1948 Triumph Speed Twin

1948 TRIUMPH SPEED TWIN BACKGROUND
In a few short years, the 5T Speed Twin went from being one of the world’s premium performance motorcycles to be Triumph’s entry-level twin. It had been surpassed by the T100 Tiger with its higher compression and hotter cams. And soon it would be bumped down still further when the 650cc 6T Thunderbird came out in 1950. And of course, the rest of the British motorcycle industry were also pushing out bigger and faster machines each year, so the competition was growing fierce. But for now, the 1948 Triumph Speed Twin was a solid seller, and while not the fastest thing on the road, its performance was adequate for the day.

1948 TRIUMPH SPEED TWIN DESIGN
The 500cc twin retained its cast iron cylinder block and head, and was fed by a single Amal carburetor. It was of non-unit construction, with the timing gear on the right, and the primary chain and clutch on the left, as usual. The 4-speed gearbox shifted with the right foot. Triumph continued to use it’s tried-and-true rigid frame, but offered a sprung rear hub as an option. The sprung hub used radially-positioned springs inside it to cushion the bumps. It was fine in theory, but tended to move in unintended ways when worn out or under extreme loads (ie: hard acceleration). It was a poor compromise solution, but one that made sense to Triumph at the time. It was a way to get some rear suspension while retaining their rigid frame, a very expensive thing to replace. The front end now had Triumph’s own telescopic forks with hydraulic damping.


1948 Triumph Speed Twin SPECIFICATIONS

Model Designation

Engine Number prefix

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

Fuel capacity

Weight

Triumph 5T Speed Twin

47-5T

Air-cooled OHV vertical twin

498cc

63mm X 80mm

7.0:1

one- Amal 15/16"

28 bhp @ 6,000 rpm

85-90 mph

6-volt, Lucas magdyno, 40watt

Chain

Multi-plate, wet

4-speed constant mesh, right-foot shift

Chain

Steel tube, brazed lug

Telescopic

Rigid frame, sprung hub

7-inch SLS drum

7-inch SLS drum

3.25" X 19.0" Dunlop Universal

3.50" X 19.0" Dunlop Universal

54.0"

29.5"

6.0"

4 Imp gal

361 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




Vintage Motorcycle Calendar - Classic Motorcycle Calendar - Calendars 2018 - 2019 Wall Calendars - Motorcycle Calendar - Classic British Motorbikes 16 Month Wall Calendar by Avonside


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





Travelling With Mr Turner





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 - 1948 Triumph Speed Twin
Last updated 10/14/18

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

HAPPY
HOLIDAYS



BREAKING NEWS:

BSA to Lauch in India First 



NEW PAGE:
Vintage Motorcycle Pictures



2019
 CALENDARS ARE HERE!



Visit our new
Motorcycle Store

WHITWORTH WRENCH & SOCKET SET



Please visit our
MOTORCYCLE BOOK STORE


Subscribe to your favorite
MOTORCYCLE MAGAZINES



BIKES FOR SALE!
Check out our
FREE
Classifed Ads



NEW SECTIONS:

Motorcycle Racing


THIS MONTH'S FEATURE PAGE:
Norton Commando Production Racer

NEW PAGES
added this month:

Norton Commando SS
1977 Triumph Sliver Jubilee
* 1979 Triumph T140D Bonneville Special
* Motorcycle Racing
* 1964 Matchless G3C
* 1955 BSA Gold Star
* AJS Motorcycles
* Helmet Features 2018
* AJS Motorcycles
* 1961 AJS Model 31
* 1959 AJS Model 16
* 1927 AJS Model H4
* 1959 AJS Model 31 CSR
* 1946 AJS Model 18
* 1964 AJS Model 16
* Norton Commando Hi-Rider
* 1953 AJS Model 18
* 1950 AJS 7R Boy Racer
Enjoy. More coming soon...