A Weiser door lock assembly installs basically the same as most other residential door handles and locks. They have three basic components: the inside handle, the outside handle and the internal lock piece. A fourth piece is the strike plate that mounts on the edge of the door. You can install the lock using basic household tools within a few minutes, assuming the door handle cavity is the appropriate size. The job itself takes only a few minutes, however, finding the right Weiser lock size for a previously cut door handle cavity might take quite a bit longer.
Remove the current door handle lock on the door using a Phillips-head or flathead screwdriver, depending on the hardware installed. Unscrew the two main bolts keeping the assembly together. Remove the bolts and pull out the handle part that is on the back of the door.
Pull out the front handle, and use the Phillips-head screwdriver to remove the strike plate screws. Pry the plate off the door if it is stuck using the flathead screwdriver. Remove the internal latch mechanism by unscrewing its securing bolts first and then pulling the old latch out of the side of the door.
Take the old handle with you to the hardware store, including the strike plate, and compare the available Weiser door locks. Buy the model that matches the dimensions of the old handle lock. Unpack the lock kit and spread the parts on a table near where you will work.
Insert the centre latch bolt mechanism first by installing it though the hole in the edge of the door. Place the two screws into the top and bottom of the bar strike plate and attach them to the door using a screwdriver. Insert the rear door handle cylinder though the latch bolt so that it meshes with it. Test it by turning the handle.
Insert the front door handle portion so that it meshes with the cylinder shaft of the rear door handle. Insert the securing bolts and tighten them with a screwdriver so the assembly holds together but is not fully tightened. Twist the handles on each side to test that the assembly is working correctly.
Tighten the bolts so that the two handle halves come together snug with the door and the latch. Test the assembly one more time by working the handles and the lock.
You can use a larger Weiser lock and strike plate if desired, but you will have to enlarge the door cavity to fit the parts. This involves using a router or drill, matching bit and a wood chisel.
Don't assume any Weiser lock off the shelf will work for you needs. Locks and handle sets between brands come in different sizes, so when replacing one you need to compare measurements to ensure a proper fit. Otherwise the new Weiser latch component may not work correctly.