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Using Hand Tools - Spanners and Sockets

Vital information for working on cars

by Julian Edgar

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This article was first published in 2007.

People who have either a formal training in the use of hand tools (eg they’ve done a trade apprenticeship) or who have had a very long experience of using tools (ie they’ve learnt from their mistakes) tend to assume that everyone knows how to use tools. I mean to say, what is there to know about using spanners? Well, quite a lot.

It’s only when you see people who have simply no idea of how to use hand tools that you realise the very real necessity of learning. I remember when I taught automotive mechanics to secondary school students. Not having a ‘trade’ background I wondered if my ignorance would soon show, but I needed have worried. After all, it was only a few lessons into the term that I saw a student using an adjustable shifter to try to remove head bolts... (And for those that wonder at the significance: head bolts are amongst the most tightly torqued of any bolts in a car... you need a well-fitting socket and a long lever to undo them.)

Knowing how to use tools has two major advantages. (1) You’re more likely to readily achieve success; (2) You’re less likely to damage the equipment you’re working on. And those two points are related: round-off the head of a nut you’re trying to undo with the wrong tool and/or technique and you’ll find success terribly elusive...

Undoing and Doing-Up Nuts and Bolts

The two proper ways of undoing (and doing-up) nuts and bolts are with spanners and sockets. Aside from the different sizes, spanners come in two basic types: ring and open-ended. Both ring spanners and sockets can be either 6 or 12 point. The number of ‘points’ refers to the number of flats on the inside of the ring spanner or socket.

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A 6-point design has a hexagonal shape...

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... a 12-point design has twice as many internal flats.

Six-point sockets and spanners are usually cheaper and are less likely to slip (ie round-off the nut or bolt) but they have a major disadvantage in that they cannot be applied at as many rotational angles. In other words, a 6-point ring spanner may not be able to be fitted on the nut or bolt as the length of the spanner may foul something. In the same location, a 12 point spanner will fit.

Absolutely vital in successfully working with nuts and bolts is to know the correct hierarchy of use. In other words, which of the available tools should be the first preference?

  • Number 1 Choice – Socket

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    The first choice in doing up (or undoing) a nut or a bolt should be a socket. If the nut or bolt needs to be torqued to a high value, a 6 point socket should be used. (In normal circumstances, either a 6 point or 12 point socket is fine.) The socket should be equipped with as short an extension bar as possible - preferably with none. (This to avoid applying a force that tries to lever the socket off the nut or bolt as it is being turned.) The socket can be turned by a ratchet handle, a sliding T-handle or even, for low torque values, a screwdriver-type handle.

    The only exception to picking a socket as the first choice is if there’s plenty of room and the nut or bolt is likely to be so tight that a lever needs to be added to the tool. In that case, use a ring spanner.

  • Number 2 Choice – Ring Spanner

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    The second choice of tool for doing-up or undoing a nut or a bolt should be a ring spanner. Where space above the nut or bolt will not allow a socket and ratchet handle to be used, a ring spanner is appropriate. Again, if the nut or bolt needs to be torqued to a high value, a 6 point ring spanner should be used.

  • Number 3 Choice – Open-Ended Spanner

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    Open-ended spanners are simply great tools... for rounding off nuts and bolts. Very few open-ended spanners have sufficient strength to undo nuts and bolts that have been adequately torqued. Similarly, very few open-ended spanners have sufficient strength to adequate torque-up nuts and bolts. Open-ended spanners should therefore only be used when there is inadequate space around the nut or bolt to permit either a socket or ring spanner to fit – and that’s a pretty unusual situation.

    However, open-ended spanners are very useful in undoing nuts and bolts that have been ‘cracked’ (ie the initial tightening torque undone) but which are sticky on the threads. For example, a Nyloc nut should be cracked with a socket or ring spanner and then, if it’s easier, can be undone completely with an open-ended spanner.

  • Number 4 Choice – Adjustable Wrench

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    An adjustable wrench or spanner is even more likely than an open-ended spanner to wreck the head of the nut or bolt. After all, it’s just an open-ended spanner with a built-in adjustment mechanism that allows the jaws to spring even further apart... Adjustable wrenches should never be normally used on nuts and bolts. Only in an emergency, where no suitably sized spanner or socket exists, should an adjustable wrench be used.

  • (Not the) Number 5 Choice – Pliers

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    Pliers should never be used to do-up or undo nuts and bolts. It’s as simple as that. The only reason I ever use pliers on a nut or a bolt is if it has already been rounded and it’s impossible to use a spanner or socket. If you ever see anyone using pliers on a nut or a bolt, they simply aren’t much of a workman (workperson – gender not implied).

    Tips and Tricks

  • Cracking’ Nuts or Bolts

  • Most nuts and bolts which have been torqued-up are pretty tight. Applying gradual force by a ring spanner or socket will often leave you frustrated and sore – the nut or bolt simply doesn’t want to ‘give’. The trick is to ‘crack’ the torque with a sudden, high force.

    On smaller buts and bolts (those on which you’d use an 8 or 10mm spanner), hitting the end of the spanner with your cupped hand will often crack the torque. On larger nuts and bolts, using a rubber mallet will perform the same trick.

    On really big bolts, like those used on suspension components, pushing hard with your foot will often crack them. Now kicking a spanner doesn’t sound very good workshop practice, but if you’re got the car securely on stands and you’re already under the car, you can apply with your foot a lot of force in a direction that won’t cause the spanner to be levered off.

  • Angled Extension Bars

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    Extension bars for socket sets are available with bevelled edges, allowing the extension bar to be out of line with the socket. These are sometimes called wobble extension bars and in some situations, they can be an absolute Godsend. These bars can be bought separately: they’re something you should have in your tool box.

  • Hi Torque Bolts/Nuts

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    If the bolt or nut that you’ve taken off was very highly torqued, think about why the manufacturer (or whoever previously did up the fitting!) made it so tight. If there is an important reason that it should be tight, consider applying a Loctite or equivalent locking compound. In many cases, using a locking compound means you won’t have to go ballistic on the torque (which saves potential thread stripping or nut rounding) and the fastener will be more secure than before.

  • Accurate Torquing

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    Anything involving bearings (plain, roller, needle), important gaskets (eg head gasket) or castellated nuts (ie a split pin goes through the end) should have the bolts torqued as described in a workshop manual. That might mean applying a certain peak torque (as measured by a torque wrench) or by a certain angle of rotation.

  • Direction of Rotation

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    Pretty well anyone who has even picked up a spanner knows that you turn it clockwise to do the fastener up and anti-clockwise to undo it. But two points. Firstly, these directions are reversed if the fastener is upside-down (and only the other day I saw a mechanic of 30 years’ experience get this wrong!), and this convention applies only to right-hand threads. Some special threads are backwards - eg on specific gas cylinders, some fittings associated with rotating shafts and some tie-rod ends.

  • Multiple Fasteners

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    If the object you’re working on has in held in place with multiple fasteners, never tighten one fastener to full torque before doing up the rest. Instead, torque them up evenly, working your way back and forth across the object. This applies to wheel nuts, cylinder head bolts, tappet cover bolts – anywhere there’re multiple fasteners used to hold something in place. And the reason? You want the object to ‘bed down’ evenly, not end up cocked on one side.

  • Nipping Up”

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    In most cases, fasteners don’t need to be mega-tight. It’s one of the most common mistakes a beginner makes - assuming that every fastener has to be as tight as they can make it. In fact, most fasteners can be “nipped up”. This means tightening the fastener to the point where it starts to resist tightening, and then applying a relatively small but sudden shock to the end of the spanner or socket handle. Sump plugs, for example, should be nipped up – tight enough that they’ll never fall out but not nearly tight enough that the thread will be stripped. On the other hand, suspension and brake nuts and bolts should be quite a lot tighter than being just nipped up.

    Conclusion

    If a long time ago someone had told me about the concepts of 6 point and 12 point sockets, the hierarchy of tools to use when doing-up nuts and bolts, cracking nuts, and the idea of nipping up, I’d have spent a lot more time over the years enjoying my work on cars – rather than staring sullenly at rounded-off bolts...

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