Trying to get the odometer part of my speedo working.
Actual speedo is good, steady needle and well calibrated.
I found the plastic gear that drives the odometer is damaged - cracked.
In my case it is white. I think different colour gears give different calibration.
Any idea where I can get a replacement?
Any other options?

Is the speedo a UK (Mk1) or an Aust''n (mk2)?
This is a UK Mk1 speedo - the gear wheel is the white plastic piece in this photo, beside the yellow 1/10 mile wheel. This gearwheel doesn't change the speedo ratio.



These speedos were made with a fixed ratio listed on the face of the speedo to indicate the number for turns of the drive wire to equal 1 mile e.g. 1280 turns for a 1275 cooper S. See below



The coloured gears to change ratios were in the speedo housing where the speedo drive cable attached. These different coloured gears only need swapping when changing a speedo to a different car with different gearbox ratio/wheel sizes.

Some specialist repair places may have spares - the gear wheel and the pawl to click it over are the main wearing parts here. Otherwise, can you glue the wheel together?

It is an Aussie speedo.
In this case there are a couple of white gears.
I am referring to the one in the photos.

I have various bits and pieces of speedos I have stripped - I'm not sure, but I have a feeling that the worm gear is different depending on the ratio and the little white gear on the shaft is the same.... but then I think I have a blue gear in my box of bits as well

I'll try to remember to have a look

_________________
did I tell you that I won a trophy?

I found the following articles that explain the workings of the speedo.

In summary, calibration is dependent on tyre diameter and the ratio of the speedo drive cogs in the end of the gear box.

In addition to this the odometer is calibrated by changing the worm gear/worm screw ratio and the gear at the end of the odometer numbers within the speedo. There are several different combinations of these within the Aussie mini and moke range.

And the speedometer appears to be calibrated by changing the location of the needle on the shaft.

My speedo is out of a moke which is in Kph. Thus it has a 20 tooth worm gear, not 32. 20/32 being the ratio between MPH and Kph.

Happy reading for those who are interested. If you are interested in tachos, Anthony Rhodes has a paper on these as well.

http://www.mgb-stuff.org.uk/speedorep.htm

https://obswww.unige.ch/~wildif/cars/do ... repair.pdf