In the process of developing my father’s GT750 powered D-Sports racer we found the plastic OEM water pump gear to be inadequate. There are a number of options out there to correct this, they inlcude a press on gear from the UK, an electric water pump kit, or just adapting a commonly available electric water pump. The car however is run total loss, so we really didn’t want to have to add amp hours as that adds weight. An electric water pump would be additional weight and complexity too. Ultimately we decided to stick with the mechanical pump. The added bonus is that it leaves our mechanical tachometer in place, and for the sake of authenticity, and the spirit of vintage competition, this solution seems to be the correct one.
For this gear, the approach is novel in that it utilizes the steel hub from the OEM plastic gear. This allows the gear to be removed without splitting the cases, just like the factory intended. The GT750 billet water pump gear is available for purchase for $100 plus shipping, the hub from your broken plastic gear will have to be supplied so that thew billet gear can be shrunk fit to your hub.