634ZZ bearing
The 634ZZ is a miniature ball bearing with a 4 mm bore, 16 mm outside diameter and 5 mm width, metal shielded on both sides.
Size & specs
| Type | Miniature ball bearing |
|---|---|
| Bore (ID) | 4 mm (0.157 in) |
| Outside diameter (OD) | 16 mm (0.63 in) |
| Width | 5 mm (0.197 in) |
| Seals / shields | ZZ: metal shielded on both sides |
Cross reference: same bearing, other brands
| SKF | 634-2Z |
|---|---|
| NTN | 634ZZ |
| NSK | 634ZZ |
| FAG | 634-2ZR |
| Timken | 634-ZZ |
| Koyo | 634ZZ |
Budget brands usually sell this as 634ZZ. Add C3 if your old bearing was stamped C3 (looser fit for hot-running motors).
Where to buy
Other versions
Other bearings with a 4 mm bore
Questions
What size is a 634ZZ bearing?
4 × 16 × 5 mm (bore × outside diameter × width).
What does ZZ mean?
ZZ means metal shields on both sides. Shields have less drag than rubber seals and suit higher speeds, but they don't keep out water or fine dust as well.