Torque wrench with my own hands at home
I decided to make my own post about this topic. I used NissanObiWan materials and made some modifications for convenience.
So, let’s go. Wrench assembled on the basis of standard tool kit (I have Ombra) 1/2″ section Naturally, you can assemble a wrench on the basis of any available tool.
The necessary accessories: – Sliding screwdriver assembled with 2 х extension cords 1/2″ 125mm and 250mm – Hand scales – Head 1/2″ any size (for fixation of scales) – Clamp suitable size (for fixation of scales) – Screwdriver (for fixation of clamp) – Measuring tape (for measuring the total length of the assembled wrench) – Table for calculating the tightening torque of screw connections download Table allows you to determine whether the tightening torque of screw connections in newton per meter (N/m) and the applied force in kilograms (kg) according to the scales.
In car service manuals, you will often find tables indicating the tightening torque for fasteners.
It is especially important to observe the value on parts such as the intake manifold, cylinder heads, suspension joints. Masters of service stations use special devices: torque wrenches. It is a costly element: if it is used occasionally, it is not reasonable to buy it. Therefore, many car owners, servicing cars on their own, make a torque wrench with their own hands.
Completely free to make a tool will not work: at least a factory wrench is needed, as well as a device that fixes the torque.
What is a torque wrench for?
A certain torque on the mating parts is necessary for the even fit of the planes. Also, if a gasket is installed along the contour, uneven bolting torque can ruin it.
A torque wrench allows you to tighten bolts to within a hundredth of a millimeter. In addition, it is often necessary to torque the bearing seat with high accuracy.
The manufacturer calculates the torque values based on the type of material and design features of the assembly. When the car is built in the factory, all fasteners are tightened according to specifications: this work is usually performed by assembly robots.
And when servicing, repairing, replacing parts – the necessary force is provided by a hand tool: a torque wrench.
Its main advantage is the ability to work in a wide range of settings. You just set the limit of operation with your hands, or visually control the arrow of the torque meter.
That is, a universal torque wrench does not allow for equally accurate tightening of nuts with a force of 2 Nm and 100 Nm.
Tool manufacturers produce torque wrenches in several ranges:
- The most popular “size”: 40 – 210 N.m. It allows you to perform most of the repair work on the chassis of the car;
- Precision torque wrench (2 Nm to 50 Nm) for engine repair and maintenance. Carburetor adjustment, spark plug tightening, crankshaft and connecting rod assembly. Work on replacement of intake or exhaust systems, also done with a small range torque wrench;
- Tightening torque of 200 Nm and more is designed for heavy-duty applications. In the case of automobiles, perhaps only the hub nuts.
How is a torque wrench for automobiles constructed?
There are two design solutions: torque limitation, and visual control of the process. Let’s consider each of them in detail.
The so-called ratchet
Externally, it does not differ much from the usual lever with a ratchet for sockets. In fact, that’s what it is. It’s just a ratchet mechanism with adjustable actuation force that has turned an ordinary handle into a torque wrench. The secret is in the ratchet design. It allows the pinion to spin in either direction.
In the return direction, when you pull the handle back for the next turn of the head, the force is minimal. But in the operating direction, where force is applied, the ratchet tooth slips off the pinion when it reaches the set point.
In the handle of the shank, there is a rotating nozzle. It adjusts the ratchet spring tension.
How does the system work?
When the set torque value is reached, the ratchet pinion starts to slip. The handle rotates with a characteristic sound, and the nut does not tighten.
The ratchet torque wrench is semi-automatic. It makes it possible to tighten the nuts without fear of overtightening.
Measuring scale
A torque wrench does not have a torque-limiting mechanism, but a dial or digital dynamometer is attached to the swivel mechanism. When force is applied to the handle, the arrow will deflect and you can record the amount of force applied. The principle is quite simple, the arrow stays in a constant position in relation to the wrench head, and the crank bends like a spring torsion. As a result, the scale moves with respect to the tip of the hand in proportion to the applied force.
The disadvantage of this model is that there is no automatic limiter. You simply control the force that is applied to the handle. This allows you to make a more accurate measurement (unlike a ratchet, which works discretely), but there is a chance of mechanical error in dosing the force.
A homemade ratchet-based torque wrench is difficult to make, the technology requires metalworking machines and precision calibration. But a tool with a dynamometer is quite feasible for the home craftsman.
Variants of homemade torque wrenches
To begin with, let’s remember the school course of physics. The measurement of torque is made in newtons per meter. Without going into formulas, practically it means: 10 N.m. – is equal to a force of 1 kg applied to a lever one meter long.
That is, if you measure from the center of the head of a ring spanner 1 meter, and fix a dynamometer at this point, you can measure with a high degree of accuracy the torque of tightening a nut.
This method is not new: owners of VAZ and UAZ cars, when repairing the reducer of the rear axle, used the methodology developed back in the Soviet times.
The shank nut, which compressed the tapered bearing shells, was tightened with a strictly dosed torque. The torque was controlled with a home-made dynamometer, and in its absence, a “precise” measuring device was made from a steeple. In fact, this is the prototype of homemade torque wrench. Only as a lever is used the flange of the half-axle.
How to make a torque wrench with their own hands to make it easy to use?
A meter handle wrench is not the most practical option. Let’s use the rule of calculating the force depending on the length of the lever. There is no point in studying formulas, the values are calculated in proportions.
The shorter the lever, the more force should be applied (while maintaining the value of the torque):
- lever 1 m, torque 10 N.m., force 1 kg;
- lever 0.5 m, torque 10 N.m, force 2 kg;
- lever 33 cm (already comfortable to work), torque 10 N.m., effort 3 kg.
To make it we will need:
- a handle for working with sockets under the square (for greater versatility – with an extension).
- clamp for fixation of force measurement point.
- measuring device: you can use ordinary scales of the “changeless” or “cantor” type. The optimal measuring range is from 100 grams to 50 kg.
Having measured from the center of rotation the necessary length, fix the clamp on the lever. The device is ready in 15 minutes. It is possible to mark several points of the clamp installation, depending on the measured torque.
If you do not want to make your own hands a separate tool – use a standard set of wrenches (one side of the horn, the other – a ring spanner). The principle of action is the same exactly. For each wrench (since they are different lengths), in advance make a table of calculation. You can use a ready-made application for your smartphone:
Enter the data obtained (lever length, cantor readings), and see the finished result in newtons per meter.
Tightening the bolt with a homemade torque wrench – video
Conclusion: Having in hand a changer worth 300 – 500 rubles (it is present in almost every home), you can save on the purchase of a manufactured torque wrench: the price is about 2000 – 3000 rubles.
Time to read: 6 minutes
Every experienced car enthusiast or professional technician knows that many parts in the car require a special effort when tightening. For example, if insufficient torque is transmitted to the nut to tighten it fully, it can become loose when moving, and, on the contrary, overtightening the fastener can ensure deformation of the part.
That is why a torque wrench is one of the most important parts of every technician’s tool kit. However, it is quite expensive, and some craftsmen make the tool with their own hands.
Torque wrench
A torque wrench with their own hands
The torque wrench is a tool for the masters of service stations, designed primarily to ensure an even application of the load on a particular fastening element, it provides an even tightening of each bolt or nut.
The electronic or pointer scale on this product allows you to tighten components to within tenths or even hundredths of a mm.
At a closer look, the product is an ordinary lever with a ratchet on the end, which does not allow the technician to overtighten and simply cranks it idly, according to the pre-set parameters on the dynamometer.
The dynamometer is a simple spring mechanism that, when tensioned, causes the hand on the dial to deflect from the zero mark to the limit value set by the user.
At the base of the lever is a rotating limiter, with which the master sets the exact value of the required limit force before starting work.
Parts for the wrench with your own hands
Thus, with some home appliances on hand, as well as a little ingenuity and knowledge of elementary physics, any man can make a similar wrench without leaving home or garage, and the result will not differ much from the readings of the device purchased in the store.
Torque wrench without a scale: what to replace it with
To make a wrench easy to use and to be able to properly operate, the user needs to know a simple formula from school physics, namely that the torque of 10 N*m is the product of the weight of 1 kg, applied at a distance of one meter from the point. So, it is not difficult to guess that a lever of 0.5 m reaches this value with a force of 2 kg, 0.2 m – 5 kg, etc.
Based on these calculations, the craftsman should purchase or find the following parts to make the tool:
- The handle, which has square-shaped tips, and the length of the product should correspond to the above calculations in order to achieve a more accurate result.
- If it is not possible to cut the lever, it is always possible to mark it with a marker or simply put on a tight clamp, which will be the starting point for applying the load to the fastener.
- Instead of a dynamometer you can take a regular high-precision bezmen – scales that show the load in grams, depending on the strength of the tension. Experts advise to buy this instrument with a scale value of at least 100 grams and a limit of weighing up to 50 kilograms.
Professional tips for making a wrench
From the first time the tool may not work, and the measurement will not be correct. However, any experienced craftsman can give some detailed tips, following which every beginner will achieve the desired result.
In the absence of a lever or materials for it, you can use an ordinary wrench with a horn grip on one side and a ring spanner on the opposite side. However, the length-to-torque ratio should be calculated more carefully here, as the arm size will probably be a fractional number.
For the best fixation of the changer to the lever, you should be especially careful about where you mount it. The best option is a carefully drilled through hole, exactly where the load is applied, and the instrument will never slip off the handle.
Working with a homemade torque wrench
Depending on the tension required, the craftsman may have several changers at once with different weighing limits, each of which should have its own table of load vs. arm and torque.
Since all the effort in determining the degree of tightening is applied only to the scales, a comfortable grip on the handle must be ensured, since 20-30 kg with a poor grip will not allow comfortable operation of the instrument.
How to measure the tightness
To correctly measure the tightening with a homemade device, you need to follow a few simple rules:
- Assemble the device and make it work – attach the changer to the handle, set it to zero, if possible – set the weighing limit with an alarm, and finally – put the necessary attachment on the operating device or initially choose a spanner of suitable size.
- Put the spanner on the nut or bolt. The device will only show the exact value if the connection to the fastener is made directly through the lever, and if one or more adapters and extensions are involved, there may be an error of up to 5-8% in giving the result.
- Carefully pull the bezzer so that its position is strictly perpendicular to the axis of the lever and the load indicator is not distorted by decomposing into vectors.
- If normal force has been achieved, the instrument will confirm this with the measurement and the nut will not move. If, however, the tightening was not sufficient, the fastener will turn around its axis before reaching the required torque.
Basic mistakes when making a wrench
Any high-precision tool cannot be made at all without mistakes, since the craftsman has no exact designs or drawings at hand, and all this can lead to incorrect measurements and breakdown of car parts later on. However, many professionals have answers on this point as well, offering car owners a number of recommendations in order to minimize errors and inaccuracies, in particular:
- As a lever you should not take a soft metal, which can easily bend when pressing, because the force applied to the changeless without observing orthogonality will not give the desired result, and the purpose of the device will be completely lost.
- You should not choose a cheap changer, because the accuracy of its measurements is very questionable, and the spring quickly stretches and fails. So, as of December 2018, the cost of scales should be in the neighborhood of 400-500.0 rubles. This is not much compared to the price of the torque wrench itself – about 3-4 thousand rubles, and the low-quality component is better to change immediately.
- When attaching the nozzle to the nut, you need to take into account that it must be perpendicular to the axis of the lever, and otherwise the measurement will not work.
- Most of the changeless changers have only an informational function and do not limit the actions of the craftsman in any way, who can easily get distracted and overtighten the bolt without paying attention to the scale reading.
Therefore, when using a homemade one, the foreman is much more responsible because the device may not have the automatic force relief features of a commercial counterpart.
Service Station
A homemade device is best used to monitor bolt tension when in doubt. If it is necessary to control the tightening on any complex component part, the motorist should still go to the service station for diagnosis and repair, do not replace important components in your garage, because unauthorized intervention can cost much more than the money saved on the key.
Garage man’s tools: homemade keys and nuts from rocket KB
In my work, tools and equipment are an absolute necessity, like air or water. Every mechanic has a different approach to this. Young people, of course, are now buying modern kits at once. But since I first disassembled a machine at the end of the era of “developed socialism” and I still use some things from that time, I have a complete eclectic mix – everything is different, partly haphazard, but at the same time for me as practical and convenient as possible. Yes, I do not have anything in the “expensive-rich” style. A tool is an ordinary consumable, which wears, breaks, gets lost and is sometimes forgotten in clients’ cars. That’s why I have never had and never will have a Snap On-type wrench with a lifetime warranty and a price to match. Everything in the shop is set up to make money at minimal cost. Like the old joke about “check or go” – I only have “go”, but no “checkers” at all 
Yes, it’s not an ideal repair shop, but it suits me and, more importantly, my customers.
I will start with the main thing – the elevator. It lets me not only work faster and better but it also keeps me healthy. Many garage attendants work on a pit or a jack, and as a result, they inevitably get serious back and joint problems. But I am not acquainted with it yet, and it is due to work on an elevator. So what is it?
It’s not young, it was made more than 20 years ago in then brotherly Poland. In those years these elevators were quite widespread in our city, in particular similar ones were used in the local service station “AvtoVAZ”, the only one at that time. Its main advantage – space saving, which is important for garage conditions, and very reasonable price. The disadvantages are much more – it is very slow, noisy, and its lifting capacity is only 1500 kg. In addition, it can only lift cars with a rigid and long enough straight sill, and the width of the car is strictly limited – at most as Chevrolet Cruze or Mazda3. But it’s enough for most of my regular customers’ cars, and that’s all that matters to me.
The power nut is made of bronze, with a steel safety nut underneath. The “native” nut lasted ten years, but the custom-made ones lasted three or four years at best. And the nut made at the local rocket design bureau, where I used to work, lasted the least. I wonder why rockets sometimes fall down… However, this is not the point. By the way, it costs 4000-5000 rubles per nut, including metal.
The safety of this elevator… Once in another workshop I had to see how one of the nuts on a two-post elevator cut off while the car was being lifted. The mechanic who was working on the elevator didn’t notice that the bearing nut had already been worn out long time ago and the lifting of cars was done only due to the safety nut. And when it was worn out, one half of the elevator fell down with a rattle, as soon as the wheels of the lifted car came off the floor. But the second strut of the elevator remained to hold the car, and the car was strongly distorted. Fortunately, neither the equipment nor the people were hurt.
On a one-post elevator, when the load-bearing power nut is worn out, the whole frame sharply settles on the safety nut, while the car is hanging level, as it was, and I just need to lower the elevator. Of course, this elevator is not eternal, and in case of a serious break it will have to be replaced, but for now it works. And the support under it is just to be on the safe side.
Together with the elevator, you often use the sliding stand – to push up the suspension when tightening the silent blocks, to support the engine when removing the gearbox.
And now about the wrenches. There are not just a lot of them in the workshop, but a lot Some were bought, some were given as gifts, some got by chance. No brands, mainly “Delo Tehniki”, “King Tony”, “Jonnesway” and the like. Here are the usual sleeve horns…
With ratchets (nice pampering, but short-lived)…
Curved sleeves and with them for the company of non-standard sizes…
And a backup set of different….
And separately for tube nuts…
Why so many wrenches? Well, you have to have a couple of all common sizes, because you can’t always get to the bolt and nut with sockets and screwdrivers. Curved sockets – at least one per size, too, just in case. Plus not the most standard sizes – for 16, 18, 21, you can’t do without them nowadays. I remember how a friend in the early 90’s disassembled gearbox on the Volvo 340 and swore that they needed wrenches and sockets for 15, but where to get them then. And how I tried to unscrew 80’s Audi back in 1993, with self-made “sprockets”… How young we were… but never mind
Yeah, about those “sprockets”. Over a couple of decades several of these kits have been used, eventually all the surviving nozzle-inserts have been consolidated into one box. They are complemented harmoniously by the corresponding heads.
Now the heads. There are as many of them as there are socket wrenches. The logic here is the same – there must be two heads of each used size. Ratchets, wrenches, wrenches – of course.
It is desirable to have both hex and “star” sockets in the same size.
There are also power heads, big screwdriver and special tools in the form of heads welded to a crowbar
Separately there are extended heads.
Some tools can be called historical artifacts, if not rarities These tubular wrenches (the most convenient thing!) have the price of 1 rub. 20 kop. and 80 kop.
Yes, there was a time when you could buy something for one ruble, and the prices were so stable that you could engrave them directly on the item. If you tell our young people about this now, they wouldn’t believe it.
I still gladly use a set of heads that were made in Chernigov, Ukraine, during Soviet times. I wonder if the factory is still in operation.
And this wrench was also once made in a country that has long since ceased to exist…
Of the three torque wrenches, two are also from those long ago.
Well, let’s get back to the present and go over small-scale mechanization and electrification. Here is one of the main helpers at work. Axe-sharpening knives – that’s for sure, but not only.
First, I don’t like standard internal chamfers on the heads and make sure all heads and ring wrenches are torqued, so they can cling more reliably to the bolt-nuts. Secondly, sometimes I have to hastily grind some heads on the outside as well. Besides, horn wrenches sometimes need some work as well. This 32″ wrench was sharpened for timing belt tensioner roller of the very first 8″ cars long ago.
This one is “24” machined for holding the Opel camshafts of the “Ecotec” engines.
Sometimes it is necessary to chamfer the head for a heavy-duty open-end wrench in order to use the head for disassembly of a suspension strut, or to work in tight places, when the ring spanner comes off.
And if you grind a little bit the edge of the old piston pin from “Zhiguli” you will get an excellent knockout for the crossbody cups.
Well, no comment here.
Although I work on a hoist, there are several mechanical jacks in the household. In my opinion, they are more reliable than the hydraulic ones, although, perhaps, it is just a habit.
Now special tools. It seems to be a lot of them, but always not enough. Here are countersinks and reamers for repair of heads of blocks. Well, why everybody calls them “countersinks”.
Since we are talking about repair of cylinder heads, how to be without dipsticks, extractors of valve seals, struts and the like.
The shims are remade for different sizes of valve disks.
Since I am making motors, I can not do without compressometer and oil pressure gauge with adapters for different engines.
Indispensable thing when repairing engines – a compressor. To blow out the remains of swarf after the lathe work, to blow out dirty spark plug wells before replacing the plugs, etc. Got it when writing off old equipment in a dental clinic, made in Israel.
No less useful thing for the motorist is this tray. I bought it from a conscientious alcoholic, who walked past the shops and offered it to all, because just give it to him for scrap metal, he was sorry, the thing is a useful thing.
The dent in the side of the pallet appeared when it saved my foot from a customer’s car unexpectedly hitting me. Standing vertically against the wall, the tray bravely took the brunt of the blow. But that is another story.
It’s very convenient to wash parts in it, if necessary it can be put under any car to drain the antifreeze. And it’s very easy to clean.
There are mandrels for centering clutch discs in different sizes, but nevertheless you often have to use universal one in form of a bolt with wrapped electrical tape
And this is a mandrel for fixation of pinion-satellites while removing gearboxes of front-drive VAZ cars. Yes, you can do it with rolled up newspaper, but not necessarily
This old VAZ clutch disc with welded strong nut, I use it for fixation of the primary shaft while disassembling the gearbox.
And this tool is not recognized by the modern driver, let alone a mechanic
This is a tool for sharpening the edges of these cylindrical tubes. What are they for?
All together it is a kit for punching holes of different diameters in homemade gaskets, which survived from the days of universal deficit. Kept it as a technical curiosity, but oddly enough, it is sometimes used.
And here is another representative of the past. This is a silentblock presser for “Moskvich”-412. Two neighbors still use them, so I don’t throw them away.
I have a few similar devices, but they have not been used for many years.
There are more usable items. These are wheel bearing press jigs, custom made at a local aircraft factory. The material is not bad, the ones made at the rocket design office were much worse. But the accuracy is lagging, especially compared to what was once done at the Voronezh Mechanical Plant…
There are several universal ball pullers. The favorite is a forked impact wrench if the ball bearing or lug is to be thrown out.
There are wrenches for steering racks.
Various tools for gripping something shallow in the depths, say, pulling out the chain stabilizer debris in a Zhiguli.
Some tools are universal.
Some are highly specialized, such as this mandrel for installing oil seals on front-wheel drive VAZ cars.
Sets of spring ties of different shapes and lengths, selected for different types of suspension springs, are kept together with the tools for unscrewing strut nuts. The best ones are the ones made to order.
Something of the instrument looks very peculiar. What are these?
These strange things I use to hold the crankshaft pulley of different cars while unscrewing its nut in cases when there is no other way.
And here is no less strange contraption.
This is a camshaft clamp of Opel Astra, Vectra, Zafira motors, and also Chevrolet Cruze, Orlando, Aveo of Opel type. It so happened that my customers had a lot of these cars, I had to get into it.
With these and similar engines are often used such non-automotive things as markers and regular stationery “Shtrich” – they are convenient to apply the marks on the timing gears, chain or belt.
With Zhiguli, of course, everything is easier. Here are some wrenches for the crankshaft pulley nut. Homemade powerful – for unscrewing this nut with a starter.
And oil filter removers. Cup one – for Logan.
A recent acquisition is a set for depressing the pistons of rear disc brakes. Useful for those cars where the service and parking brakes use the same pads, used to do this with pliers or a wrench from the “grinder.
Speaking of pliers and other side cutters with round pliers.
Of course, this is not all. A lot of little things, without which it is impossible. It occupies every nook and cranny of a workshop – syringes, funnels, open-end wrenches size from 5,5 to 41, drill bits, taps…
Lots of different fasteners, not new, but good.
It’s all sorted in my leisure time, but I wish I had less leisure time at work. Sorting can wait.
I almost forgot about another important device.
No kidding! This ancient Chinese fan has been working for about 15 years and it properly cools motors before valves adjustment or replacement of antifreeze, and helps out in the heat of summer.
And finally, the most important tools in a mechanic’s work: “liquid key” and adhesive tape.
How to use? With “liquid key” we pour everything that should move freely, and with the tape we reliably fix what should not move
