Installing A Halda Speedometer Cable Drive Gear In My Saab 99

I recently acquired a 1979 Saab 99, which I am currently refreshing and getting set up for TSD and Time-Speed rallying.  I had a major task of installing a missing air conduit under the dash.  As part of that work I had to establish good access to the area behind the dash.  As a result of this access, I decided to take this opportunity to install a Halda T-Gear to allow me to install one of my Halda Speedpilots which are driven off the Saab’s speedometer cable.  I also might use this connection as a source for a speedometer cable pulse generator for an electric odometer or rally computer.  While the final use and configuration is still not finalized, I did not want to miss the opportunity to install the Halda drive gear at this time.  The photo below shows my initial mock installation to assess the installation issues.

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Initial Mock-Up Installation Of The Halda Drive Gear

The later models of the Saab 99 have a bayonet type connector at the end of the speedometer cable.  What I discovered during my mock-up installation was that the Halda T-gear connector would not fit due to the length of the Saab 99 connector.  The length of the connector would not allow the bayonet connector to fully engage.  I was quite surprised when the Halda gear would not easily fit on the Saab, which has a rally history.  It would have been very simple for Saab to move the lugs on the speedometer cable connection about 1.0 to 1.5mm closer to the end.  I concluded that the best approach was to modify the Halda connector as modifying the speedometer cable connection would have been more complex.

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Halda Equipment Involved

I took all of the pieces down to my basement workshop.  I have had the Halda bayonet end T-Gear drive for several years, as I bought it thinking that I might be able to use it someday in the future.  I also have some other Halda gears in a box that I might also need at some time.   The 36-inch plain end Halda cable was recently purchased from my sometime rally driver Harald von Langsdorff, who was aware of my plan.  In addition, having a supply of cable clips is important for most Halda installations.

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Halda V24 T-Gear With Bayonet Ends

During the mock installation I discovered that it was possible to make adjustments to the Halda connectors.  Note that there are set screws on the central piece of the Halda gear.  These set screws are shown in the image below.

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Close Up Of Halda Gear

If the set screw is loosened then the Halda end connection can be removed.  This is shown below.

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Removal Of Halda End Connection

In a normal Halda end connection end, the actual connection end is held in place by the set screw which is embedded in a circular groove.  I do not have the capability to install an alternative groove, but I decided that I could drill a set screw hole or indentation in which to embed the set screw which would allow me to extend the length of the Halda connector in order to match up with the length of the stock Saab 99 speedometer cable bayonet connector.

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Modified Halda End Connector

I re-assembled the Halda gear and installed in back in the Saab 99.

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Installed Halda Gear

The picture above shows the Halda gear installed with the Halda drive cable directed over to the navigator’s station on the right side of the Saab 99.  When I went to re-install the instrument panel, I found that I had to re-locate the navigator Halda cable to be behind the hole for the speedometer unit.  For the time being I will leave the cable unconnected at the navigator’s station until I decide upon the final configuration.

Hopefully this will help others who want to install Halda equipment in their car.

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