Thread: speedo error

My County, and just about every other one I have heard of, has a speedo error of around 7% with the speedo reading higher than the road speed. This being the opposite of yours, it would suggest a gearing problem, possibly as suggested.

Check the accuracy of the odometer readings - these, being fixed gearing would show that it is a gearing problem.

There is a possibility, however, that it is not a gearing problem. Unless I am mistaken the worm that drives the speedo gear is only clamped between the output yoke and the output bearing, so that if the nut on the end of the output shaft is slightly loose, the worm can slip causing the speedo to under-read. This usually results in an erratic speedo reading, but is still a possibility.

John

That is exactly the error I had with my Series III speedo and odometer. If the speedo said 90, I was doing 100. If the odometer said I had travelled 100km, I had really gone 107km.

In my case, I am almost certain it was because the vehicle was fitted with a SWB speedo designed for smaller tyres than the 750x16s on my LWB. By the time I learned that there was a way to check, I had sold the vehicle, so I can't be 100% sure.

I believe it was JDNSW who posted the information about how to check for that problem.

As far as i know the speedos are the same gearing for all coil sprung utility Landrovers, and the intended OD of tyres is the same, within legal speedo error limits. Other Landrovers using the same drive have different drive gears (but same worm), and it is possible that this is the case with the OP, particularly if the gearbox/transfer case came from a Rangerover.

Since I have 2, 110 Isuzu Lt95 in my yard I could compare the nylon gears that the cable drives of between each the one that indicates true to the one that does not, to see if they are the same or not?
Or order a replacement nylon gear and pull it out and see the if the new one is the same, only have to pull it out once then.
Or is the nylon gear not the one that is different is the diffance the metal one in the transfer box?

Nylon gear is the difference.

John