Adding Halda Odometer Calibration Gears To My Rally Navigator Tool Box

This week I substantially increased my ability to be able to calibrate a Halda odometer.  I have both a Halda Tripmaster and a Halda Twinmaster and a number of classic rally cars are fitted with Halda odometers.  Some rallies permit the use of the Halda mechanical odometers with no penalty.   By the way, I would be willing to sell my Halda Tripmaster if the price is right.

Halda Tripmaster (3)

My Halda Tripmaster Is For Sale

As some people will know, the Halda odometers are calibrated by changing the two sets of gears that control the odometer reading – the X-Gears and the Z-Gears.  This week I was able to acquire a complete set of Z-Gears, including the rather rare 45-cog Z-Gear.  The 45-cog Z-Gear does not even appear on the Halda company’s standard calibration table.

I was able to acquire the following Z-Gears: 16, 18, 22, 27, 32, 39, 45, 48, 58, and 70.  These are shown in the image below:


My Complete Set Of Halda Z-Gears

My collection of X-Gears is shown in the photo below.  While it looks like an impressive collection, there are about an equal number of X-Gears that I don’t have.

Halda X Gears (1)

My Halda X-Gear Collection

The table below shows the available calibration factors that I can install with the gears that I now have in hand.  In the table below, the orange shading highlights the Z-Gears that I have on hand and the green highlighting indicates the X-Gears that I have on hand.  In combination, these gears allow the calibration factors indicated by the yellow highlighting.


Halda Calibration Table Showing My Available Gear Combinations

As can be imagined from looking at the above table, I have some other X-Gears that I would like to get over time.  The challenge is that in many cases you never know the calibration factor that you need until you are at a rally, but at that time it is too late to do anything about it.  Luckily, I have some other continuous calibration units that I can also use, but this is another topic.  In addition, I have a device with a set of gears for changing the rotation of the speedometer cable.  Therefore there are a number of ways to get a very accurate reading from a Halda odometer.  Calibrating the Halda odometer before the rally is best so that the range of gears that will likely be needed at the rally can be pre-determined and the necessary calibration strategy can be prepared and implemented.

If you have any questions or comments about the Halda gears or this post, then leave a comment below or you can send me a private email message at the following address: shanna12 at comcast dot net

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