How do I know what Speedo gear to use?
What gears should I get?
- Count the teeth on the speedometer drive gear.
- Find the gear ratio for the drive axle.
- Calculate tire revolutions per mile.
- Calculate the required tooth count for the driven gear.
- Get the Driven Gear (for your transmission) with the closest tooth count to your calculations.
How does a Speedo drive work?
A car with a digital speedometer uses a speed sensor, which usually consists of a magnet surrounded by a wire coil, quite like the pickup on an electric guitar. The sensor is mounted directly next to a gear on the transmission, and as the gear spins, its teeth whiz by, interrupting the magnetic field on the sensor.
Why do I have to change my Speedo gears?
If you fit larger (or smaller) diameter tyres, your speedo will not read correctly, so you have to swap the speedo drive gear for another one with a different number of teeth to make it accurate again. Land Rover colour coded the speedo gears for easy reference. So here is the list of speedo drive gears and their relevant part numbers.
Why do you have to change the speedo on a Land Rover?
Land Rover made the speedo drive gear interchangeable to allow for different size tyres to be used on the vehicles. If you fit larger (or smaller) diameter tyres, your speedo will not read correctly, so you have to swap the speedo drive gear for another one with a different number of teeth to make it accurate again.
What should I do if my Speedo cable stops working?
Important note on the speedo cable: If your speedo has stopped working, 9 times out of 10 it’s the speedo cable that is at fault. This is what I replaced first, and I would urge you to do the same.
When to replace the drive gear on a Land Rover?
If you can see it turning, your speedo is knackered, if it doesn’t turn, then its time to replace the drive gear. Land Rover made the speedo drive gear interchangeable to allow for different size tyres to be used on the vehicles.
If you fit larger (or smaller) diameter tyres, your speedo will not read correctly, so you have to swap the speedo drive gear for another one with a different number of teeth to make it accurate again. Land Rover colour coded the speedo gears for easy reference. So here is the list of speedo drive gears and their relevant part numbers.
Where is the speedo drive gear located on a Land Rover?
Its advisable to soak the area in a penetrating oil a day before you plan on doing the job. So for this job you will need: Access: The speedo drive gear is located at the back of the transfer gearbox in front of the handbrake drum.
What do I need to slow down my speedometer?
“If you need to slow down the speedometer, you need more teeth on the driven gear.” For example, if your speedometer is showing 60 mph and it should be showing 52 mph, you will need to use a driven gear with more teeth to spin the speedometer cable slower. In this case, you need to add three teeth.
Why is the Speedo not working on my Land Rover?
When it didn’t fix the problem (speedo was still not reading), I had to delve a little deeper to find what the problem was. It turns out it was the speedo drive gear in the transfer gearbox that was worn and not turning the speedo cable. So it was back to the Landy shop to get a replacement drive gear.