Although the rear brakes adjust themselves, they don't always adjust properly.
As the brake shoes wear down, the auto adjusters move the brake
shoes closer to the drum so the foot brake travel isn't increased.
There is a self adjusting mechanism at the base of the handbrake lever too but this too can have issues.
When the brake shoes are worn or the cables stretch it can be outside the adjusting range.
This will create slack on the handbrake cables to both rear brakes.
The handbrake lever will have to be moved further before it moves
the brakes and even further before they start to touch the brake drums.
As the brake shoes wear down, the resting position of the lever will be higher
and higher. Eventually the ideal resting position for the handbrake will fall in
between two clicks of the ratchet on the handle as you pull it. The lower position
won't be enough and the brakes won't stop the car creeping away, the higher
position will take some strength to pull to and can slowly stretch the cables.
At this point you can either fit new brake shoes or adjust the handbrake.
Adjusting The Brakes
Thanks to Chris Ryu for the information
First we need to ensure the brake shoes are wearing and braking evenly.
Jack the car up and remove back wheels. Undo the tiny torx screw (careful not to round it off!),
remove the drum and clean to avoid harmful dust entering the air. You should see a small gear.
As you turn this gear, you'll hear a click. This is the capture mechanism that forwards the adjuster on
in normal use and also stops the adjuster from traveling backwards which would leave you with no brakes.
Other sites tell you to adjust this wheel as it is but it makes it hard to adjust the gear back without 2 screwdrivers.
I'll tell you how these are supposed to work, not just tell you to jab screwdrivers in it.