Improving Your Home Security

How To Replace Keyed Cylinder Lock On A Sliding Glass Door

by Clifton Montgomery

If you have sliding glass patio door, you may need to replace the lock eventually. Sliding glass doors commonly use keyed cylinder locks, which operate with a knob or latch attached to a cylinder. You should be able to install a new keyed cylinder lock yourself. Here are some tips to install a replacement keyed cylinder lock on sliding glass patio doors.

Prepare to Work

For this project, you need: 

  • tape measure
  • soft cloths
  • glass cleaner
  • Allen wrench
  • Phillips screwdriver
  • masking tape
  • keyed cylinder lock set

Open the door all the way, and loosen the trim plate screws by turning the screws to the left with the Allen wrench. Use the Phillips screwdriver to loosen the handle screws and the lock keeper's plate.

Measure the Screw Holes and Check Teeth Size

Take the handle off the spindle ( a D-shaped square tube), remove the spindle, then detach the trim plates. Get measurements of the screw holes in the door and the thickness of the door frame. Use the measurements as a guide to buy a cylinder lock set from a hardware store.

Look for the teeth on the old lock commonly located on the silver hook. Compare the size of the teeth to the new lock. If you need to change the teeth size, replace it with one of several teeth that commonly comes in the package. Detach the screw on the old teeth to remove it, and install the new teeth in place.

Attach the Lock

Clean the track of the door with a damp cloth. Open the door partially, and set the front panel of the handle in the interior of the door frame where the old lock was.

Position the handle so the screw holes on the handle are in alignment with the screw holes on the door and the teeth facing the door jamb (vertical trim). Secure the handle temporarily with masking tape.

Set the back panel of the handle on the exterior of the door frame. Align the screw holes on the handle and door, then secure the handle temporarily with masking tape.

Remove the tape, and secure the handles to the door with the screws included in the package. Don't make the connections tight, or you risk binding them to the door. Clean residue left by masking tape with window cleaner and a clean cloth.

Test the lock for proper operation. If the lock doesn't work, the old lock is stuck, or you don't trust your skill, contact a locksmith.