1968 Triumph Bonneville

OVERVIEW
The 1968 Triumph Bonneville had a bit of a watershed year. While the slow march of progress continued, 2 major improvement were made: Amal Concentric carburetors replaced the Amal Monoblocs; and a new 8" TLS (Twin Leading Shoe) front brake replaced the age-old SLS (single leading shoe) unit. But 1968 also marked the beginning of a very brief window when the Triumph Bonneville was in it's 'sweet spot', widely considered to run from 1968 through 1970. The 'Bonnie' had truly reached its zenith, and at a time when its performance was considered world-class. This was, of course, just before the arrival of the game-changing Honda 750, the bike that reset the world's opinion of what "performance" was. And in this new 4-cylinder OHC paradigm, the ancient pushrod twin just couldn't keep up. Model designations were as before, T120R was the road version & T120C was the off-road/street scrambler (ala enduro). Absent, however, was the race-ready TT Special, the model was dropped entirely for the 1968 model year.
1968 TRIUMPH BONNEVILLE ENGINE UPGRADES
Big changes were made to the engine. Hepolite pistons were back, but with reinforced crowns. Grey Spot outer valve springs replaced last years Red Spots, allowing higher valve lift. Starting with Engine #DU79965, the rocker arms were strengthened by eliminating the oil passages that ran from their pivots to the contact faces. The cylinder block got 12-point base nuts. Starting with Engine #DU66246, the threaded timing hole (used to locate TDC) that was behind the cylinders was moved to a location below the front engine mount. The flywheel now had 2 notches, one at TDC and one at 38-degrees BTDC (the standard advance at the time). But to make it more convenient to time the engine, an entirely new system was employed as of Engine #DU83021, which included a new primary cover with removable inspection plate over the alternator stator and corresponding timing marks on the stator & the primary cover. Ultimately, the threaded inspection hole in front was turned into a drain plug & the timing plug moved back to its original location, behind the cylinder block. The contact breakers were now independently adjustable (Lucas 6CA) allowing more precise timing. More Unified threads inside and out. Several detail changes were made to the transmission. The Zener diode was moved from behind the engine to the front of the bike under the front yoke, where it would remain from then on.
1968 TRIUMPH BONNEVILLE FRAME & RUNNING GEAR
An overall strengthening of the frame was undertaken, starting somewhere between Engine #s DU75430 & DU75449 (a 19-bike disparity), thicker-gauge tubing was used for the front frame section, and as of Engine #DU81196 for a stronger swing arm. The swing arm pivot lug was also strengthened. A new set of forks were fitted that looked practically identical to the units they replaced, but had internal differences such as 2-way shuttle valve damping & changed over to American threads.
1968 TRIUMPH BONNEVILLE GETS NEW TLS FRONT BRAKE
The big news for 1968 however was the new 8" twin-leading-shoe (TLS) front brake to replace the old SLS unit. A modified version of the old hub was used with an entirely new guts & an alloy backing plate that had the coolest-looking air scoop in the front. It was 'all business' in more than appearance - it really stopped!

---

1968 Triumph Bonneville
SPECIFICATIONS

---

MORE TRIUMPH BONNEVILLES:
Triumph Bonneville
Triumph Bonneville Pre-Unit (1959-1962)
.....1959
.....1960
.....1961
.....1962
Triumph Bonneville, Unit-Construction(1963-1970)
.....1963
.....1964
.....1965
.....1966
.....1967
.....1968
.....1969
.....1970
Triumph Bonneville, Oil-in-Frame
.....1971
.....1972
.....1973
.....1974
.....1975
.....1976
.....1977
.....1978
.....1979
.....1980
.....1981
.....1982
.....1983
Les Harris Bonnevilles(1983-1989)
OTHER TRIUMPHS:
Triumph TR6
Triumph TR7
Triumph Trophy
Triumph Tiger
Triumph Thunderbird
Triumph Trident
Triumph X-75 Hurricane

---

Check out these TRIUMPH BOOKS

---

2018 Classic Triumph Calendar

---

Triumph Motorcycles: The art of the motorcycle

---

The Complete Book of Classic and Modern Triumph Motorcycles 1937-Today (Complete Book Series)

---

Triumph Motorcycles: From Speed-Twin to Bonneville

---

Triumph Bonneville and TR6 Motorcycle Restoration Guide: 1956-83

---

British Motorcycles Triumph (Little Books)

---

Triumph Motorcycles in America

---

McQueen's Motorcycles: Racing and Riding with the King of Cool

---

Triumph Motorcycle Restoration

---

Illustrated Triumph Motorcycles Buyer's Guide: From 1945 Through the Latest Models (Illustrated Buyer's Guide)

---

Tales of Triumph Motorcycles and the Meriden Factory

---

Hinckley Triumphs: The First Generation (Crowood Motoclassic)

---

For more like these, visit our
TRIUMPH BOOK STORE

---

---

PLEASE BUY MY NEW E-BOOK HERE 12 Chapters & over 100 original photos. My best work yet. ONLY $4.99! Thank you, Andy Tallone, your humble author Click here to buy now: The Random History of Classic British Motorcycles, Volume 1

---

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
.....3T 350 Twins
BSA Motorcycles
.....A65
.....A10
.....A7
.....Gold Star
.....Bantam
.....Rocket 3
.....B50
Norton Motorcycles
.....Commando
.....Atlas
.....Dominator
.....Model 7
.....Manx
.....Navigator
AMC-Associated Motor Cycles
Matchless-AJS Motorcycles
.....G3
.....G9
.....G12
.....G80
Royal Enfield Motorcycles
.....Interceptor
.....Bullet
Ariel Motorcycles
.....Square Four
.....Red Hunter
.....Cyclone
Vincent Motorcycles
.....Black Shadow
.....Rapide
.....Comet
.....Egli-Vincent
Velocette Motorcycles
.....KSS
.....KTT
.....LE
.....MAC
.....Thruxton
.....Venom
.....LE
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
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 STORES
.....Motorcycle Books
.....Motorcycle Magazines
.....Motorcycle Calendars
.....Motorcycle Accessories
..........Motorcycle Helmets
..........Motorcycle Rain Suits
..........Motorcycle Locks & Security
..........Motorcycle T-Shirts
..........Motorcycle Diecast Models
..........GoPro Cameras
.....Motorcycle Parts
..........Motorcycle Tires
..........Motorcycle Chains
..........Motorcycle Batteries
..........Motorcycle Handlebars
.....Motorcycle Tools
..........Whitworth Tools
..........Tire Tools
..........Chain Tools

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

---

Back to top - 1968 Triumph Bonneville
Last updated 12/2/17

---

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