1958 Triumph Thunderbird


1958 Triumph Thunderbird

ABOVE: The 1958 Triumph Thunderbird 6T looked very similar to this 1958 Triumph T110 Tiger, with headlight nacelle and full fenders. We need good photos of a ’58 T-bird. If you own one, please send us pictures of YOUR BIKE!

RACING WINS FOR TRIUMPH
1958 was a very good year for Triumph Motorcycles. On the road race circuit, Triumph twins were finally beating BSA Gold Stars, with an overall victory for the 650 twin at the last Thruxton 500-miler. Of course, this work was done by the lightning-fast Tiger T110, not the humble 6T Thunderbird. In fact, the first twin-carb Delta heads began appearing on T110s in competition & were soon available to privateers through their local Triumph dealers. This was the precursor to the legendary Triumph Bonneville, to arrive in 1959.

MINOR CHANGES FOR THE 1958 TRIUMPH THUNDERBIRD
While the sporty T110 got several performance upgrades, such as a new 8-inch full-width front brake, the bread-and-butter Thunderbird got passed over for most of it. The headlight nacelle was changed slightly, now the same as that used on the 5T 500 twin models, but differing slightly from those of the T100 and T110. The nacelle also now incorporated rubber grommeted holes in back for cables & wiring runs & the clutch & front brake cables now featured knurled finger-adjusters on the handlebars. The oil filler cap was repositioned out of the way of the leg while kickstarting. A Neiman-type steering head lock was offered as an option. Exhaust pipe diameter was dropped from 1-3/4″ to 1-1/2″.


1958 Triumph Thunderbird 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

34 bhp @ 6500 rpm

1/2″ X .335″ X 5/16″ chain, 70 links

24T X 43T

Multi-plate, wet

4-speed constant mesh, right foot shift

—-

11.9:1

8.25:1

5.81:1

4.88

5/8″ X .400″ X 3/8″ chain, 101 links

18T X 46T

Brazed lug, rigid

Telescopic fork, hydraulic damping

Swing arm, 2 Girling dampers

7″ SLS drum

7″ SLS drum

3.25″ X 19″

3.50″ X 19″

55.75″ / 141 cm

31″ / 77.5 cm

5″ / 12.7 cm

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

395 lbs / 179 kg

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