I. Preparation
Tools and Materials
New lock cylinder (must match the original lock model)
Phillips screwdriver or Allen wrench
Pliers (optional)
Lubricant (e.g., WD-40, for rusty or stuck screws)
Flashlight (to inspect internal components)
Identify the Cylinder Type
Measure the length of the original cylinder (common sizes: 60mm, 70mm, 80mm).
Determine if it's a single-sided cylinder (key only on the exterior) or double-sided cylinder (key required on both sides).
II. Remove the Old Lock Cylinder
Step 1: Remove the Inner Door Panel
Unscrew the fastening screws on the inner handle plate (typically located at the base or edge of the handle).
Gently detach the inner handle and plate to expose the lock mechanism.
Step 2: Loosen the Cylinder Fixing Screw
Locate the horizontal fixing screw near the latch on the door's edge.
Use a screwdriver to loosen and remove this screw.
Step 3: Extract the Old Cylinder
Insert the key into the cylinder and turn it to a vertical position (parallel to the door).
Pull the cylinder outward from the exterior side. If stuck, gently wiggle the key with pliers for assistance.
III. Install the New Lock Cylinder
Step 1: Insert the New Cylinder
Slide the new cylinder into the door from the exterior, ensuring the keyhole faces upward.
Turn the key to align the cylinder's internal drive rod with the latch mechanism.
Step 2: Secure the Fixing Screw
Reinsert and tighten the horizontal fixing screw on the door's edge.
Avoid over-tightening to prevent cylinder deformation.
Step 3: Reattach the Handle and Plate
Reinstall the inner handle and plate, then tighten all screws.
Test the handle's rotation and ensure the latch extends/retracts smoothly.
IV. Testing and Adjustments
Key Test
Insert the key and turn repeatedly to check for smooth operation. Apply lubricant if needed.
Confirm the latch fully extends and retracts.
Interior/Exterior Function Test
Test the inner handle's ability to lock/unlock.
For double-sided cylinders, verify both sides work with the key.
V. Important Notes
Compatibility
Ensure the new cylinder matches the original lock's size and type.
Bring the old cylinder to a hardware store for comparison or provide the lock's brand/model.
Safety Tips
Keep the door open during replacement to avoid accidental lockouts.
Use WD-40 on rusty screws before removal to prevent stripping.
Complex Issues
If the cylinder is broken or components are jammed, contact a professional locksmith.
For electronic/smart locks, follow the manufacturer's instructions.