EVERYTHING
For the 1968 Triumph TR6, there were 3 different ignition timing regimens indicated on the crankcase & flywheel providing TDC (Top Dead Center) & 38-degrees BTDC (Before Top Dead Center):

MkI - The timing plug was located at the lower front of the crankcase, with only one hole or slot in the flywheel below the crankshaft bobweight. This gave 38 degrees BTDC.

MkII - Two timing plugs were fitted to the crankcase, the first the same as the MkI, the other behind the cylinder block. The flywheel holes were situated one below the bobweight & one above, giving 38-degrees BTDC & TDC.

MkIII - Timing plug was behind the cylinder barrel & the flywheel had two slots above the crankpin, giving 38-degrees BTDC & TDC. MkIII began with Engine #DU74052.

GEARBOX STUFF
Lots of internal changes were made to the gearbox including the mainshaft high gear, oil seals, clutch operating mechanism & the whole thing was converted over to UNF threads. The 1968 Triumph TR6 got a new primary cover with a round removable inspection plate over the rotor to aid ignition timing. And staring with Engine #DU85346 a pointer was added to the crankcase to aid in the process.

FRAME MODS
The anti-theft steering lock was improved. The rear was modified to mount the left side cover, which contained the toolbox. A stronger swingarm was introduced at #DU81209 with 12-gauge instead of 14-gauge tubing & heavier corner gussets (fillets). These strengthened swingarms can be identified by the letter "X" stanped onto their pivot tube. The 1968 Triumph TR6 got a new one-piece forged steel kickstand (prop stand).

BIG NEWS: NEW TLS FRONT BRAKE
The 1968 Triumph TR6 received an all-new 8-inch TLS (Twin Leading Shoe) front brake, arguably the best Triumph Motodycles ever put on a classic Triumph. It worked very well & it looked great.

ELECTRICAL CHANGES
The Zener Diode gained a finned heat sink & was moved from the battery tray to a the front of the bike, under the headstock, where it could get more cooling air. A new 5-1/4" headlight housed a 3-position light switch, a Lucas ammeter & warning lights. Lucas 6CA contact breakers now allowed (required) each side to be independently set. This larger unit forced the condensers to be moved to another location, under the front petrol tank mounting bracket. At #DU82146 lubricating felt wicks were added to the the breakers to combat premature wear. OTHER CHANGES
US models got safety reflectors mounted on either side of the tank under the nose. After #DU81209, the front tank mounting studs were replaced with bolts. From #DU82574, the TR6C's high pipes got an "H"-section connecting the two pipes just upstream of the silencers to try to quiet them, in anticipation of impending noise regulations. The front mudguard (fender) was lengthened slightly on all models except the TR6C. A new seat with external hinges had a gray ribbed top, white piping, black sidewalls & chrome plastic beading around the lower edge. The new seat pan had threads to accommodate a new passenger grab rail (on US models only).

CHANGE TO "UNIFIED" THREADS
After eons of using the old British Standard Cycle (BSC) system for all their nuts, bolts & threads (also known as Cycle Engineers Institute, or CEI), with the 1968 Triumph TR6 & the entire Triumph Motorcycle lineup, the process of changing over all threads to UNF (Unified Fine) & UNC (Unified Course), also known (in America, at least) as "American threads" (no offense to our British mates). Not everything could be changed over at once, so there are quite a mixture of threads & bolt-head sizes on 1968 & 1969 Triumph Motorcycles. An interesting sidenote: even the Americans were leaving 'American threads' in favor of the Metric system. Why did Triumph go through all the trouble & expense of changing all the threads, then convert them to another antiquated system that was on its way out? I guess this was indicative of the thinking at that time. And of course, the US market was, by far, the largest retail market for British Motorcycles. Perhaps they thought they were paying homage to the Yanks by using 'their' threads. Either way, if you're working on a 1968 Triumph TR6, you'd better have two sets of wrenches & sockets, one American & the other Whitworth.

1968 Triumph TR6 SPECIFICATIONS

Model Designations:

TR6

TR6C

TR6R

TR6P

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 sprockets

Frame type

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Tire, front

Tire, rear

Fuel Capacity

Wheelbase

Seat height

Ground clearance

Dry Weight


Standard

Competition/Off-road

Roadster

Police

Air-cooled OHV vertical twin

649cc / 40.0 ci

71mm X 82mm / 2.79" X 3.23"

8.5:1

1- Amal Concentric, 30mm

Battery & coil, Lucas

42 bhp @ 6500 rpm

3/8" triplex chain X 84 links

Engine 29T X Clutch 58T

Multi-plate, wet

4-speed constant-mesh, right-foot shift


11.8:1

8.17:1

6.76:1

5.84:1

5/8" X .400" X 3/8" chain X 106 links

Gearbox 19T X Rear 47T

Brazed lug, full-cradle, single downtube

Telescopic fork, hydraulic damping

Swing arm, 2 Girling dampers

8" SLS drum, full-width

7" SLS drum, one-side

3.25" X 19" Dunlop

4.00" X 18" Dunlop

2.5 Imp gal (US)/4 Imp gal (UK & export)

54.5" / 140.3 cm

32.5" / 77.5 cm

5.0" / 12.7 cm

380 lbs / 173 kg


MORE TRIUMPH TR6 PAGES:
Triumph TR6
Triumph TR6, Pre-Unit (1956-1962)
.....1956
.....1957
.....1958
.....1959
.....1960
.....1961
.....1962
Triumph TR6, Unit-Construction (1963-1970)
.....1963
.....1964
.....1965
.....1966
.....1967
.....1968
.....1969
.....1970
Triumph TR6, Oil-in-Frame (1971-1972)
.....1971
.....1972
Triumph TR7
.....1973
.....1976

OTHER TRIUMPHS:
Triumph Bonneville
Triumph Trophy
Triumph Tiger
Triumph Thunderbird
Triumph 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






Please visit our
MOTORCYCLE BOOK STORE


Take a tour of our site...

HOME PAGE
Triumph Motorcycles
.....Bonneville
.....Tiger
.....Trophy
.....TR6
.....TR7
.....Trident
.....X-75 Hurricane
.....6T Thunderbird
.....5T Speed Twin
.....Daytona
.....Twenty-One
BSA Motorcycles
.....A65
.....A10
.....A7
.....Gold Star
.....Bantam
.....Rocket 3
Norton Motorcycles
.....Commando
.....Atlas
.....Dominator
.....Manx
Matchless-AJS Motorcycles
.....G3
.....G9
.....G12
.....G80
AMC-Associated Motor Cycles
Royal Enfield Motorcycles
.....Interceptor
.....Bullet
Ariel Motorcycles
.....Square Four
.....Red Hunter
Vincent Motorcycles
.....Black Shadow
.....Comet
Velocette Motorcycles
.....KSS
.....LE
.....MAC
.....Thruxton
Rickman Motorcycles
Japanese Motorcycles
.....Honda
.....Kawasaki
.....Suzuki
.....Yamaha
Cafe Racers
....Triumph Cafe Racers
.....Norton Cafe Racers
.....Other Cafe Racers
Choppers & Bobbers
.....Choppers
.....Triumph Choppers
.....BSA Choppers
.....Rat Bikes
Classic Racing Motorcycles

Classic Motorcycle Events
.....Auctions
.....Shows
.....Rides
Classic Motorcycle Restoration
Classic Motorcycle Shops
Classic Motorcycle Clubs
Classic Motorcycle Photo Gallery
Send us Pictures of YOUR BIKE
YOUR BIKE Pictures

HOME PAGE
.....About Us
.....Site Map
.....CONTACT US
.....Please visit our BLOG
.....Subscribe to our FREE e-zine BRIT IRON
.....BRIT IRON E-zine Back Issues

Visit our STORE
.....Motorcycle Books
.....Motorcycle Magazines
.....Motorcycle Calendars
.....Motorcycle Helmets
.....GoPro Cameras

Crazy about cars, too? Check out our sister site:
www.American-Muscle-Cars.net

Back to top - 1968 Triumph TR6
5/6/16

Learn how to BUILD YOUR OWN WEBSITE, like I did.

2016 CALENDARS


Please visit our
MOTORCYCLE BOOK STORE


Subscribe to your favorite
MOTORCYCLE MAGAZINES





We now sell
GoPro CAMERAS




BIKES FOR SALE!
Check out our
FREE
Classifed Ads


Get your next
MOTORCYCLE HELMET
here


NEW PAGES
added this month:

1934 BSA Blue Star
Triumph T140W TSS
1955 Matchless G9B
1963 Matchless G12CS
Triumph Daytona
1967 Triumph Daytona
1968 Triumph Daytona
1969 Triumph Daytona
1970 Triumph Daytona
1973 Triumph Daytona
2009 Triumph Bonneville Thruxton
Triumph Twenty-One
1959 Triumph Twenty-One
1960 Triumph Twenty-One
1961 Triumph Twenty-One
Norton Navigator
1962 Norton Navigator
1962 Norton Navigator Deluxe
Norton Jubilee
1970 Norton Mercury
1964 Norton Atlas
1962 Norton Dominator 650SS
1969 Norton Dominator 650SS
Enjoy. More coming soon...