1. Measure the outside diameter
Measure across the widest friction surface in millimetres. Common heavy-duty commercial vehicle sizes include 430 mm, 420 mm, 400 mm and smaller platform-specific diameters.
2. Record the friction and hub dimensions
Measure the friction lining inner diameter, the total assembly thickness and the hub height from a stable reference surface. Photograph the ruler or caliper in position so the measurement can be reviewed.
3. Count and measure the spline
Count the internal spline teeth and measure the spline outside diameter. A disc with the correct outside diameter can still be incompatible when the spline profile differs.
- — Spline tooth count
- — Spline outside diameter
- — Hub projection on both sides
- — Damper spring count and arrangement
4. Add the application information
Include the truck model, engine, transmission, OE number and operating environment. Mining, long-haul, bus and construction applications may require different configurations even at the same nominal diameter.