Bronze bearings and bushings: the C932 / SAE 660 workhorse.

Copper, tin, and lead — the lead is the point

C932, known in the trade as SAE 660, is roughly 83% copper with tin, lead, and zinc in the mix. The lead — around 7% — is the whole reason this alloy exists: lead makes the bearing slippery, so a steel shaft can spin inside a bronze sleeve with minimal wear. It's effectively self-lubricating.

That lead also gives C932 its telltale look: darker than brass, often with a slightly speckled or streaky surface where the lead sits. If your bronze ring looks dark and a little mottled, that's the lead talking.

Rings, sleeves, flanges, and thrust washers

Bearing bronze shows up as sleeve bushings (plain rings), flanged bushings (rings with a lip), thrust washers (flat rings), and split bearings (half-shells from engine and gearbox work). Sizes run from finger-sized to dinner-plate.

Fresh from the box they're a medium bronze-brown; used ones come out dark, sometimes nearly black with oil. Color doesn't change what they are — a file scratch still shows bronze underneath. Don't confuse them with babbitt (the silvery bearing metal, a different item entirely) or with steel-backed bearings that have only a thin bronze lining.

Motors, pumps, gearboxes, marine shafts

Anywhere a shaft spins: electric motors, pumps, gearboxes, machine-tool spindles, marine propeller shafts and rudder stocks, and agricultural equipment. Maintenance shops and plant tear-outs produce them by the bucket; machine rebuilds produce the big ones.

Keep bearing bronze with bearing bronze. Don't toss bushings in with mixed bronze solids or brass fittings — C932 is one of the most recognizable bronzes in the trade, and a clean, separated pile is exactly what buyers want to see.

Pull the shaft, wipe the grease

Clean bearing bronze means the steel shaft is out, the heavy grease is wiped off, and there's no babbitt or steel backing hiding in the pile. A magnet check catches steel-backed pieces fast — if it grabs, it's not solid bronze.

Split bearings with visible steel shells go in their own pile, not in with the solid bronze. And keep aluminum-bronze wear parts (the C954 family) separate from C932 — different alloy, different pile. The four grading levers apply here like everywhere else.

Keep reading the brass & bronze dictionary.

Brass & Bronze Dictionary — the full hub of alloy-by-alloy guides. Bronze — the copper-plus-tin family. Brass & Bronze Alloy Numbers — C932 and the rest. Phosphor Bronze — the other bronze sellers meet.

Bearing bronze questions, answered.