Originally Posted by Dave Noble

Your luggage should not be checked through and will need to be rechecked

You do have ( assuming flight on time ) 1 hr 35 minutes between arrival and departure, which is a bit tight

If you are delayed, then the duration between arrival and departure could shrink and there is a bigger risk of missing it

I would suggest booking another flight from Singapore to Sydney ; there are plenty of flights between those 2 airports across several airlines