Speedometers

Is your speedometer reading incorrectly after changing tyre size or gear ratio, or does your project need an extra gauge? In this category you will find separate speedometers with GPS, electric or mechanical signal and scales in both mph and km/h.

Signal type: GPS, electric or mechanical

A speedometer needs a speed signal, and the signal type determines how it is installed. A mechanical speedometer, such as the 3-3/8 inch in-dash model, is typically driven by a cable from the gearbox. An electric speedometer receives pulses from a speed sensor and can usually be calibrated so the reading matches your tyres and gear ratio. GPS models, such as the 5 inch LED Ultra-Lite II, get the speed from satellite signals and are therefore independent of the gearbox, but typically require good reception.

How to choose a speedometer

• Diameter: 2 5/8, 3-3/8 or 5 inch – measure the space in the dashboard or gauge pod before you choose.
• Scale: from 120 to 180 mph or, for example, 190 and 260 km/h. A scale close to the car's actual speed range typically gives a more readable display.
• Appearance: The Pro-Cycle series from AutoMeter is available in chrome, black and white, for example. Ideally choose one that matches your other gauges, such as your tachometers.

Installation and inspection

Check the requirements for power supply, signal and lighting in the installation instructions for the specific part number. Whether a replacement speedometer can be approved at inspection depends on the product and the car – check the requirements for display and accuracy before you install it. If you need more gauges, you can browse the full category of speedometers and tachometers.

Frequently asked questions

Can I use a speedometer with an mph scale in Denmark?

Danish speed limits are in km/h, and some models show both mph and km/h, for example 160 mph/260 km/h. Whether a speedometer is approved at inspection depends on the car and the product, so check this for the specific part number.

Why is my electric speedometer reading incorrectly?

Typically the calibration has not been adjusted to the tyre size, gear ratio or speed sensor. Calibrate according to the instructions, and also check the signal wire and ground connection if the reading fluctuates or drops out.

When is a GPS speedometer an advantage?

When there is no usable speed signal from the gearbox, for example after a gearbox swap, or when you want to avoid a cable and sensor. The reading depends on reception and can react slightly slower to rapid changes.