Road salt is the reason a brake mechanism seizes before it wears, and 440C is the cheapest way to stop that. Automotive & Electric Vehicles duty is shock load, wide temperature swings and electrical erosion from the inverter; the material is what decides whether the bearing survives it.
| Industry duty | shock at the wheel end, 15,000 rpm in the e-drive, and inverter shaft voltages |
|---|---|
| Typical media | road spray, brake dust, gear oil, glycol |
| Housing temperature | −40 to +150 °C |
| Material and grade | 440C martensitic stainless steel |
| Hardness | 58–60 HRC |
| Temperature ceiling | 250 °C |
| Corrosion / chemical | fresh water, food and mild chemicals; pits in chlorides |
| Relative cost | ≈3× of a standard 52100 bearing |
A brake caliper bearing lives in the worst place on the vehicle: 250 °C from the disc on one side, salt spray and brake dust on the other, and long periods of inactivity. A chrome steel bearing rusts into its own mechanism and the parking brake sticks. 440C resists that at nearly the same hardness, and its 250 °C ceiling matches the brake-side temperature.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| EPB caliper mechanism | 440C thrust bearing | 440C thrust bearing or bush, H1 grease | Brake heat plus salt spray; stainless avoids a rust-locked mechanism. |
| Exposed chassis joint | Spherical plain | 440C ball, PTFE liner | Salt reaches the ball; stainless keeps rust from pushing the liner out. |
| Sensor bearing / encoder | Deep groove ball | 440C, 2RS, low-torque seal | Rust on the raceway changes the air gap and the signal. |
| Material | Fit here | Choose it when |
|---|---|---|
| 440C | Best fit | Salt-spray positions with brake heat, where a rusted mechanism is the failure mode. |
| 100Cr6 / 52100 | Workable alternative | Sealed positions inside the driveline where salt never arrives; zinc-nickel covers the rest. |
| Si3N4 | Workable alternative | Where brake heat at the bearing seat exceeds 250 °C. |
Better than 52100 by a wide margin, but it will still show corrosion at the seal lip after several seasons. The seal does most of the work.
The caliper mechanism bearing or bush rusts in place during months of inactivity. Stainless or a coated mechanism, plus use, keeps it free.
To 250 °C. Above that the temper is lost, which is why a track-use caliper needs a different design, not a different grade.
Hardness, temperature, corrosion and equivalents for 440C stainless.
Read →Typical duty, recommended types and suffixes for automotive & ev.
Read →Wheel end & driveline — wheel hub pairs, gearbox shafts and e-drive rotors.
Read →E-drive & high speed — e-drive rotor and gearbox positions where inverter voltage erodes the raceway.
Read →Send the position, bore size, quantity and the medium it sees. We reply with the material certificate, clearance class, lubricant and price within 30 minutes on working days.