Speedometer cable and its replacement

The speedometer is that component, without which not a single car can do. With this mechanism, you can accurately determine how fast the vehicle is moving. According to the rules of the road, it is forbidden to drive with a broken element on the car. 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. These cars were equipped with all the cars up to the 90s. Closer to the "zero" on the machine began to install electronic speed sensors. The type of cable depends also on the type of instrument cluster. Is this element in the gearbox. The speedometer cable (VAZ-2113 including) reads data from the transmission shaft and transmits information to the instrument panel. So the driver can monitor the speed of the car in real time.

Device

The device also includes an odometer. With it, you can read information about the car's mileage. The instrument panel has two scales. The one on top is responsible for the full run of the car, and from below - for the day (up to a thousand kilometers). All readings are read from the cable. The speedometer and odometer are directly connected. The design of the element assumes the presence of high-speed magnetic nodes. Due to the force of the magnet's rotation, a stream of eddy currents is formed. Passing through the coil, the currents create a magnetic field. Thus, the arrow of 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 a device such as a speedometer cable, 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 reducer. On rear-wheel drive vehicles, it also serves as a secondary shaft. The position of the arrow on the scale depends on the strength of the magnetic field in this gearbox. So the driver gets accurate information about the mileage and current speed of the car.

Is there an error

It is worth noting that the readings on the instrument panel (if this is a mechanical element) may differ slightly from the real ones. But often the error does not exceed five percent. So, the speedometer readings are affected by the size of the wheel disks, the tire profile and gear ratio (if it is a rear-wheel drive car). On absolutely identical cars from the plant put different bridges, with a different gear ratio (an average of 3.9 to 4.4 for classic VAZs). Therefore, many manufacturers began to abandon the technology of the cable speedometer. Now the cars use an electronic sensor. Its error does not exceed one percent. одну колодку с проводами). Yes, and replace it much easier (just need to disconnect one pad with wires).

Basic Faults

Such a detail, like the cable of the speedometer drive, is highly reliable. But to exclude problems with this mechanism is not worth it (especially since the technology is quite outdated). Thus, during operation, the arrow on the instrument panel may twitch or stop reacting at all to speed changes. How to be in this situation? It is not necessary to replace the speedometer cable. The reason may be a banal loosening of the nut, which fastens the flexible shaft to the actuator. In this situation, the speedometer winding will help, or, more precisely, the tightening of the nut itself. In half the cases the problem goes away by itself. But there are more significant malfunctions, in which only repair of the speedometer or its complete replacement will help. So, the drive shaft itself is out of order. It breaks off. The malfunction is accompanied by a characteristic knock. The arrow stops showing the correct information. What could be the reason for this phenomenon? An open in the drive is due to the presence of contaminants inside it. Also, the opposing spring breaks. In any case, it is required to replace the speedometer cable (if the operations with the tightening of the nut did not help). Below we will look at how to change this element by yourself.

Dismantling

First of all, we need to remove the old mechanism. To do this, it is necessary to de-energize the vehicle's on-board network 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, you need to find the junction of the mechanism and unscrew the fixing bolt, which fixes it. Regardless of whether the front-wheel or rear-wheel drive car, the end of the cable is on the gearbox. For convenience, it is better to use the observation pit. So, unscrew the fixing bolt and remove the clamping nut that connects the cable to 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 side of it we take out the second end of the cable.
When dismantling, try not to damage the rubber seal.

Installation

The order of installation of the element is reversible. To do this, lay a new cable speedometer through the panel in the cabin and "pull" it to the transmission. Try to fix the element in the same way as the old one lay. If it 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 "podkapotkoy." 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:

• When buying a new item, be sure to check the length of the cable. On the same models of cars, its size can be different. It is not allowed to use elements shorter or longer than the standard value.
• Before installing a new speedometer cable, it is recommended to apply a layer of lubricant to it. This will prevent premature failure of the mechanism. You can use the usual workout or "Nigrol".
• When installing, try to lay it as if it were from a factory. It is inadmissible that the cable is in contact with moving parts. Do not use tight hinges 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.

Winding of the speedometer

A few words about this device, like "krutilka" for the speedometer. The element is designed to rewind the odometer reading. It is connected via the diagnostic connector OBD. The device intervenes in the control unit and independently winds the mileage indication. At the heart of the machine is the CAN bus. The mileage is corrected not only on the instrument panel, but also in all duplicate units. Determine the cheating with this device is quite difficult. Who uses such devices? They are used on the owner's cars in order to "weld" on the fuel. So, the car passes 100 kilometers, and on the instrument panel and in the ECU the mileage in 110 is shown. The cost of such a device is 3.5 thousand rubles.

Repair or replacement?

If you doubt whether to repair the speedometer or replace it completely, it is worth paying attention to the price of the mechanism. On average, its cost does not exceed two hundred rubles. Therefore, it makes sense to replace the whole element. Moreover, suitable repair kits are not always available.

Customize

That the speedometer readings were with a minimum error, experts recommend additional adjustment. To do this, measure the distance from the start of the damper to the clutch fork. The parameter should be 86 (+5) millimeters. Next, measure the clearance between the end of the damper and the tip of the cable. The normal parameter is 65 millimeters with a margin of 5 mm. If your readings differ from the factory ones, you should adjust the tension of the cable with a key using a lock nut. After that you can start using the car.

Conclusion

So, we found out how the speedometer cable works and how to replace it with our own hands. As you can see, this is a very necessary element, without which riding on any car becomes unsafe. After all, subjectively determine the speed is not always possible, especially if you are moving on a wide highway.