Wrenches & Spanners Origins
How open-end, box-end, combination and adjustable wrenches developed for automotive work.
Why do some older American cars require Whitworth or British-sized wrenches?
Short answer: British-built cars and motorcycles used Whitworth and later British Standard Fine fastener sizes well into the twentieth century.
British-built cars and motorcycles used Whitworth and later British Standard Fine fastener sizes well into the twentieth century. Restorers of vintage British vehicles still need Whitworth wrenches, because neither SAE fractional nor metric tools fit those hex sizes properly.
When did metric wrenches become necessary in American repair shops?
Short answer: Metric wrenches became necessary as imported cars grew popular in the 1960s and 1970s, and as U.S. automakers began switching their own designs to metric fasteners during the 1970s and 1980s.
Metric wrenches became necessary as imported cars grew popular in the 1960s and 1970s, and as U.S. automakers began switching their own designs to metric fasteners during the 1970s and 1980s. Today most professional technicians carry full SAE and metric sets because both standards still appear on vehicles in service.
Why do professional technicians still keep SAE wrenches?
Short answer: Many older domestic vehicles, classic cars, trucks, trailers and some equipment still use SAE fractional fasteners.
Many older domestic vehicles, classic cars, trucks, trailers and some equipment still use SAE fractional fasteners. Keeping both SAE and metric wrenches lets a shop service the full range of vehicles that come through the door, which is why mixed sets remain standard decades after the metric transition.
When did stubby wrenches become popular with mechanics?
Short answer: Stubby combination wrenches spread in the late twentieth century as vehicle designs packed more components into smaller engine bays.
Stubby combination wrenches spread in the late twentieth century as vehicle designs packed more components into smaller engine bays. Their short handles reached fasteners where a full-length wrench could not swing.
Where did striking wrenches come from?
Short answer: Striking wrenches, also called slugging wrenches, have a heavy box end and a pad meant to be hit with a hammer.
Striking wrenches, also called slugging wrenches, have a heavy box end and a pad meant to be hit with a hammer. They came from heavy industry, railroading and shipbuilding, and they are still used on large truck and equipment fasteners.
Why did older tool catalogs list S-shaped wrenches?
Short answer: S-wrenches have curved handles that offset their two open ends, letting them reach around obstacles.
S-wrenches have curved handles that offset their two open ends, letting them reach around obstacles. Older tool catalogs commonly listed them, and some vintage automotive kits included them for manifold and carburetor nuts. Ratcheting wrenches and socket extensions later took over many of those jobs.
How did drop forging improve wrenches?
Short answer: Drop forging shapes heated steel between dies under heavy impact, aligning the grain of the metal with the shape of the tool.
Drop forging shapes heated steel between dies under heavy impact, aligning the grain of the metal with the shape of the tool. Forged wrenches became the industry standard because they are much stronger and more durable than cast or stamped tools, which matters when technicians apply high torque.
Why were stamped wrenches included with many early tool kits?
Short answer: Stamped steel wrenches were inexpensive to produce, so manufacturers often included them in tool kits supplied with cars, bicycles and machinery.
Stamped steel wrenches were inexpensive to produce, so manufacturers often included them in tool kits supplied with cars, bicycles and machinery. They were adequate for occasional light use, but professional mechanics generally preferred forged wrenches because stamped ones bend and spread more easily under load.
Why do British repair manuals say spanner instead of wrench?
Short answer: "Spanner" is the British English term for a wrench, and it appears throughout British and Commonwealth automotive literature.
"Spanner" is the British English term for a wrench, and it appears throughout British and Commonwealth automotive literature. Reading older British service manuals requires knowing that spanners and wrenches describe the same family of tools.
Why did hook spanners appear in vehicle tool kits?
Short answer: Hook spanners engage notches on the edge of round nuts.
Hook spanners engage notches on the edge of round nuts. They appeared in vehicle and motorcycle tool kits for adjusting items like steering head bearings, suspension preload collars and some wheel bearing nuts.
How did ratcheting wrenches change work in tight engine bays?
Short answer: Engine bays became more crowded as cars added emissions equipment, power accessories and front-wheel-drive layouts.
Engine bays became more crowded as cars added emissions equipment, power accessories and front-wheel-drive layouts. Ratcheting box wrenches, which spread widely from the late twentieth century, let technicians turn fasteners with short swings instead of repositioning a standard wrench each turn.
What did a basic mechanic's wrench set look like in the early twentieth century?
Short answer: A typical early-twentieth-century mechanic owned adjustable screw wrenches, a few open-end wrenches, perhaps a pipe wrench and some tappet wrenches.
A typical early-twentieth-century mechanic owned adjustable screw wrenches, a few open-end wrenches, perhaps a pipe wrench and some tappet wrenches. Socket sets and full combination wrench sets became common later, as interchangeable sockets and standardized fastener sizes spread through the industry.
Why are some vintage wrenches marked with two sizes on each end?
Short answer: Many vintage open-end wrenches had a different size on each end so one tool covered two fasteners.
Many vintage open-end wrenches had a different size on each end so one tool covered two fasteners. This kept tool kits smaller, and double-open-end wrenches remained common in sets for decades before combination wrenches became the professional norm.
How long have open-end wrench heads been angled at about 15 degrees?
Short answer: Most open-end wrench heads are angled, commonly about 15 degrees, so the wrench can be flipped over to reach a new position in a tight space.
Most open-end wrench heads are angled, commonly about 15 degrees, so the wrench can be flipped over to reach a new position in a tight space. That simple design feature has been standard for many decades because it effectively doubles the usable positions when swing room is limited.
Why did line wrenches become a separate tool category from pipe wrenches?
Short answer: Pipe wrenches grip round pipe with serrated jaws, which would crush a soft brake or fuel line fitting.
Pipe wrenches grip round pipe with serrated jaws, which would crush a soft brake or fuel line fitting. As hydraulic brakes and pressurized fuel lines spread, toolmakers sold flare nut or "tubing" wrenches as a separate category for tube fittings.
General guidance only. Follow the vehicle and tool manufacturer's procedures, and confirm vehicle coverage on the tool maker's list before buying.