The New Zealand TT moved from Waiheke - 1931 to 1950 to Seagrove Airfield.
Some details have already been posted on here.

In the NSCC thread has been photos of Car Racing.

Here the Airfield - aerial view.

Name:  Seagrove #037 Seagrove Airfield aerial photo 1940's showing runways .jpg
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The TT Track outlined over the Airforce Map with notes by : " jellywrestler " aka Graeme Staples.
Cars only used the Runways but the Bikes used other parts of the area.

Name:  Seagrove #038 Aerial view showing TT course - Air Frce Museum photo sml notes Graeme Staples.JPG
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Size:  178.7 KB