craftsman v20 drill makes a high-pitched whining or grinding noise in speed setting 2, is the gearbox shot?

Diagnosis

The high-pitched whining or grinding noise specifically occurring in speed setting 2 (high speed) on the Craftsman V20 CMCD700C1 indicates a failure in the planetary gear reduction system. In setting 1, the drill uses a higher reduction ratio to provide torque; in setting 2, the gears shift to a lower ratio for maximum RPM. When you hear a whine in only one setting, it means the motor and the primary drive are functioning, but the specific gear set for that speed is either suffering from lubrication starvation or mechanical wear. This usually happens because the factory-applied grease has either migrated away from the gear teeth due to heat or has become contaminated with metal shavings and construction dust. If the sound is a "whine," it is typically a lubrication issue where the metal-on-metal friction is creating a high-frequency vibration. If the sound is a "grind," it indicates that a tooth on one of the planetary gears has chipped or worn down, causing a physical obstruction during the rotation cycle. You can confirm this by switching to setting 1; if the noise disappears, the issue is isolated to the high-speed gear cluster.

How to Fix It

To resolve this, you must perform a full gearbox service. You will need a T10 Torx driver, a small flat-head screwdriver, and a tube of high-pressure synthetic lithium grease (avoid heavy-duty chassis grease, as it is too viscous for high-RPM drill gears).

1. Remove the battery pack and ensure the trigger lock is engaged to prevent accidental activation.
2. Remove all exterior housing screws. Pay close attention to the screws hidden under the grip and the ones recessed in the clutch collar.
3. Carefully split the two halves of the plastic clamshell housing. Use a plastic pry tool to avoid marring the casing.
4. Locate the gearbox assembly. Carefully slide the gear housing off the motor shaft. Be cautious not to lose the small tension springs associated with the speed selector switch.
5. Using a lint-free cloth and a small amount of isopropyl alcohol, wipe away all old, blackened, or gritty grease from the planetary gears and the sun gear.
6. Inspect the gear teeth for any visible chips or "pitting." If the teeth are intact, apply a moderate amount of synthetic lithium grease to each gear. Do not over-pack the gears; too much grease creates "hydraulic lock" and can actually slow the motor down or cause overheating.
7. Reassemble the gearbox, ensuring the speed selector switch is properly seated in its groove.
8. Snap the housing back together and tighten the T10 screws firmly, but do not over-torque them as the plastic bosses can strip easily.

If That Didn't Work

• Replace the Planetary Gear Set: If you found metal shavings in the old grease or visible chips on the teeth, lubrication will not fix the problem. You will need to source a replacement gear cluster specifically for the CMCD700C1 model. Replacing the entire gear assembly is faster and more reliable than attempting to replace a single planetary gear.
• Check the Gear Selector Alignment: Ensure the sliding collar that switches between speed 1 and 2 is fully engaging. If the collar is partially stuck or worn, it may be "riding" between gears, causing a grinding noise. Clean the selector track and apply a tiny amount of dry PTFE lubricant to the sliding mechanism.
• Inspect the Motor Commutator: While the noise is likely mechanical, a failing motor brush can sometimes produce a high-pitched electrical whine that mimics gear noise. Check the motor for excessive sparking or a burnt smell when running in high gear.
• Check for Bearing Failure: Inspect the front spindle bearing. If the bearing is worn, the shaft will have a slight "wobble" that becomes more audible at the high RPMs of setting 2. If the shaft moves laterally, the bearing must be pressed out and replaced.

Heads Up

• Grease Choice: Never use WD-40 or thin oils in the gearbox. These will strip away under load, leading to total gear failure within minutes of use.
• Overheating: If you are using the drill for high-torque applications (like driving large lag screws) in speed setting 2, you are putting immense stress on the planetary gears. Always use setting 1 for high-torque tasks to prevent gear stripping.
• Screw Management: The CMCD700C1 uses several different screw lengths. Keep them organized in a tray during disassembly; putting a long screw into a short hole will punch through the plastic housing.
• Dust Prevention: While the drill is open, use compressed air to blow out the motor vents. Dust buildup in the motor can cause the tool to overheat, which thins the gearbox grease and leads to the noise you are currently experiencing.