Good mechanical skills depend upon a good attitude and the right approach. You have to recognise the importance of every part you handle, no matter how insignificant it might seem.
When it comes to seized nuts, bolts, and screws, most home mechanics quickly become frustrated and start forcing the issue before they’ve really thought about the implications of the problem. That usually makes the problem worse, which naturally leads to a loss of temper, which generally destroys the fastener – be it a nut, screw or whatever – which in turn ruins the job.
The first thing to do before removing any fastener is to make sure you’ve got the CORRECT tool. Sounds simple enough, but many home mechanics get it wrong time and time again. So don’t even think about using, say, a Whitworth spanner on a metric nut, or vice versa. Don’t use ANY spanner on any nut or bolt that wasn’t designed for it. Even if the spanner fits and works, it might well damage the fastener, thereby giving you problems the next time around.
Never use the wrong size screwdriver either. Never use the wrong socket, Allen key or any other tool. Only RIGHT is right. Everything else is WRONG – although you might get away with it nine times out of ten. But that tenth time is where it all goes pear-shaped, and suddenly you’ve wrecked a valuable component, and maybe injured yourself too. So check the fit of the tool. Then check it again.
Given that you’ve now got the right tool, use gentle pressure to see if the fastener is going to give you problems. Typical warning signs of impending problems are graunched nuts, or damaged screw heads or corrosion. Also, nuts and bolts that have been subject to heavy torsional (twisting) forces often cause major problems (such as wheel nuts). Nuts and bolts and screws that have been subjected to repeated heating and cooling (exhaust clamp bolts, for instance) are also likely to give you trouble and are prone to shearing. Remember too that a bolt that suddenly shears might lead to other damage on the bike. Or on yourself.
If you suspect an imminent problem, get out the freeing oil. Use WD40, Plus Gas, or whatever brand you feel is best (and the internet is full of heated argument advocating one brand over another). Even ordinary diesel oil is a pretty good penetrant. Ditto for 3-in-1 oil. But as with all oils, try and keep it off your skin.
Now liberally coat the offending fastener in oil. If you can leave it overnight, so much the better. If not, leave as much time as you can before tackling the job – and that means never less than 10-15 minutes. Time enough for a cuppa. Then come back and apply some more freeing oil.
Next, check that there aren’t any lock washers in place, or any other mechanical device designed to stop the bolt or screw from coming loose. Check too that there aren’t any burrs or other obstruction.
If you’re happy so far, it’s time to try a little more force, so reach for the RIGHT tool, which means a tight-fitting tool. Remind yourself once again of the importance of EACH fastener. Don’t mentally dismiss any of them as minor obstacles to be overcome. Each nut, bolt or screw can stop you completing the job, and might cause you to lose your temper when it suddenly becomes unusable. So go carefully.
If you can “shock” the fastener, that can help. You can use a centre punch for screws (giving it a short, sharp, central whack with a ballpein hammer). For bolts, a sharp whack on the end often suffices (either before you apply force with a spanner, or while you’re applying force). For nuts, you can try tapping around the flats – but take care not to damage or compress the threads. The idea is to jolt the metal, which will have built up tension. If you can jolt it while it’s covered in freeing oil, the oil will often find its way deeper into the offending threads and help release the tension. But it needs time to work. So try and plan ahead and set to work with the freeing oil a week or two before you start the restoration job.
If oil and carefully applied force doesn’t do it, stop and try some heat. Avoid a naked flame. Use a heat gun or even a hair dryer if that’s all you’ve got. Watch the paintwork, and keep the heat away from petrol. Consider removing the entire assembly so that you can work on it on a bench where you might be more comfortable – and where you’ll have a vice to hold it securely.
If heat doesn’t do it, consider squirting the component liberally with freeing oil, then wrapping the component in plastic film and freezing overnight (where possible). Remember; you need to release the compressive forces in the thread. Within reason, anything you can do to change the metal-to-metal interaction can only help.
Also, consider these suggestions before you attempt to tackle the fastener.
1. Use a Metrinch spanner. These have a four-point grip as opposed to a conventional two-point grip, and they on grip the “flats” of a nut or bolt rather than the corners thereby becoming tighter as you apply force. If you don’t have a set of these, now’s the time to get some before you continue. Good tools will repay themselves time and time again.
2. If a screw head is damaged, can you use a needle file to improve the slot? You might get only one chance at this before the fastener is damaged. So go easy.
3. If a nut or bolt is damaged beyond repair, can you weld a torque bar or secondary nut to it?
4. Is the bolt or screw likely to shear through corrosion, wear or age? If so, consider the implications of this before continuing.
5. If the bolt shears, will that stop you from removing the assembly? Or will it help? In other words, consider deliberately breaking the bolt and replacing it – but not if the bolt is seized into a casting, unless you plan to have it spark-eroded out (see below).
6. Can you tap on head of the screw or bolt as you unscrew?
7. Better still, do you have an impact driver? Or can you get one?
8. Do you have a nut splitter? These are cheap and effective tools, but are not always easy to apply when the nut is in a confined space.
9. If you’re working on an Allen screw, do you have an Allen socket that will allow you to apply torsional force as you tap/strike the end of the screw? Once again, an impact driver would be better.
10. Can you get an air tool on the fastener? Or an electric impact driver? Often, these will work instantly where spanners and ordinary sockets will get you nowhere.
11. Can you get the component loosened elsewhere?
12. Can you drill out the screw or bolt?
13. Consider using an Easy Out for damaged screws. These drill into the screw on a reverse thread. They’re not always effective, but are a cheap and useful tool to have in your arsenal.
14. Consider using a stud extractor where applicable. But careful. A seized stud often shears. So think about the implications of this.
15. If you get any movement at all, try some more freeing oil before you apply more force.
If you try all these methods and fail, you might consider grinding off the nut or bolt head with an angle grinder or Dremel. And if that fails, you’ll need to talk to an engineering shop that specialises in spark erosion. This directs an electrical spark at the offending fastener. It’s often surprisingly quick and effective. As with everything, prices vary. But if you’re working on an expensive, fragile or rare component, you might not have much choice.
Above all else, NEVER start on a screw or a bolt unless and until you’ve considered all the implications of the problems that you’re likely to face. Just stop. Back off. Drink some tea or coffee. Research if you’re still unsure. And above all else change your attitude.
Ultimately, it’s all solvable, so don’t panic. Just remind yourself that every fastener is a major problem in itself and needs to be treated with respect and caution. Anyone can remove a new nut and bolt. What makes a mechanic good or bad is the attention he or she gives to problem fasteners.