1972 TRIUMPH TR6


1972 Triumph TR6 Tiger


1972 TRIUMPH TR6 BY THE NUMBERS
1972 was the second year for the Oil-in-Frame. There were four models for 1972: TR6R (the standard Roadster with low pipes); TR6C (with high pipes running along the left side); TR6P (Police version); and TR6RV (a Roadster with optional 5-speed gearbox). Engine & frame numbers ran from JG033084 to EG057252, built from August 20, 1971 to May 17, 1972. The paint color combinations were Polychromatic Blue & Cold While with black lining. The mudguards (fenders) were also painted blue. This was the last year for the Triumph TR6C (the last one to roll off the assemby line was #AG044359.)

ENGINE CHANGES
The new Quaif-derived 5-speed gearbox became optional starting with engine #CG051405, with a "V" added to the end of the model designation. Full-width cam gears were fitted for quieter operation. Starting with engine #XG043810, the cylinder heads were modified to accept a 'push-in' exhaust pipe fitting. Gone were the threaded-in steel flanges which the pipes clamped to. In their place was a new system (presumably designed to save money) that caused all sorts of problems. The heavy engine vibration worked the steep pipes against the soft aluminum heads & 'hogged-out' the holes so that they would wobble around & fail to seal. The solution was to machine threads into the exhaust ports to install the old-style screw-in spigots & clamp the pipes to them, ala 1971 & earlier. I know, because I did this exact same fix on my 1973 TR7 cum Bonneville Cafe Racer, "The Yellow Bike". Starting with #XG043810, new style rocker boxes were fitted which replaced the 4 small screw-in caps with 2 large cover plates, which greatly aided in valve adjustment. Starting with #AG046174, the cylinder head bolts were changed from a hex-head design to an Allen-head that that allowed the top end to be re-torqued without removing the rocker boxes.

1972 triumph tr6, triumph tr6 tiger, triumph tr7, triumph bonneville, triumph motorcycles

GEARBOX MODS
The leaf spring used for indexing the shift cam was replaced with a spring-loaded plunger, as before 1970. Starting with #EG056421, the high gear bearing on the 5-speeds was changed from a 13-roller to an 11-roller, which required a new 5th gear & these are not interchangeable with the old ones. Starting with #CG051405, the clutch shock absorber inner & outer plates were secured by 3 through-bolts, now peened over to prevent loosening.

FRAME IMPROVEMENTS
The new oil-bearing frame introduced in 1971 was not without its problems. A good overall design, it simply wasn't well-engineered by parent-company BSA's "brain trust" at Umberslade Hall, the overly expensive tech center BSA had lavished its dwindling resources on. This new design center was supposed to save the company, when in fact, it hurried its demise. Among the many foibles they made was to make the seat height of the new 1971 oil-bearing frame a staggering 34-1/2 inches from the deck. Too tall for most riders. This was remedied for the 1972 Triumph TR6 with an extensive redesign of the rear frame & all the ancillaries that went with it (side covers, thinner seat, air filters, battery tray, electrical suite, all of it). This dropped the seat a full 2 inches, to 32-1/2 inches. The new seat now hinged from the left, like it was back in 1970. The rear Girling shock absorbers (suspension units) went from 12.9 inches to 12.4. All of these mods were made starting with #CG051405.

1972 UK-spec Triumph TR6

ABOVE: This 1972 Triumph TR6 Tiger sports the squarish UK-spec (3.5 Imperial Gallon) tank, whereas the US-versions had the "teardrop" tank.

CYCLE GEAR
Early 1972 Triumph TR6 models had lower front fork sliders with a rough-cast finish & a 'styling rib' running vertically down their sides. Later '72's got polished lower sliders with no styling rib, a much cleaner look. The front fenders (mudguards) got an extra stay to fight vibration & UK models got a lengthened front fender. The handlebar switch consoles were swapped left-to-right so that now the Left console had directional indicators (turn signals), the the kill switch; and the Right now had the headlight flasher button, horn & headlight dimmer (low & high-beam).

triumph conical hubs, triumph conical brakes, triumph motorcycles, triumph tr6, triumph tr7

COOL CONICAL HUBS
New for the 1971 model year, Triumph introduced these gorgeous conical brake hubs, front & rear, with all new brake hardware. The 8-inch fronts were a TLS (Twin Leading Shoe) design that proved to be nowhere near as effective as the 8" TLS unit it replaced. The pivot arms & cams had poor leverage & being conical in shape, they were not full-width as were the earlier designs. The rear was a 7-inch SLS (Single Leading Shoe), which also had leverage problems. These glitches were sorted out over the 2 model years 1971 & 1972, before the front drums were replaced in 1973 with a long-awaited front disk brake (just 5 years after Honda). One must wonder why they spent what little money they had designing an entirely new front brake when they knew they were going to replace it in a couple of years. Why not just come out with the disk brake in 1971? Alas, we may never know. However, the upside to all this is that we have lots of gorgeous conical hubs running around today, and while they may not be the most effective stopping devices, they are awfully pretty!!



MODEL DESIGNATIONS:
1972 Triumph TR6R................................ Low pipes
1972 Triumph TR6C................................ High Pipes
1972 Triumph TR6P................................ Police
1972 Triumph TR6RV............................... 5-speed

ENGINE:
Engine type....................................... OHV vertical twin
Horsepower at RPM............................ 47 BHP @ 6,700 rpm
Bore................................................ 71mm / 2.79"
Stroke............................................ 82mm / 3.23"
Displacement...................................... 649cc / 40 cu. in.
Compression Ratio................................. 8.5:1
Valve Clearance (cold):
Inlet............................................. 0.05mm / 0.002"
Exhaust........................................... 0.10mm / 0.004"
Valve Timing:
Inlet Valve Opens................................. 34 degrees BTDC
Inlet Valve Closes................................ 55 degrees ABDC
Exhaust Valve Opens............................... 55 degrees BBDC
Exhaust Valve Closes.............................. 34 degrees ATDC

IGNITION:
Contact Breaker Type............................... Lucas 6CA
Ignition Breaker Gap............................... 0.4mm / 0.015"
Spark Plug Type.................................... Champion N3
Spark Plug Gap..................................... 0.64mm / 0.025"
Timing (static).................................... 14 degrees BTDC
Timing (fully advanced):........................... 38 degrees BTDC

CARBURETOR (1):
Type............................................... Amal Concentric R930/60
Throat Size........................................ 30mm
Main Jet........................................... 230
Needle Jet......................................... 106
Needle Position.................................... 2
Needle Type........................................ 622/124
Throttle Valve Cutaway............................. 3-1/2
Pilot Jet.......................................... 25

TRANSMISSION:
Gear Ratios, 4-speed:
4th - Top.......................................... 5.84
3rd - Third........................................ 6.76
2nd - Second....................................... 8.17
1st - Bottom....................................... 11.8
Gear Ratios, 5-speed:
5th - Top.......................................... 4.95
4th - Fourth....................................... 5.89
3rd - Third........................................ 6.92
2nd - Second....................................... 9.07
1st - Bottom....................................... 12.78

CLUTCH:
Type............................................... Multi-plate, wet
Number of Plates:
Drive Plates....................................... 6
Driven Plates...................................... 6

SPROCKETS:
Engine............................................. 29 teeth
Clutch............................................. 58 teeth
Gearbox............................................ 19 teeth
Rear Wheel......................................... 46 teeth

CHAIN:
Primary, pitch..................................... 3/8" duplex
Primary, length.................................... 84 links
Final Drive, pitch................................. 5/8" X .400" X 3/8"
Final Drive, length................................ 106 links

CAPACITIES:
Fuel (US versions)................................ 3 Imp. gal.
Fuel (UK & export versions)........................ 4 Imp. gal.
Oil Tank........................................... 4 pints / 2 L
Gearbox........................................... 1 pt / 500cc
Primary Chaincase............................. 1/4 pt / 150cc
Front Forks....................................... 6.4 oz. / 190cc

TIRES:
Front............................................... 3.25 X 19"
Rear................................................ 4.00 X 18"

SUSPENSION:
Front............................................... Telescopic Forks
Rear................................................ Swing Arm

BRAKES:
Front............................................... 8" / 20.32cm TLS
Rear................................................ 7" / 17.78cm SLS

DIMENSIONS:
Seat Height...................................... 34.5" / 87.3cm
Wheelbase........................................ 56" / 142cm
Length.............................................. 87.5" / 222cm
Width............................................... 29" / 73.5cm
Ground Clearance.............................. 7" / 18cm
Weight, unladen................................ 383 lbs / 173.9kg


Check out these TRIUMPH BOOKS


TRIUMPH BONNEVILLE YEAR-BY-YEAR

TRIUMPH BONNEVILLE ESSENTIAL BUYER’S GUIDE

COMPLETE BOOK OF CLASSIC & MODERN TRIUMPHS

TRIUMPH MOTORCYCLES 1956-1983

FACTORY-ORIGINAL TRIUMPH TWINS

TRIUMPH MOTORCYCLES

TRIUMPH MOTORCYCLE RESTORATION, PRE-UNIT

TALES OF TRIUMPHS & THE MERIDEN FACTORY

TRIUMPH ILLUSTRATED SHOP MANUAL, 1935-1939

TRIUMPH ILLUSTRATED SHOP MANUAL, 1937-1951

TRIUMPH ILLUSTRATED SHOP MANUAL, 1945-1955


For more Great Books, please visit our
MOTORCYCLE BOOK STORE




HOME PAGE
Triumph Motorcycles
BSA Motorcycles
Norton Motorcycles
Matchless-AJS Motorcycles
AMC-Associated Motor Cycles
Royal Enfield Motorcycles
Ariel Motorcycles
Vincent Motorcycles
Velocette Motorcycles
Rickman Motorcycles
Japanese Motorcycles
Cafe Racers
Choppers & Bobbers
Rat Bikes
Classic Racing Motorcycles
Classic Motorcycle Auctions
Classic Motorcycle Shows
Classic Motorcycle Rides
Classic Motorcycle Restoration
Classic Motorcycle Shops
Classic Motorcycle Clubs
Classic Motorcycle Photo Gallery
Classic Motorcycle Events Calendar
Send us Pictures of YOUR BIKE
YOUR BIKE Pictures
About Us
Site Map
CONTACT US
Brit Iron Back Issues
Visit our STORE
Subscribe to our FREE e-zine & get a FREE 11X17 Poster
BACK TO TOP - 1972 Triumph TR6


1972 Triumph TR6
12/1/14

free classified ads, motorcycles for sale

Check out our
FREE
Classifed Ads
BIKES FOR SALE!

facebook page, classic-british-motorcycles.com

Visit our
FACEBOOK PAGE
and "LIKE" us!


Check out these
NEW PAGES:

Triumph Tiger
1939 T100
1947 T100
1939 T100
1949 T100
1950 T100
1952 T100
1953 T100
1955 T100
1958 T110
Norton Manx
1948
1949
1952
1953
1957
1959
1963
Royal Enfield Interceptor
1963
1965
1967
1970
Vincent Black Shadow
1950
1952
1953
1954
Ariel Square Four
1932
1948
1951
1953
1955
1956
1957


CLASSIC TRIUMPHS
2015 Wall Calendar

HISTORIC MOTORCYCLES
2015 Wall Calendar
ULTIMATE MOTORCYCLES
2015 Wall Calendar

Check out all our
MOTORCYCLE CALENDARS



facebook logo, facebook page

Visit our
FACEBOOK PAGE
and "LIKE" us!