How to Fit a New Speedometer Cable in a Car

How to Fit a New Speedometer Cable in a Car

A speedometer is hands down the most overlooked component of a car. But a bad speedometer can land you many unwanted speeding tickets. Luckily fixing a speedometer is not an effort requiring a job, and installing a new speedometer cable is all that is required. However, there are some things you need to be mindful of before fitting a new cable. Read along to learn how to fit a new speedometer cable on your own.

Signs of a Bad Speedometer Cable

A speedometer works by calculating the rate of wheel turns in a car. A fault in the speedometer’s cable can give inaccurate readings of a car’s speed, causing the person to overspeed without knowing it. Therefore, it is necessary to change the speedometer cable as soon as possible.

A speedometer cable can begin to falter due to many reasons. Knowing how to check a car’s instruments can help you identify the signs which indicate a fault in the speedometer cable. Some of these signs of a bad speedometer cable are mentioned below:

  • One of the most apparent signs of a fault in the speedometer cable is the faulty reading on the speedometer. The needle on the speedometer starts fluctuating irregularly or stops working entirely if the cable is either broken or can no longer fit in the sockets due to wear and tear.
  • If you notice that the needle starts to move very sluggishly, it might indicate that the oil from the gearbox has started to seep up into the speedometer cable, causing it to malfunction.
  • Another sign of a faulty speedometer cable is a tapping or a squealing sound coming from the dashboard.

Note: A power steering can also produce squealing noises in case of reduced steering fluid in the car. Make sure you regularly change the power steering fluid.

  • You can also visually observe the speedometer cable to see if the cable is broken or damaged from anywhere.

If you notice any of the signs mentioned above in your car, it is time for you to replace the old speedometer cable and fit a new one in the speedometer.

Replacing a Speedometer Cable


Things you will need

Following are the things you will need in order to replace a speedometer cable

  • A screwdriver
  • A new speedometer
  • A new gasket
  • A dielectric grease
  • A pair of circlip pliers

How to Remove the Speedometer Cable

Follow the steps mentioned below to remove the speedometer cable:

  • You need to start by opening the car’s bonnet and removing the cover on the engine.
  • Disconnect the car’s battery. Make sure you check the battery leads and connections before you remove them.
  • Now you need to look for a thick black speedometer cable coming from the instrument cluster that is leaving the car’s body.
  • Once the cable is spotted, now you need to remove the nuts and bolts that hold the instrument cluster present on the dashboard in place.
  • Slightly pull the instrument cluster out. Most cars have the cable attached to the speedometer with a knurled thimble nut, which you can loosen by hand.
  • Pull the cable out of the firewall passage.
  • Now loosen the knurled thimble nut that goes into the transmission by hand and use a pair of pliers to squeeze the circlip on the cable to let it loose.
  • Using a screwdriver push the grommet out of the firewall along with any additional brackets that might hold the cable in place.
  • Now you can pull the old cable out of the car.

How to Fit a New Speedometer Cable

Once the old cable has been removed, you can now install the new cable by following the steps listed below.

  • Take your old speedometer cable along when buying a new cable so that you can get the right cable suited for your car.
  • Now you need to push the top head of the speedometer cable through the car’s firewall.
  • For the next step, use a dielectric grease solution to grease the speedometer cable.
  • Now get a small screwdriver and push the grommet of the cable into the firewall’s opening. It is the same opening from where the grommet of the old cable was taken out earlier. A grommet ensures that the cable stays in place and does not get damaged by constantly coming in contact with the sharp metal edges of the firewall opening.
  • Now you have to tighten the knurled thimble nut end of the cable in the speedometer in the instrument cluster.
  • Place the new gasket on the square end of the cable so that it fits properly on the transmission and no oil seeps out from the gearbox.
  • Use the circlip pliers on the circlip connection to secure the square end of the speedometer cable onto the transmission and tighten the knurl thimble nut on it.
  • Make sure you reconnect any clamps or guide clips that hold the cable in its correct place.
  • Now reinstall the cover on the engine properly.
  • Lastly, put the instrument cluster back in place.

Ensure there are no unnecessary kinks or bends in the speedometer cable; otherwise, the reading on the speedometer may falter.

Once the speedometer cable has been replaced, start the car and check if the speedometer is giving an accurate reading; as a quick test, put the car in reverse and check if it gives an average speed.

Additional Measures

If the speedometer still fails to give an accurate reading, you might want to check the voltage regulator and fit a new voltage regulator if necessary.

You can enhance the speed of your car by getting new tires but do bear in mind that new tires are expensive. To make the most out of them, you should have your car’s tires rotated often to improve your car’s speed and performance.

Knowing the exact speed of your car is essential to avoid any speeding accidents or speeding tickets. Therefore, it is important to have a functioning speedometer. Learning how to fit a new speedometer cable is an inexpensive and easy task that can ensure you don’t overspeed beyond the speed limits and saves you unnecessary hassle at the mechanics.