Hand tools for mechanics

Sockets before spanners

A socket surrounds a fastener and grips all six flats. A spanner grips two, or four on a ring end. That difference decides whether a tight nut comes undone or rounds off, so where a socket will fit, use one.

Six-point sockets grip better than twelve-point, because each face carries more of the load. Twelve-point exists so you can find purchase every 30 degrees instead of every 60, which matters in a confined space. On anything seized, six-point every time.

Six point

Maximum contact on the flats. The right default, and the only sensible choice on a rusted fastener.

Twelve point

Twice as many engagement positions, less grip. For tight access where a full swing is impossible.

Deep sockets

For a nut on a long stud, where a standard socket bottoms out on the thread before it reaches the flats.

Which drive size for what

The square drive on a ratchet comes in three sizes on a car, and each has a range it is right for. Using a big drive on a small fastener means you cannot feel the resistance, and snapping a bolt is easy. Using a small drive on a big one means breaking the tool.

One-quarter inch handles interior trim, sensors and small brackets. Three-eighths does most engine bay work. Half inch is for suspension, crank bolts and wheel nuts, and it is where a breaker bar belongs.

1/4 inch

Up to about 10mm. Low torque, fine feel, fits where nothing bigger will.

3/8 inch

The workhorse. Roughly 8mm to 19mm, and the drive most engine bay jobs live on.

1/2 inch

Suspension and wheels. Enough section to take a breaker bar without twisting.

Torque is a specification, not a feeling

Plenty of fasteners on a modern car have a stated torque figure, and some are torque-to-yield, meaning they stretch permanently and must be replaced rather than reused. Guessing is how head gaskets fail and how alloy threads strip.

A click-type torque wrench is a measuring instrument. Store it wound back to its lowest setting, never use it to undo anything, and treat a drop on a concrete floor as a reason to have it checked.

Tighten only

Undoing with a torque wrench can load it well past its range and put the calibration out.

Wind it down

Left on a high setting the spring takes a set, and the readings drift low.

Angle matters too

Many modern bolts specify a torque then a further turn in degrees, which needs an angle gauge, not a bigger pull.

Getting a seized fastener out

Rust welds a fastener to its thread, and force alone usually shears it. The sequence that works is penetrating oil and time, then shock rather than steady pull, then heat, and only then more leverage.

Shock is the underrated step. Several sharp taps on the head of a bolt with a hammer break the corrosion bond in a way that pulling harder does not, which is the whole principle behind a hand impact driver.

Soak first

Penetrating oil overnight beats any amount of extra leverage applied dry.

Shock next

Sharp taps crack the rust bond. Pulling harder just stores energy in the bolt until it snaps.

Then heat

Expansion breaks the seal, but keep it away from fuel lines, brake lines and anything plastic nearby.

Where to spend and where not to

Spend on anything that transmits torque to a fastener, because when it fails it takes the fastener with it. A cheap socket that rounds a nut has cost you an hour and possibly a drilling job. A cheap ratchet that skips under load will also take skin off your knuckles.

Save on the things whose failure is merely inconvenient. Trim tools, brushes, drain pans and funnels do the same job whatever they cost.

Buy well

Sockets, ratchets, spanners, torque wrench, extractors. The failure mode is damage to the car, not just the tool.

Buy cheaply

Trim levers, funnels, drain pans, brushes, magnetic trays. Nothing is at risk if they are ordinary.

Buy singly

A 200 piece set is priced on count. You will use around forty of the pieces, and the forty are better bought properly.

Frequently asked questions

What hand tools does a beginner mechanic need?

A 3/8 inch ratchet with a six-point socket set, a combination spanner set, a breaker bar, a torque wrench, screwdrivers including Torx and hex, combination and long-nose pliers, and a trolley jack with axle stands. That covers servicing, brakes and most bolt-on repairs.

Should I buy metric or imperial spanners?

Metric for anything built in the last forty years outside the United States, and for most American cars since the 1980s too. Older American vehicles, and some trailer and agricultural fittings, still need imperial. Buy metric first and add imperial only when a job demands it.

Do I really need a torque wrench?

For wheel nuts, cylinder heads, suspension bolts and anything into aluminium, yes. Those fasteners have specified figures because too little lets them loosen and too much strips the thread or stretches the bolt. For a bracket or a splash guard, feel is fine.

What is the difference between six point and twelve point sockets?

A six-point socket contacts all six flats of the fastener with more surface on each, so it grips harder and is far less likely to round a tight nut. A twelve-point fits every 30 degrees instead of every 60, which helps in confined spaces at the cost of grip.

How do I remove a bolt with a rounded head?

A bolt extractor socket, which has a reverse spiral flute that bites harder as you turn. Failing that, weld or braze a nut on, or drill it out and use a screw extractor. Never keep trying larger sockets, because each attempt removes more of what is left to grip.

What is a breaker bar for when I own a ratchet?

Leverage and survival. A breaker bar is a solid handle with no ratchet mechanism, so there are no pawls to shear under a long hard pull. Use it to crack a fastener loose, then swap to the ratchet to spin it out.

Are cheap socket sets worth buying?

The problem is not that they break, it is that the soft steel deforms and lets the socket slip on the flats, rounding the fastener. That converts a five minute job into a drilling job. Buy a smaller set of decent sockets rather than a large cheap one.

What size sockets do I use most on a car?

On metric vehicles, 10mm, 13mm, 15mm, 17mm and 19mm cover the large majority of bolts you will meet, with 8mm and 12mm close behind. If you buy individually rather than as a set, start with those.