1957 Ariel Square Four

1957 ARIEL SQUARE 4 - GETTING LONG IN THE TOOTH
Alas, the world was changing, and with it the motorcycle market. The Ariel Square 4 designed decades before, was keyed to another age, one where acceleration and all-out top speed weren't as important as smoothness and reliability. Hence the Square Four engine was built around these parameters. Two counter-rotating crankshafts not only gave it its name, but also provided a level of smoothness that was mostly unavailable in that era. But it came at a price. Two crankshafts are heavier than one, so double the rotating mass must have hurt performance. Also, the head was designed, automotive-style, with a long, torturous route that the intake tract had to follow in order to feed all four cylinders. By this late stage in the game, the Square Four was now sporting an auto-industry-derived SU carburetor, but it wasn't nearly enough. The horsepower of this 1000cc 4-cylinder hovered around 40hp, good for a claimed 100 mph, but it took its time getting there, for sure. The market was moving toward all-out performance, even at the cost of reliability and vibration in some cases. Free-revving vertical twins like the Triumph Tiger and Norton Dominator became the standard, and Ariel was able to nothing to counter it. No new bikes were coming. These last few years of series production saw sale steadily dwindle until by 1959, it was all over for the Ariel Square Four.


1957 Ariel Square Four SPECIFICATIONS


Engine type

Displacement

Bore & Stroke

Compression

Carburetor

Engine output

Ignition

Charging

Battery

Primary drive

Clutch

Gearbox

Ratios, overall:

1st, bottom

2nd

3rd

4th, top

Final drive

Frame type

Suspension, front

Suspension, rear

Brake, front

Brake, rear

Wheel, font

Wheel, rear

Tire, front

Tire, rear

Fuel capacity

Wheelbase

Seat height

Ground clearance

Dry weight

Air-cooled OHV twin-crankshaft 4-cylinder

997cc

65mm X 75mm

7.2:1

1- SU side-draft w/variable choke

42 bhp @ 5800 rpm

Lucas coils & distributor

Lucas 70W dynamo

6 volt, 20 amp-hours

1/2" X .305" chain

Multi-plate, dry

4-speed constant-mesh, right foot shift


11.55:1

7.4:1

5.7:1

4.36:1

5/8" X 3/8" chain

Steel tube, full-cradle

Ariel telescopic fork, hydraulic damping

2- plunger-type w/short trailing arm

7" full-width SLS drum

8" SLS drum

WM2-19  (19")

WM3-18  (18")

3.25" X 19" Dunlop, ribbed

4.00" X 18" Dunlop, universal

5 gal

56.0"

31.0", unladen

5.5", unladen

435 lbs

A WORK IN PROGRESS
In our efforts to complete our online index, and make this the world's greatest website about classic British motorcycles, we're building pages as fast as we can. The first thing we add are the pictures. Then come the specifications and then the history. So, if you see a page that just has only pictures on it, or just pictures and specs, please check back in a few weeks to see if we have it done. Thanks for your patience. And thanks for visiting Classic-British-Motorcycles.com. Please tell your friends about us.


MORE ARIELS
Ariel Motorcycles
.....Ariel Square Four
..........1932 Ariel Square Four
..........1948 Ariel Square Four
..........1950 Ariel Square Four
..........1951 Ariel Square Four
..........1952 Ariel Square Four
..........1953 Ariel Square Four
..........1955 Ariel Square Four
..........1956 Ariel Square Four
..........1957 Ariel Square Four
..........1958 Ariel Square Four
..........1959 Ariel Square Four
.....Ariel Red Hunter
..........1939 Ariel Red Hunter
..........1947 Ariel Red Hunter
..........1948 Ariel Red Hunter
..........1949 Ariel Red Hunter
..........1954 Ariel Red Hunter
..........1957 Ariel Red Hunter


Check out these ARIEL BOOKS


ARIEL SQUARE FOUR


ARIEL MOTORCYCLE WORKSHOP MANUAL, 1933-1951


ARIEL, THE COMPLETE STORY


ARIEL SQUARE FOUR SUPER PROFILE


BOOK OF ARIEL LEADER & ARROW, 1958-1966


BOOK OF ARIEL SINGLES, 1939-1960


CLYMER’S SHOP MANUAL FOR ARIEL 1939-1951


ARIEL MOTORCYCLE OWNERS MANUAL, 1933


THE BOOK OF THE ARIEL


ARIEL LEADER/GOLDEN ARROW ROAD TESTS


THE BOOK OF THE ARIEL, 1933-1939


ILLUSTRATED PARTS LIST FOR 1956 ARIEL SINGLES


BLACK ARIELS: VINTAGE ARIELS, 1926-1930






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MOTORCYCLE BOOK STORE


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