Removing stuck fasteners
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*No matter what technique is used, when removing stuck fasteners, you need to pay attention to what is turning and what is not. | *No matter what technique is used, when removing stuck fasteners, you need to pay attention to what is turning and what is not. | ||
*There is no general consensus as to whether steady or intermittent pressure is best for removing stuck fasteners. | *There is no general consensus as to whether steady or intermittent pressure is best for removing stuck fasteners. | ||
| − | *Keep in mind that fastening hardware stuck together by corrosion is stuck because the corrosion has expanded and tightly bound the fastener. This means a really stuck bolt will not allow penetrating oils in to do any good. | + | *Keep in mind that fastening hardware stuck together by corrosion is stuck because the corrosion has expanded and tightly bound the fastener. In theory, there should be nothing to stop you finger-tightening the bolt until it's snug or easily loosening a bolt once it has been fastened snggly. In practise, it's often quite hard to turn some bolts or loosen other bolts, even when they are slack. The reason for this is that dirt gets stuck in the bolt threads, and it gets trapped when you start tightening the bolt making it harder to turn. This is a warning sign -- if you can't finger tighten a bolt until it's snug then there is something wrong. If you are trying to put a bolt in, then take it out and clean the threads. If you are trying to loosen/remove a stuck bolt, see if you can access the end of the bolt (opposite end of the bolt head). Put a little grease on the threads before you try again. It's a bad, bad idea to get out spanners early to carry on trying to tighten a bolt that isn't turning smoothly. Even if you get it tightened, that dirt is still in the threads, and it's quite likely that it'll jam the threads when you try to next remove the bolt. |
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| + | Dirt-jammed threads are a pain when you're putting a bolt in. They're much worse when you're trying to remove a bolt. Imagine what happens if the thread is jammed at the far end of a bolt which you're trying to remove. You turn the bolt head, so the top of the bolt is getting pulled out. However, the bottom of the bolt is jammed in place. In this situation, it's quite likely that the two halves of the bolt will seek a divorce. Suddenly, the bolt becomes very easy to turn, because the top half has broken off and isn't under tension any more. The bottom half of the thread is stuck inside some bit of your bike. Good luck getting it out! | ||
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| + | Remember: bolts should turn smoothly. If they don't, there is something wrong.This means a really stuck bolt will not allow penetrating oils in to do any good. | ||
*There are two effective means to break the friction that corrosion has caused. One is through mechanical movement, a proper good whack with a hammer. The other is through differential heating. Making one part expand more than the other. | *There are two effective means to break the friction that corrosion has caused. One is through mechanical movement, a proper good whack with a hammer. The other is through differential heating. Making one part expand more than the other. | ||
*With heating, bear in mind axles and other important structures may lose their strength if they are heated much above 300 degrees. If you have the oil and grease starting to smoke, then you are in the 300-degree range. | *With heating, bear in mind axles and other important structures may lose their strength if they are heated much above 300 degrees. If you have the oil and grease starting to smoke, then you are in the 300-degree range. | ||
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