How Do I Get My Speedometer Recalibrated

Posted in Performance Chips | Asked on Jun 4, 2010

Every time I pass one of those police radar signs that tell you at what speed you’re driving, it is at least 6-7 miles away from my speedometer.

There are 4 Answers for "How Do I Get My Speedometer Recalibrated"

  1. Leo says:

    it depends on the car mate, im a jaguar technician, if it’s a cable speedometer it’ll be the nylon cable from the clocks to the gearbox frayed, if it’s electronic it’s gonna be expensive to fix for sure, but normally a computer at a garage can calibrate it depending on your make and model, leo

  2. metalmania_06 says:

    If the speedometer is controlled by the ECM, service station (GM, Ford, DC) can recalibrate.

  3. GeorgeB says:

    Your dealer can have your speedometer head pulled and sent to a calibration shop for proper calibration to factory specs. That is the right way to do it. But before you go to that expense, there are some things you should check:

    1) Are you running the correct tires for the car as it was manufactured ? Tires with a different profile, circumference, etc… can cause the speedometer to be off. So verify that first.

    2) If your car is a rear-wheel drive, then most likely the speedometer is driven off a gear attached to the transmission tailshaft, and the cable and gear need periodic lubrication. If the cable is getting dry, you will see jerky indications as you change speeds (used to see that in my ’84 Trans Am when the cable got dry)

    3) Look in the yellow pages in your town and see if there is a shop with a dynamometer (they strap your car down and the drive wheels turn a roller drum that registers true speed at the wheel while they do checkpoints at the speedometer… i.e. they run the car at various speeds at the speedometer and register what the true wheel speeds are at the drum ). This type of facility is usually where folks go when they get a speeding ticket to verify their speedometer. I had to do that once after a dealer maladjusted the speedometer without sending it to the calibration shop. $70 in court costs and $300 addition insurance premiums over 3 years. The calibration shop was cheaper.

    Don’t discount that the police radar sign is off. These things run off a battery most of the time, and as you can imagine, when the battery gets weak, so does radar accuracy. Also not good to compare your speed to another car – their speedometer could be off too…

    Best advice: If your community is speed trap happy and writing lots of tickets, and you are concerned – spend a few bucks and have the speedometer calibrated properly. It’ll be cheaper in the long run…

  4. stush30@verizon.net says:

    Before spending money, ask the police department where in your area the road has signs to measure the mile and speed readings of your vehicle for accuracy. In my area the only true way was to find a shop that had a dyno testing machine and pay for the readings and additional for the calibration.