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Brake Shoes & Drums: When to Replace and How to Match

Shoes and drums are the parts you’ll replace more than any other on the foundation brake, and they wear as a pair — so it pays to know when they’re done and how to get the right ones back on.

When the shoes are finished

Lining down to a quarter inch is the line in the sand — replace before you get there, not after. Glazed, oil-soaked, or cracked linings are out too, and so is a set that’s wearing unevenly side to side. Always do shoes in axle pairs; a fresh set on one side and worn on the other makes the truck pull under braking.

When the drum is done

Every drum has a maximum diameter stamped on it. Past that, or with cracks, deep heat checking, or blue hard spots, it’s scrap — and a cracked drum is never something you machine and reuse. Out-of-round drums show up as pulsing or vibration when you brake.

The FMSI number is your friend

Brake shoes carry an FMSI number — 4515, 4707, and so on — that nails down the shoe’s geometry and lining. Match the FMSI and you’ve matched the shoe across every brand, which is exactly why cross-referencing shoes is so clean. Drums match on size, bolt circle, and weight class.

GBK shoes and drums cross-reference the usual names — Gunite, Webb, Meritor, Bendix. Start in brake shoes or brake drums and check the cross-reference table on the product page, or hand us the FMSI or OE number and we’ll confirm it.


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