Hi,

My rear brakes have been making a grinding noise on braking, and now sometimes even at low speeds without braking. The primary brake shoe (nearest to front of vehicle) is worn out to the metal, but only on the top half. The bottom half and the secondary brake shoe pad is quite good and thick.

What are the causes of this type of uneven brake shoe wear please? (The drum is quite scored as well, so shoes and drums need to be replaced).

Thank you!

The primary (leading) shoe will always wear a little quicker than the trailing shoe. Both will wear more nearest the hydraulic cylinder as the bottom ends don't really get closer to the drum.
Whatever the wear, it should be similar on both sides of the car. If one side has worn more, there are a couple of things to check.
The automatic adjusters can get clogged with dust. Any shoe that has to travel further before contacting the drum will wear less, as the others will start working earlier.
A seized wheel cylinder might apply only one shoe.

Due to a process called the self servo effect - which all drums get - it means when travelling forward the front shoe will be pushed down into the bottom bracket and the top half pushes harder as the other pad is been dragged up and pushs harder into the piston at the top

Because the leading shoe has alot more pressure on it - it bites harder and wears faster

Poor adjustment and seizing/sticking om the backplate can also cause shoes to wear weirdly on an axle as 1 side doesnt brake as hard as the other


Replace shoes in axle sets
NEVER DO JUST 1 SIDE

Ziggy