What’s going on?
The first thing to do is to understand at least a little bit about the cause of the rusty fixing mess. Basically, the cause of bolt sagging is one thing: rust. It occurs wherever there is a galvanic pairing – the proximity of two different metals. Different is not necessarily steel and aluminum, even two identical alloys will rust at the point of contact due to a slight difference in proportions. But that is not the main thing.
The main thing is that rust in terms of chemistry is hydrated iron oxide. It arises from the oxidation of iron under the influence of oxygen in the presence of water. There is a lot of iron in the fastener, there is oxygen in the air, and water is pouring from the sky at all times of the year (though sometimes in the form of snow or fog). In general, all the necessary conditions for corrosion are always there. And so this process is inevitable, although it can be suspended (about this I will tell a little bit below).
With threaded connections, the same thing happens: hydrated iron oxide is formed, which greatly increases the friction between the coils of the threaded connection. It’s obscenely simple, and sometimes it’s maddeningly unpleasant. It’s especially unpleasant when connections that are exposed to high temperatures (such as fasteners in the exhaust system) rust. There is often nothing to do here, and it is necessary to resort to the most radical means – grinder. But before it makes sense to try more humane ways. They can be divided into three groups: physical, chemical and mechanical. Let’s start with the last one.
Gently but firmly.
The easiest way is to tap a hardened nut with a hammer. Exactly tap, not hammer with a sledgehammer with all your might – you can finally kill the thread. Small shifts can destroy the rust layer and make it much easier to break the connection. After tapping you can once again take the key.
Speaking of keys. Trying to undo a stuck nut with a wrench is not the brightest idea. Especially if the head is also rusty or dirty. Powerful and smart men use either sockets or ring wrenches for this purpose. And before that, they try to clean the head well. If it is dirty, the head of the right size simply will not fit, and a larger one will lick the facets if you try hard enough. All of them.
And a little bit of the obvious: for a wrench, you have to find an extension (a.k.a. amplifier). Usually it is just a tube that can be put on the handle to increase the leverage. Often helps, but unfortunately, the use of such an extension is sometimes impossible due to space constraints.
Another mechanical method is to tap the key. Sharp and short impacts (taps) can tear off the rust on the threads, and it is almost a victory. It makes sense to tap not only in the unscrewing direction, but also in the opposite direction. The main thing is to move it, and the impact in the opposite direction in this case can be effective.
If the edges are still torn, you have to remember the good old garage method used by our fathers and grandfathers – put a chisel to the nut and tap it with a hammer. If you make a quality notches and try to tear the nut for unscrewing, you can achieve some success. It does not always work, but often.
Fuel oil, kerosene, liquid wrench
Chemical methods, of course, will not unscrew the nut, and the last word will still be a wrench or a head with a screwdriver. But they are very helpful for these glands to do their job. The main task of chemistry is to loosen the rust on the thread. Of course, the first assistant is a liquid wrench. And in the case of a stuck connection, the most important property of the wrench will be its penetrating ability. It is important to remember only that the compound must be used correctly. That is in advance. Generously pour the connection and wait. It is better to wait 20-30 minutes, before the well boiled threads can be unscrewed – the liquid must enter the threads to the maximum and at least slightly dissolve the rust.
What to do if there is no store within walking distance, and the liquid wrench is needed? Again we have to remember the experience of the older generation. As I said before, the main property of a wrench is penetration. And many more affordable liquids have it. In the extreme case, even gasoline will do, but it is better to use kerosene or diesel fuel. And also work and antifreeze, and even brake fluid. Soak a rag with it, put it on the connection and wait. We wait a long time, sometimes an hour or two. Sometimes we soak for 24 hours. And then – hit with a hammer, twist with a head with an extension cord, knock on the chisel. In general, as the soul wants or what will be the need.
Sometimes acid is used instead of these liquids. Usually they advise hydrochloric or sulfuric acid. You must be very careful when working with acid. Do not pour it on a rag – the acid will simply corrode the cloth. You will have to think for yourself how to pour it over the nut. In principle, the result can be good, but “Vedeshka” is still easier, safer and more reliable.
By the way, some comrades are convinced that a good result can be achieved with Coca-Cola. According to them, it has orthophosphoric acid, which is quite good to eat the rust. Frankly speaking, you can pour Coke on a rusty nut only in a fit of despair. It is of little use, but the appearance of action is somehow soothing.
Burn, burn clearly
And now let’s call physics to the rescue. As you have understood, we are talking about the expansion of bodies when heated. The easiest way is to red-hot the nut with a burner or a blowtorch. In an extreme case, you can try to heat the joint with a construction hair dryer, but this method of heating is not very effective.
Theoretically, when heated, the nut will expand, and then it will be easier to roll it. In practice this is how it is. Another thing is that if you do not work in the service (and you hardly work there, if you read this), you hardly have a gas torch at hand. So this method is conventionally available and not suitable for everyone. This is not very good, because it is very effective.
By the way, if you do not have a burner, but you have a transformer, you can try to heat the connection by shorting with high current at low voltage. But such experiments can only be done with experience and proper knowledge.
The great disadvantage of heating is the flammability of the process. Where there is oil or gasoline, using an open fire should be even more careful than sleeping with another man’s wife. That’s a pity, because the method is effective.
If it’s a misfire.
So, it’s time for the heavy artillery. If all the nut’s relatives on the maternal line have long been spinning in their coffins at the speed of a fan, there is nothing left but to pull out the drill or a bolt cutter into God’s light.
The drill is good in itself, but besides it you need an extractor, which you then have to screw into the hole drilled in the bolt. It is necessary to take the drill so that the extractor could be screwed into the hole afterwards. And it is necessary to drill strictly along the axis of the bolt. It is difficult to do without experience. Before you pick up the drill, you need to ask yourself an honest question: can I drill well enough not to screw up anything but the bolt? If the bolt is screwed into an important part, you need to think very carefully. Preferably several times.
The lathe is quite another matter. It is easier to work with it (if you are not trying to cut a wedding ring from a finger with a lathe weighing six kilograms, power under 3 000 W and with a disk of 180 mm), it is easier to find it, to screw up an important part is not so scary. In a pinch, buy a grinder is not too expensive (can be found in the range of 1,500 rubles), and normal disks for it are much cheaper than good drills and extractors. Well, a good cutting disc will cost no more than 30 rubles, and it’s even cheaper than Vedeshka. And most importantly, the cutter – this is almost the only way to unscrew the threaded connections where corrosion is exacerbated by high temperatures. For example, in the exhaust system. And the second hit of the season is the camber bolts of the rear multilever. It is necessary to cut them almost always. And it is senseless to suffer with them: anyway these bolts are replaced for new ones. So, why to suffer unnecessarily?
Speaking of cut-off wheels. Let’s take a commercial break. Judging by the experience of some service stations we can safely recommend NovoAbrasive products. Their discs are good, but it is very important to choose exactly the disc you need – for cutting and metal. About a stone wheel I will not say anything (and NovoAbrasive also have them), but to cut metal with a grinding wheel – it is not very smart. Although, of course, grinding with it is possible and even sometimes necessary. But it is better to destroy a nut with a cutting wheel.
Well, a few kind words about NovoAbrasive: grinding wheels are made there on the Italian equipment, so the quality is not at all worse than the European. And they are cheaper, which is very good.
In addition, the wheels are tested not only for performance, but also for safety, including the breaking. For the sake of interest, you can google videos and see what happens when a disk breaks in a grinder. These are very interesting videos.
In general, it’s all fine, but in any case, when working with a grinder you need to observe basic safety standards. Protective goggles, gloves and… no alcohol with men in the garage. Yes, yes, it’s sad for me, but my fingers are more expensive.
Going the other way
I’m sure that after prayers and curses about rusty threads the question will arise: is it possible to avoid it somehow? Unfortunately, it cannot be avoided at all. But the situation is not quite a dead end.
Those bolts and studs, which have to be unscrewed more or less regularly, should be treated with grease every time. I will not be original: in most cases, ordinary copper grease will save from sticking. At least the nuts (studs) of wheels and threaded joints of chassis parts are easy to grease with it. But keep in mind, that it is harmful to rubber parts, therefore it is not recommended to fill it into dust collectors.
Well, and if anything, call your “bolgarin’s wife”. As in a fight there is no method against a crowbar, so in repair no one has ever resisted a bolt cutter. Just work carefully: you can always buy a new bolt, but you can’t buy a new hand yet. Even if it is crooked and sticking out of the wrong place.