1976 Triumph Bonneville


ABOVE: The 1976 Triumph Bonneville is the first to adopt left-side shift. Note shifter coming out of primary case.

SPANISH AMALS?
Engine mods were few. A new muffler set were now almost cylindrical reverse-cones (very little taper) & noise reduction revisions. The twin 30mm Amal Concentric carburetors were now being produced by the company’s Spanish subsidiary & now featured longer ticklers. New petcocks were now clearly marked with ‘ON’ and ‘OFF’ to meet new US regs. To mute intake noise, silencer tubes were installed in the centers of each air filter.

ABOVE: The move to left-shift on the 1976 Triumph Bonneville was the perfect excuse to replace the rear drum with a 19″ disk, interchangeable with the front. Note that these disks have been cross-drilled for lightness and added cooling. Stock disks would have been un-drilled.

LEFTHAND SHIFT: IT AIN’T RIGHT!
But the biggest change on the 1976 Triumph Bonneville surely was the switch from right-hand shift (the way it traditionally had always been on virtually all foot-shift British & European motorcycles, as well as Sportster; and the way God intended it to be) to left-hand shift again to meet US legislation. This was accomplished with a cross-over shaft, crooked to clear the clutch, which extended through the gearbox and into the center of the primary case, between the clutch & the engine sprocket. From there it passed through the primary cover (a new piece) where it mounted the shifter on its splined end. This all required new inner & outer gearbox covers, bushings, gearbox quadrant, kickstart shaft & primary cover. Many thought it ruined the look of the bike. That beautifully sculpted primary cover was now marred by a shift pedal & the gearbox cover on the other side was conspicuously lacking. It just didn’t seem right.

ABOVE: Note the revised gearbox cover, which is now missing its shifter.

1976 TRIUMPH BONNEVILLE REAR DISK BRAKE
When the shifter moved to the left, the brake pedal moved to the right. Rather than work up a new linkage for the rear brake, Triumph took this opportunity to introduce a hydraulic disk brake. The underslung Lockheed caliper was operated via a remotely-operated master cylinder hidden under the seat. Both front & rear disk brakes were identical 10″ cast iron units (the front slightly thinner than before & sans the chrome plating).

FRAME
Frame modifications were restricted to those needed to accomodate the new rear disk brake & right-hand brake. While regs were heating up in the US, this same year the UK dropped its age-old requirement for a front license plate on motorcycles, the typical ones you saw on front fenders. So the front fenders were no longer drilled for them. Switchgear was now labeled, with the lefthand control displaying cast-in labels, while the righthand control & the headlight shell had cheesy stick-on labels that fell off.

NEW COLORS
The Meriden Co-op struggling as they were just to get the assembly line rolling again, very few changes were made unless absolutely necessary to meet pending regs. Hence the color combos remained as they were in 1974 & 1975, for part of the year & Photochromatic Red & Cold White for US & UK markets and also Photochromatic Blue & Cold White as a UK option. But gone was the 650cc T120, after 25 years of service, only the 750cc T140 remained.


1976 Triumph Bonneville SPECIFICATIONS

T120RV Bonneville

T140RV Bonneville

Engine type

Displacement

Bore & Stroke

Compression

Carburetors

Ignition

Engine output

Primary drive

Primary sprockets

Clutch

Gearbox

Ratios, overall:

1st, bottom

2nd

3rd

4th

5th, top

Final drive

Final drive sprockets

Frame type

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Tire, front

Tire, rear

Fuel capacity

Wheelbase

Seat height

Ground clearance

Weight

5-speed 650 Roadster

5-speed 750 Roadster

Air-cooled OHV vertical twin

744cc / 45.0 ci

76mm X 82mm / 2.99″ X 3.23″

8.6:1

2- Amal Concentrics R930/9, 30mm

Battery & coil, Lucas

49 bhp @ 6200 rpm

3/8″ triplex X 84 links

Engine 29T X Clutch 58T

Multi-plate, wet

5-speed constant-mesh, left-foot shift

12.25:1

8.63:1

6.58:1

5.59:1

4.7:1

5/5″ X .400″ X 3/8″ chain X 106 links

Gearbox 19T X Rear 47T

All-welded, oil-bearing large-tube backbone

Telescopic fork, hydraulic damping 2-way

Swing arm, 2 Girling dampers

10″ disk, 2-piston hydraulic caliper

10″ disk, 2-piston hydraulic caliper

3.25″ X 19″ Dunlop, ribbed

4.00″ X 18″ Dunlop, universal

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

54.5″ / 140.3 cm

32.5″ / 77.5 cm

5″ / 12.7 cm

387 lbs/ 176 kg

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