Suzuki Wagon R Manual page 1772

Brake Drum
Inspect drum for cleanliness. Check wear of its braking surface by
measuring its inside diameter.
Inside diameter
Standard : 200 mm (7.87 in.)
Service Limit : 202 mm (7.95 in.)
Whenever brake drums are removed, they should be thoroughly
cleaned and inspected for cracks, scores, deep grooves.
Cracked, Scored, or Grooved Drum
A cracked, drum is unsafe for further service and must be
replaced. Do not attempt to weld a cracked drum.
Smooth up any slight scores. Heavy or extensive scoring will
cause excessive brake lining wear and it will probably be neces-
sary to resurface drum braking surface.
If brake linings are slightly worn and drum is grooved, drum
should be polished with fine emery cloth but should no be turned.
NOTE:
When drum is removed, visually inspect wheel cylinder
for brake fluid leakage. Correct leaky point, if any.
Brake Shoe
Where lining is worn out beyond service limit, replace shoe.
Thickness (lining + shoe rim)
Standard : 6.4 mm (0.25 in.)
Service limit : 3.6 mm (0.14 in.)
If one of brake linings is to service limit, all linings must be
replaced at the same time.
CAUTION:
Never polish lining with sandpaper. If lining is polished
with sandpaper, hard particles of sandpaper will be
deposited in lining and may damage drum. When it is
required to correct lining, replace it with a new one.
PARKING AND REAR BRAKE 5C-5