Buy a 3/8 drive 6-point set that actually contains 8 through 19 mm, shallow and deep, and a ratchet. Wait on another large-size impact set if the bolt in your hand is a case screw. Torque specs that sit at 20 ft-lb and up are the torque wrench. The first-tool list is the CB garage guide.
Which socket fits the bolt
| Job | Use | Skip | Shop |
|---|---|---|---|
| Case covers and the bolts you touch every service | 3/8 drive, 6-point, 8 to 14 mm | A 12-point socket on a soft hex | View Case covers and the bolts you touch every service (affiliate) |
| Recessed nuts in the larger sizes | Deep 17 to 19 mm here, or a 1/2 drive set past that | A shallow socket that never reaches | View Recessed nuts in the larger sizes (affiliate) |
| A piece-count kit missing 8 to 14 mm | The metric half of a set that includes them | Hoping the SAE row is close enough | View A piece-count kit missing 8 to 14 mm (affiliate) |
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The sizes that show up every service
Classic CB fasteners are metric. The ones you remove to get into the engine are mostly the small end: 8, 10, 12, and 14 mm. Axle and chassis nuts step up through 17 and 19 mm. A set that starts at 17 mm is a supplement. It is how the last guide on this site described a 1/2 drive impact set, and that description still stands.
Six-point matters more than the logo. Old hex heads are soft. A socket that bears on the corners rounds them. Once the head is round, the correct torque spec is a story you tell while you drill.
The set
Larger recessed fasteners stay on the 1/2 drive deep set in the garage guide. Electrical faults are not a socket problem: use the multimeter guide before you order a stator.