Cable speedometer and its replacement

The speedometer is that component, without which nocosts no car. With this mechanism, you can accurately determine the speed with which the vehicle is moving. According to the rules of the road, driving with a broken element on a car is prohibited. Any driver should know how to replace this element and identify this fault. So, let's consider what the speedometer cable is, how it works and how to replace it.

Characteristic

It should be noted that this element is used only in mechanical speedometers. Those were equipped with all cars until the 90s.

Closer to the "zero" on the machine began to installelectronic speed sensors. The type of cable also depends on the type of instrument cluster. This item is in the gearbox. The speedometer cable (VAZ-2113 including) reads data from the transmission shaft and transmits the information to the instrument panel. So the driver can control the speed of the car in real time.

Device

The mechanism also includes an odometer.

With it, you can read information aboutrun of the car. On the instrument panel there are two scales. The one on top is responsible for the full mileage of the car, and the bottom - for the day (up to a thousand kilometers). All readings are read from the cable. Speedometer and odometer are directly related. The element design assumes the presence of high-speed magnetic nodes. Due to the magnet rotational force, a flow of eddy currents is generated. Passing through the coil, the currents create a magnetic field. Thus, the speedometer on the instrument panel begins to move along the scale. The rotational force is proportional to the frequency with which the magnet rotates. When reviewing the device of such an element as a cablespeedometer, the question arises: how the arrow does not fall, if the gear ratio on the shafts of the box is different? Everything is very simple. Inside the element is a small gearbox. On rear wheel drive cars, it also performs the function of a secondary shaft. The position of the arrow on the scale depends on the strength of the magnetic field in this very gearbox. So the driver receives accurate information about the mileage and the current speed of the car.

Is there an error

It is worth noting that the readings on the instrument panel (if it is a mechanical element) may slightly differ from the real ones. But often the error does not exceed five percent.

So, the speedometer affects the sizewheels, tire profile and gear ratio (if it is a car with rear wheel drive). On exactly the same cars from the factory put different bridges, with a different gear ratio (on average from 3.9 to 4.4 for the classic VAZ). Therefore, many manufacturers began to abandon the technology of cable speedometer. Now on cars using an electronic sensor. Its error does not exceed one percent. Yes, and it is much easier to replace it (you need only disconnect one block with wires).

Major faults

Such a detail as the speedometer drive cable,differs in high reliability. But excluding problems with this mechanism is not worth it (especially since the technology is very outdated). Thus, during operation, the arrow on the instrument panel may twitch or stop responding at all to a change in speed. How to be in this situation? It is not necessary to replace the speedometer cable. The reason may be the banal loosening of the nut that secures the flexible shaft to the drive. In this situation, help speedometer winding, or rather, the tightening of the very nut. In half the cases, the problem goes away by itself.

But there are more significant faults, withwhich will only help repair the speedometer or its complete replacement. So, the drive shaft itself fails. It breaks off. Fault is accompanied by a characteristic knock. The arrow stops showing accurate information. What could be the reason for this phenomenon? Drive breakage occurs due to the presence of dirt inside it. The spring of the opposing spring also breaks. In any case, it is necessary to replace the speedometer cable (if the operations with tightening the nut did not help). Below we will look at how to change this element with your own hands.

Dismantling

First you need to remove the old mechanism.To do this, de-energize the vehicle electrical system by removing the negative terminal from the battery. Next, disconnect the old item. How to remove the speedometer cable with your own hands? To do this, find the junction of the mechanism and unscrew the mounting bolt that fixes it. Regardless of whether the front-wheel drive or rear-wheel drive car, the end of the cable is on the gearbox. For convenience, it is better to use the inspection pit. So, unscrew the mounting bolt and remove the clamping nut that connects the cable with the speedometer in the cabin.

Next, go to the second part of the dismantling. To completely remove the element, you need to partially disassemble the instrument panel. From the back of her hand to extract outside the second end of the cable.
When dismantling, try not to damage the rubber sealing gasket.

Installation

The installation of the item is inverse to removal.To do this, lay the new speedometer cable through the panel in the cabin and "pull" it to the transmission. Try to secure the element in the same way that the old one lay. If this is a front-wheel drive car, where the gearbox is installed in the engine compartment, the mechanism is laid through a special hole in the partition between the cabin and the “undercap”. All rubber seals are installed in their places. Depending on the brand of the car, there may be a different number (but in any case at least two).

Helpful Tips

When performing operations with this mechanism, pay attention to the following points:

• При покупке нового элемента обязательно проверьте cable length. On the same car models, its size may be different. Items that are shorter or longer than the standard size should not be used.
• Before installing the new speedometer cable, it is recommended to apply a layer of lubricant on it. This will eliminate the premature failure of the mechanism. You can use the usual testing or "Nigrol."
• When installing try to lay it as withfactory. It is not permissible for the cable to come into contact with moving parts. Also, do not use tight loop when laying. So you will increase the load on the core of the cable, and it will quickly fail even with a good layer of oil.

Speedometer winding

A few words will tell about such a device as"Krutilka" for the speedometer. The element is designed for winding odometer readings. It is connected via the OBD diagnostic connector. The device intervenes in the control unit and independently winds the mileage readings. The device is based on the CAN bus. Mileage is adjusted not only on the instrument panel, but in all duplicate blocks. To determine the cheat using such a device is quite difficult. Who uses such devices? They are used on host cars in order to “weld” on fuel. So, the car travels 100 kilometers, and on the instrument panel and the computer, the mileage is shown at 110. The cost of such a device is 3.5 thousand rubles.

Repair or replacement?

If in doubt, repair the speedometer or replace it entirely, you should pay attention to the price of the mechanism.

On average, its value does not exceed two hundred rubles. Therefore, it makes sense to replace the entire element. Moreover, suitable repair kits are not always available.

Customize

To read the speedometer with a minimumaccuracy, experts recommend additional adjustment. To do this, measure the distance from the beginning of the damper to the clutch fork. The parameter should be 86 (+5) millimeters.

Next, measure the gap between the end of the damper andthe tip of the cable. The normal parameter is 65 millimeters with a margin of 5 mm. If your readings are different from the factory, you should adjust the tension of the cable with a key using the locknut. After that, you can start using the car.

Conclusion

Итак, мы выяснили, как устроен тросик спидометра and how to replace it with your own hands. As you can see, this is a very necessary element, without which driving on any car becomes unsafe. After all, it is not always possible to subjectively determine the speed, especially if you are traveling along a wide highway.