The first 2km of Manoeka Road are sealed then another 1.5km of gravel which is much narrower, tighter and undulating. The road ends at a carpark for Otawa Scenic reserve, however a 4wd track continues into the bush from there. A quick google indicates the 4wd track goes about 800 metres to the remains of an old water supply dam.
I rode about 50 metres into the 4wd track which was slippery and had a couple of small mudholes. I stopped at a small river crossing where the track exiting the other side was much rockier and disappeared into the trees.
Going further looks like a @brainflex job on a postie bike.
Stopped at the water crossing
Looking back at where I came in
The ruts would indicate some sort of vehicles come in here regularly
A closer look at the exist on the other side of the water crossing.