1958 Triumph TR6

ABOVE: This 1958 Triumph TR6 Trophy features the optional twin high pipes, very popular in the US Market, which could replace the 2-into-1 side exhaust.

1958 TRIUMPH TR6 BY THE NUMBERS
1958 Engine/Frame Numbers: 011861 to 019244
Production Dates: October 10, 1957 to June 25, 1958

ENGINE CHANGES
Early Delta Heads were prone to cracking around the valve seats. It was deemed prudent to reduce the sizes of the intake (inlet) and exhaust valves to increase the amount of material around the seats. Intakes went from 1-19/32" to 1-1/2", and exhausts dropped from 1-7/16" to 1-11/32". The combustion chamber was reconfigured to suit. While this may have cured the cracking problem, the smaller valves hurt performance. Because of this, the early Delta heads with the bigger valves remained popular with racers. Despite this, however, performance continued to increase until crankshafts began snapping. Until then, the pre-unit 650 twins all used 3-piece pressed-together (built-up) crankshafts. A new, one-piece forged steel crank was introduced in 1958, along with a stronger clutch.
BONNEVILLE IS COMING
As an interesting sidenote, it was the availability of the new one-piece crank, the Delta Head in twin-carb configuration, and the crazy demand in America for more and more speed that lead to, indeed made inevitable, the arrival of the 650 Bonneville in 1959.

FRAME & RUNNING GEAR CHANGES
The new 8-inch front brake now became a full-width hub with a chromed and louvered end cover. The backing plate now locked into a lug in the fork tube. The front spokes increased in size to match the larger rear spokes. The front forks now had new sliders with more substantial brazed lugs supporting a new central front fender (mudguard) mount, dispensing with front stays, though the rear stays remained. The oil cap was moved to a more upright position so as not to foul the leg when kickstarting. A new anti-theft head steering lock was introduced.

A CRAZY NEW GEARBOX
Triumph Motorcycles thought it wise to introduce to the world its new "Slickshift" mechanism, that allowed clutchless shifts. It never worked very well and was a flop. The driveside chaincase was modified to accept a new oil seal aimed at stopping oil transfer between the crankcase & the primary. Also a new rubber sleeve was installed on the kickstart shaft to try to stem oil leakage.

1958 Triumph TR6 SPECIFICATIONS


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 drive sprockets

Frame Type

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Tire, front

Tire, rear

Wheelbase

Seat Height

Ground Clearance

Fuel capacity

Dry weight

Air-cooled OHV vertical twin, non-unit

649cc / 40.0 ci

71mm X 82mm / 2.79" X 3.23"

8.5:1 (US & export); 7.0:1 (UK)

1-Amal Monobloc

Lucas magneto

42 bhp @ 6500 rpm

1/2" X .335" X 5/16" chain, 70 links

21T X 43T

Multi-plate, wet

4-speed constant mesh, right foot shift


11.2:1

7.8:1

5.5:1

4.6:1

5/8" X .400" X 3/8" chain, 101 links

18T X 43T

Brazed lug, rigid

Telescopic fork, hydraulic damping

Swing arm, 2 Girling dampers

8" SLS drum

7" SLS drum

3.25" X 19" Dunlop

4.00" X 18" Dunlop

55.25" / 140 cm

30.5" / 77 cm

5" / 12.7 cm

3 Imp gal (US); 4 Imp gal (UK & export)

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

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


TALES OF TRIUMPH MOTORCYCLES & THE MERIDEN FACTORY


COMPLETE BOOK OF CLASSIC & MODERN TRIUMPHS


TRIUMPH BONNEVILLE & TR6


TRIUMPH MOTORCYCLES, THEIR RENAISSANCE & THE HINKLEY FACTORY


BONNIE: THE DEVELOPMENT OF THE TRIUMPH BONNEVILLE


TRIUMPH SPEED TWIN & THUNDERBIRD BIBLE


HINKLEY TRIUMPH TRIPLES & FOURS ESSENTIAL BUYERS GUIDE


TRIUMPH PRODUCTION TESTERS’ TALES FROM THE MERIDEN FACTORY


TURNER’S TRIUMPHS: EDWARD TURNER & HIS TRIUMPH MOTORCYCLES


TRIUMPH TROPHY BIBLE


HINKLEY TRIUMPHS, THE FIRST GENERATION


BONNIE: THE DEVELOPMENT OF THE TRIUMPH BONNEVILLE


TRIUMPH: A CENTURY OF PASSION & POWER


TRIUMPH TWIN RESTORATION


CONENTRY’S BICYCLE HERITAGE


HOW TO RESTORE YOUR BSA ROCKET III/TRIUMPH TRIDENT


TRIUMPH & BSA TRIPLES: THE COMPLETE STORY OF THE TRIDENT & ROCKET 3


TIGER CUB BIBLE


TRIUMPH SINGLES: EARLY DAYS TO 1974 BY ROY BACON


BRITISH MOTORCYCLES: TRIUMPH


TRIUMPH MOTORCYCLE RESTORATION, PRE-UNIT


TRIUMPH PRE-UNIT TR5, 5T, 6T, T100 & T110 FACTORY SHOP MANUAL


TRIUMPH MOTORCYCLE RESTORATION


ILLUSTRATED TRIUMPH MOTORCYCLE BUYER’S GUIDE BY ROY BACON


FACTORY ORIGINAL TRIUMPH TWINS 1938-1962


TRIUMPH BONNEVILLE: PORTRAIT OF A LEGEND


TRIUMPH 650 & 750 TWIN REPAIR MANUAL 1963-1983, BY HAYNES


TRIUMPH MOTORCYCLES IN AMERICA


TRIUMPH BONNEVILLE 2001-2012 REPAIR MANUAL BY HAYNES


TRIUMPH BONNEVILLE: THE ESSENTIAL BUYERS GUIDE


TRIUMPH MOTORCYCLES TWINS & TRIPLES


TRUIMPH MOTORCYCLES: FROM SPEED TWIN TO BONNEVILLE


BOOK OF TRIUMPH TWINS BY CLYMER


TRIUMPH BONNEVILLE BIBLE, ALL MODELS 1959-1983


TRIUMPH TIGER CUB & TERRIER 1952-1968 REPAIR MANUAL BY HAYNES


TRIUMPH RACING MOTORCYCLES IN AMERICA


TRIUMPH MOTORCYCLES ILLUSTRATED WORKSHOP MANUAL 1945-1955 BY CLYMER


TRIUMPH 675 DAYTONA & STREET TRIPLE REPAIR MANUAL, 2006-2010


TRIUMPH TRIPLES & FOURS 1991-2004, HAYNES REPAIR MANAUL


TRIUMPH 350 & 500 UNIT TWINS ESSENTIAL BUYERS GUIDE


TRIUMPH TWIN RESTORATION BY ROY BACON


TRIUMPH BONNEVILLE & TR6 MOTORCYCLE RESTORATION GUIDE


TRIUMPH: RETURN OF THE LEGEND


BSA & TRIUMPH TRIPLES: GOLD PORTFOLIO


TRIUMPH MOTORCYCLE RESTORATION GUIDE: BONNEVILLE & TR6


TRIUMPH THUNDERBIRD 6T ROAD TEST 1966


TRIUMPH 500-750 TWINS 1963-1979, SERVICE, REPAIR & PERFORMANCE MANUAL


TRIUMPH TRIPLES


HOW TO RESTORE TRIUMPH TR5/250 & TR6


HOW TO RESTORE TRIUMPH TRIDENT T150/T160


TRIUMPH THRUXTON BONNEVILLE 1959-1969


TRIUMPH TIGER 800 SERVICE MANUAL 2010-2014, HAYNES


TRIUMPH TT600 MOTORCYCLE SERVICE MANUAL


TRIUMPH MOTORCYCLES


ORIGINAL TRIUMPH BONNEVILLE


TRIUMPH, BY ROY BACON


TRIUMPH ILLUSTRATED WORKSHOP MANUAL 1937-1951 BY ROY BACON


TRIUMPH 500 UNIT TWINS 1958-1973 REPAIR MANUAL, BY HAYNES


TRIUMPH T110R DAYTONA 1966-1969


TRIUMPH OWNERS MANUAL: UNIT CONSTRUCTION 350 & 500 TWINS

TRIUMPH INSTRUCTION MANUAL: TRW 499cc SV TWIN


TRIUMPH SPEED TWIN INSTRUCTION BOOK FOR 1939


TRIUMPH BONNEVILLE YEAR-BY-YEAR


CHILTON’S TRIUMPH MOTORCYCLE REPAIR & TUN-UP GUIDE


2010-14 TRIUMPH TIGER 800 HAYNES SERVICE MANUAL


TRIUMPH 650 & 750 TWINS: BONNEVILLE, TIGER, TROPHY & THUNDERBIRD


TRIUMPH MOTORCYCLE RESTORATION: PRE-UNIT, BY TIM REMUS


TRIUMPH MOTORCYCLE RESTORATION, BY TIM REMUS


TRIUMPH BONNEVILLE ROAD TEST PORTFOLIO, 2001-2008


TRIUMPH TRIDENT & BSA ROCKET 3 OWNERS WORKSHOP MANUAL, BY HAYNES


HINKLEY TRIUMPHS: THE FIRST GENERATION


TRIUMPH FUEL INJECTED TRIPLES 1997-2000


TRIUMPH SINGLES: EARLY DAYS TO 1974, BY ROY BACON


TRIUMPH PRE-UNIT TWINS WORKSHOP MANUAL, BY HAYNES


TRIUMPH DAYTONA, SPEED TRIPLE, SPRINT & TIGER 1995-2005 HAYNES SHOP MANUAL


TRIUMPH TIGER 100 & DAYTONA


McQUEEN’S MACHINES: THE CARS & BIKES OF A HOLLYWOOD ICON


TRIUMPH TWENTY-ONE TO DAYTONA: THE C-CLASS 350 & 500 TWINS


TRIUMPH 750/900 TRIPLES & 1200 FOUR 1991-1999 HAYNES REPAIR MANUAL


TRIUMPH, THE LEGENDS SERIES


TRIUMPH MOTORCYCLES & CUSTOM BIKES


TRIUMPH MOTORCYCLES TWINS & TRIPLES, BY REMUS


TRIUMPH MOTORCYCLES: THEIR RENAISSANCE & THE HINKLEY FACTORY


TRIUMPH MOTORCYCLES FROM 1950-1988


TRIUMPH MOTORCYCLES: THE GOLDEN YEARS


THE SCRAPBOOK SERIES I - TRIUMPH


TRIUMPH DAYTONA 1991-2006 ROAD TEST PORTFOLIO


CYCLE WORLD ON TRIUMPH 1967-1972


TRIUMPH SPEED TWIN & THUNDERBIRD BIBLE


TRIUMPH BONNEVILLE: T120/T140, BY HAYNES


SAVE THE BONNEVILLE: THE INSIDE STORY OF THE MERIDEN CO-OP


TRIUMPH: THE RACING STORY


TRIUMPH PRE-UNIT TWINS


LITTLE BOOK OF BRITISH MOTORCYCLES: TRIUMPH


CHILTON’S NEW REPAIR & TUNE-UP GUIDE FOR TRIUMPH MOTORCYCLES


THE TRIUMPH STORY: RACING & PRODUCTION MODELS 1902 TO PRESENT


TRIUMPH 1050 SPRINT, SPEED TRIPLE & TIGER, HAYNES REPAIR MANUAL


ILLUSTRATED TRIUMPH MOTORCYCLE BUYERS GUIDE POST-1945, ROY BACON


COMPLETE BOOK OF CLASSIC & MODERN TRIUMPHS


TRIUMPH BONNEVILLE


TIGER 100/DAYTONA: DEVEOPMENT HISTORY OF THE 500 TWIN


TOURING TRIUMPH TWINS, 3T, 5T, 6T, 3TA & 5TA, 1938-1966 BY ROY BACON


FACTORY TRIUMPH MOTORCYCLE SERVICE MANUAL


TRIUMPH CYCLES PATENT COLLECTION


TRIUMPH MOTORCYCLE OWNERS HANDBOOK, ALL MODELS 1937-1951


TRIUMPH MOTORCYCLES: A PRACTICAL GUIDE TO ALL MODELS FROM 1937




CHILTON’S REPAIR & TUNE-UP GUIDE, TRIUMPH THROUGH 1972


OVERHAUL MANUAL FOR TRIUMPH 3-CYLINDER ENGINE


TRIUMPH BONNEVILLE T120, 1959-1974, BY ROY BACON


TRIUMPH TIGER T100 & T110, 1939-1961, BY ROY BACON


TRIUMPH T90 & T100 UNIT TWINS, 1960-1974, BY ROY BACON


TRIUMPH REPLACEMENT PARTS CATALOGUE, 1972 TRIDENT T150


TRIUMPH TRIDENT SUPER PROFILE


TRIUMPH BONNEVILLE GOLD PORTFOLIO, 1959-1983


1969 TRIUMPH TROPHY 250 REPLACEMENT PARTS CATALOGUE


TRIUMPH 650 & 750 TWIN OWNERS WORKSHOP MANUAL


TRIUMPH: RED HOT BIKES


1966 TRIUMPH REPLACEMENT PARTS CATALOG #6: 3TA, 5TA, T90 & T100S/S


1961 TRIUMPH REPLACEMENT PARTS CATALOG: TWNETY-ONE, SPEED TWIN, TIGER 100


BONNEVILLE: THE WORLD’S FASTEST MOTORCYCLES


TRIUMPH WORKSHOP MANUAL FOR 750 BONNEVILLE & TIGER


TRIUMPH BONNEVILLE & TR6 BY TIM REMUS


TRIUMPH 650 & 750 UNIT TWINS 1963-1983, HAYNES REPAIR MANUAL


TRIUMPH OWNERS HANDBOOK FOR 1973 BONNEVILLE & TIGER


TRIUMPH PRE-UNIT TWINS WORKSHOP MANUAL


TRIUMPH 350/500 TWINS WORKSHOP MANUAL



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