That implies the speedo input doesn't have any pull-down resistive path of its own. So keep the 47k (or 10k) in place, since it provides a path for the capacitor's charge/discharge current.Tried to run without any resistor at all and it wouldn't work.
The link to the Hall sensor data is helpful. It shows the sensor has an internal pull-up resistor Rpu (as we assumed), and gives the max sink current as 20mA. The 3k3 resistor limits the current to ~4mA worst case, so you're well within the limit.