Tech Focus: Spanners and Sockets

Join us on a whistle-stop tour of the many options available when choosing a humble spanner or socket.

An in-depth guide to sockets and spanners, the cornerstone of any toolbox and something of a potential minefield.

Spanners and sockets are without doubt the core element of any mechanic's toolbox, whether you are working on cars for a living or as a hobby and just for fun. At first sight a feature solely on these tools might seem a little ambitious, but as you will hopefully discover, there is a whole lot more to the subject than simply 'metric or imperial.'

In fact there are tools of all shapes and sizes, reflecting the many and varied ways that access to fasteners can be obscured in a cramped engine bay, and you really can't have too many spanners. You may only need that C-spanner or the extra thin stubby 1/ 2in once in a blue moon, but if you have it to hand when that blue moon rises, then it can save you a world of grief in terms of lost time, damaged fixings and skinned knuckles.

Often people will find they don't have that special tool to hand, and they have to improvise instead. We are not recommending you do this, but if you are caught short on a Sunday afternoon and need the job finished so you can use the car for work on Monday, needs must... However, if you do have to make a ‘special’ tool by, for example, grinding a spanner down to gain access for a particular fastening, then keep that as a special tool and replace it in your tool box with a new and undamaged regular spanner as soon as you can.

We should also sound a note of caution about other jobs that fall in a similar category, such as using a second spanner or a bar to gain extra leverage. Again this is not something we can recommend or that the tool manufacturers would condone, but we are all aware that it happens and so it cannot be swept under the carpet. Just be aware that if you are using leverage in this way to apply extra force, then that will most likely exceed the tool's design parameters and it could snap. And if you are applying additional force at the time, then your knuckles are going to move with increased speed towards the nearest obstacle. You have been warned.

To help guide us through the maze of spanners and sockets on offer, we visited Charlie Dunn at Teng Tools, and we are very grateful for his mix of down to earth practical advice and technical knowledge which have been an invaluable help in the compilation of this feature.

Sockets and ratchets

Let’s start with the basics. Sockets generally come in two lengths: standard and deep. There is no difference between them apart from the length. The deep sockets will be needed where, for example, a bolt or stud protrudes so far though a nut that it stops the ratchet head or extension bar from being inserted. In such cases, don’t be tempted to use a socket that is a little bit too short so that you can only insert the extension bar or ratchet part way into it – that is not so bad if you are just spinning a nut on or off, but the danger is to your hand if you are applying force and it slips.

Additionally there are regular sockets, and also impact sockets which are hardened for use with impact tools. Impact sockets are always black from the heat treatment process rather than silver and have no chrome plating or polished finish, although as Charlie notes: 'Our regular tools all have a satin finish nowadays. Chrome plating is environmentally unsuitable, so polishing is the way ahead. There is no getting away from the fact that rust protection from polishing is not quite as good, but this is the way everybody is having to go. With regards the impact sockets, people do use guns with regular sockets and usually the socket will take it, but if they do break then it can be dangerous. They don’t tend to explode and fire off shrapnel, but the danger lies in the fact that you will be applying considerable extra force when it does let go.'

There is one other distinct type of socket, and that is one designed for use with spark plugs. This will have a rubber insert that grips the plug. That can be crucial if you are using an extension to reach a deeply recessed plug, otherwise how do you get it out and back in? It also serves to protect the vulnerable ceramic of the spark plug.

Impact sockets will invariably be six-sided for strength and grip under extreme force, but regular sockets come as either six-sided (hex) or 12-sided (bi-hex). Ultimately the 12-sided socket is more likely to round off an extremely stubborn fitting, but they are also more versatile (sometimes you just can’t get the 6-point on if access is restricted but a 12-point will do the trick), perfectly safe to use in most circumstances and generally the default option. 'On air- cooled engines the extra versatility of a 12-point socket can be a particular bonus when the cylinder fins get in the way,' adds Charlie. 'And our sockets are all hip drive, which means they grip on the middle of the flats rather than the corners. You can see if a tool grips the flats like this by the way the sides are not straight, but curve in slightly. That is particularly useful if a nut is damaged in any way. It also gives a little more wiggle room, as do extension bars with a ‘wobble’ end.'

When building up a tool kit, most people will begin by buying a socket set, and it is the selection of tools in the set as well as the socket sizes that will determine which kit you go for. Obviously you will need to decide between imperial, unified or metric sizes depending on the cars upon which you work, though some kits will include both metric and unified. (As we saw last issue in

the nuts and bolts feature, most of us refer to unified – UNF and UNC

– as imperial, though strictly speaking that refers to the old UK standards such as British Standard Whitworth/ BSW, British Standard Fine/ BSF and BA.) The maximum socket size in the kit will be important to some people too, though you may find it more costeffective to buy a smaller set initially and add a couple of specific additional sockets to it later as and when required.

The quality of the socket set's storage container may be more important than you realise, too. One where the tools can rattle around makes it a nightmare to find the right tool quickly, whereas a quality case that holds each item in a specific place ensures that everything is at your fingertips when needed. This can be a real bonus if you need to transport your tools to a lock-up before starting work. And it is not just about efficiency of working, but safety too. 'If everything has a place,' says Charlie, 'then not only can you see can instantly see where it goes, but you can also see if it is missing! That came from the aircraft industry because obviously you couldn’t risk leaving a tool in an aircraft engine. Garages are leaning more and more towards it too, and it is why our kits are supplied in cases or trays where every tool has a clearly defined place.' When choosing a socket set, there are

three main socket drive sizes for car restoration:

1/4in, 3/8in and

1/ 2in drive. You can get

3/4in drive too, but that tends to be mostly for buses and HGVs. 1/4in sockets are always the thinnest, and a good one will not be much thicker than a box spanner. People fresh to spannering tend to think that 1/ 2in will necessarily be better because it is bigger, but most car mechanics use the smaller sizes for ease of access and only reach for 1/ 2in drive to tackle the bigger stuff. The weakest link is always the ratchet – a 1/4in 43-tooth ratchet can be very strong, but as a consequence it is fairly agricultural and you can hear and feel it clicking around. Finer ratchets will have up to 72 teeth, and while one of these will not be ultimately as strong, it will allow you to work in a more confined space as the arc needed to swing the handle to move from one tooth to the next is smaller. You can also get clutchless ratchets that don’t click and require minimal turning to work, though they are more expensive and again not ultimately as strong. But as Charlie advises: 'To preserve your tools as much as possible, it is good practice not to start undoing a nut with the ratchet, but to begin instead with a solid bar for strength and then switch to the ratchet for speed. The ratchet will do the whole job, but there is always more of a risk of exceeding its safe limits.'

A useful feature on a ratchet is a flexible head, which allows you to use it in a greater variety of positions. 'Teng's bigger 1/ 2in drive one goes in five positions, for example,' says Charlie, 'while the smaller one has many more positions. 'We also do a small kit with a 1/4in ratchet – boiler engineers love these! Despite its size, this is in fact quite a tough little kit with a 60-tooth ratchet that can take both sockets and bits. Ours holds the bits in by magnetism, which can be useful when working in an awkward position like behind a dash. A kit like this is great to keep in the glovebox for emergencies, the only problem being that so many kits these days are only metric, and many suppliers have a much smaller range of imperial or unified sets, while kits that include both metric and imperial are inevitably bigger.'

Other useful pieces of kit in socket sets include universal joints that help you work around obstructions, and size adaptors that will allow one size of ratchet to fit a different drive-size of socket. 'Universal joints may look like the weakest part of the chain,' adds Charlie, 'but we never get them back. It is

usually the size adaptors that go first, but that is better than splitting the socket – you do have to have some weak point designed into the chain.'

Some socket sets will also include a Tommy bar, essentially a solid bar instead of a ratchet. These can be used to start particularly stubborn fixings as you can safely apply more force, but they will be more awkward to use in a confined space. You can also get small thumb ratchets. Again these are not ideal for freeing off a nut, but they are perfect for working up behind a dash once you have cranked the fastening loose.

Breaker bars are essentially like Tommy bars with some movement to the head – not rotationally like the ratchet, but up and down to help clear obstacles. They come in different lengths and the longer they are, the more force you can apply. These can be particularly useful on parts that have not been separated for 40 years, and they give you a better feel than an impact wrench for if a thread is starting to go and you need to back off. Ratchets that have a push-through bar instead of a switch can work in a more confined space than a breaker bar, but also be stronger than a reversible ratchet.

One final tool to mention here is the torque wrench, used for tightening fastenings up to a specific torque setting. 'We do two ranges,' says Charlie. 'On the less expensive ones you must remember to release the tension after use or the tool can take a set. The more expensive tools do not have to be wound off after use because a different material is used in the spring. Torque wrenches can display different scales – you can convert from one to the other, but some have more than one scale. You will usually need more than one, for example one tool to cover 0-25Nm and another for 25-100Nm. Ideally they should be checked once a year or every 600 pulls. The acceptable tolerance is +/- 4%.'

Spanners

Moving on now to spanners, the two main types are open ended and ring. Tools with a different sized open jaw at either end used to be common, but these days they have largely been replaced by combination spanners which have an open jaw at one end and the same size of ring at the other. You can also get double ring spanners which tend to be heavily offset. As with the sockets outlined earlier, non-slip designs with flank drive are becoming popular too.

Starting with the open-ended spanners, Charlie advises: 'On cheaper spanners, the danger is that the jaws will spread. It has to be a good fit to start with and you can check that by feeling for slack, but the metal has to be strong enough not to spread. The difference between a good and a bad spanner is generally in how many times it goes through the case-hardening process. You can’t see that, so you have to buy on trust and this is where a good brand name can give some assurance of quality.'

Combination spanners almost always have an offset ring, which will give a little more clearance for your knuckle if you should slip. Often these are used to hold a bolt head while using a socket on the nut, but they are the essential starter spanners. As with the sockets we looked at earlier, the cheapest way to get started is to buy a set, and one of the factors determining the

Sockets may be deep (on left) or regular length.

Spark plug socket has rubber insert.

Sockets may be 12 sided (bi-hex) or six sided.

Adjustable angle for ratchet head is useful.

Impact sockets are invariably black.

Small kits are great for the glovebox, but are usually only metric.

ABOVE: Extension bars may be a straight fit (top), or have a rounded (wobble) end that allows them to be inserted at a modest angle.

Thumbwheels and mini ratchets apply little force, but can speed up work.

ABOVE: Useful additions to a kit can be universal joints, size adaptors and drive dogs that can be turned using a solid bar .

Regular and stubby combination spanners.

A breaker bar can be used to apply considerable force.

Torque wrenches need regular checking for accuracy. A push-through bar can be stronger than a reversible ratchet.

Flare nut wrenches are perfect for undoing brass unions on brake pipes.

The traditional doubleended open jaw spanner.

Curved edges mean a hip/flank/wall drive.

Double-ended ring spanners tend to be heavily offset.

A flexible box end ring spanner set from Teng.

A ratchet spanner with a flexible head.