Door Lock Replacement, Adjustment and Repairs

Discover your hidden locksmithing talents!

The Basics of removing and replacing residential locksets

First things first!  I have found that certain locks were designed to be virtually impossible to take apart by anyone other than a locksmith. They require special screwdrivers, pins, or wrenches, difficult or impossible to purchase at your local hardware store. Some locks come with these special tools, but are either lost by the homeowner or "unintentionally" taken by the installer to assure future business. I have had the pleasure of cutting off the knobs on more than one lockset in my day. What amazes me is that, on some of these locks, even after I had it cut off, I still couldn't figure out how to disassemble it!! A testament to the ingenuity and creativity of a fine designer!

Fortunately, most home locksets made in the last 20 years are user-friendly, most requiring nothing more than a screwdriver or two to disassemble them.

Lock types revealed!!

The most common styles of residential entry locks today are the tubular or cylindrical lock (graphic left). For purposes of installation or replacement they are similar and you can't really tell the difference between these locks without actually removing the lockset from the door. In fact, if you were to go to the hardware or home store to purchase a lock, chances are there is no indication on the packaging whether the lock is cylindrical or tubular. In function the cylindrical lock is a sturdier beast and is, of course, the more expensive of the two. 

In the olden days... after dinosaurs but before television... many residences used mortise locks (graphic right) A combination deadbolt and spring-type latch, it was installed into a mortise or deep rectangular groove in the edge of the door. The mortise lock is much more time consuming to install and more expensive to manufacture, but one of the strongest styles of lock. Due to cost considerations, it is not used frequently in modern homes. However, it is still available as a "high end" (read mucho expensive) product. Mortise locks are still commonly used in high security business applications.

The other lock commonly used on exterior doors is the deadbolt (left). Deadbolts utilize a latch which is designed to move deep into the door jamb by turning a key, lever, or knob. The deadbolt is meant to back up the relatively low security of an entry lock. The weak link in most locksets is not the lock itself but the door, the door jamb, and strike plate that the latch sets into. That's why many deadbolt manufacturers supply specially reinforced strike plates with long screws to secure it to the door frame.

You can also purchase double-cylinder deadbolts.  No, they aren't twice as strong!  Double-cylinder means that a key is required to open the deadbolt on both the inside AND the outside.  These are commonly used on doors that may allow access to the inside handle, such as doors with glass windows.

Disassembly of your existing lockset...

Remove all visible screws. Sometimes, this is all it takes. Medium to low cost locksets are basically sandwiches, with the inside and outside handles screwed together.  If there are no visible screws, it means that the lock is being sneaky and must be punished! Certain brands of entry locks conceal the screws under the rose... the circular, decorative cover that presses against the door when the lock is assembled. With this style of lockset, the interior door knob must be removed first. Then the rose can be removed by prying it away from the door with the gentle use of a flat blade screwdriver, exposing the screws.

Examine the doorknob carefully. Are there any openings or slots that could accommodate a pin, awl, or flat blade screwdriver? Some locks incorporate a spring catch that can be depressed with one of these tools, allowing you to remove the knob. Many locksets of this type have the removable knob on the inside, for security reasons.

Look at the latch. Are there any holes or openings in it that would allow a tool to be inserted? Some locks are held together by a screw, usually with an Allen head, that is set inches into the door. This screw attaches the latch to the cylinder of the lock, making the lock impossible to disassemble if the door is closed. The problem here is that standard Allen wrenches are not long enough to reach this screw, and you will probably have to go to a local locksmith to get one.

Deadbolts sometimes have metal screw covers installed over the screw heads, to discourage casual removal. These covers can be removed by prying with a thin screwdriver or pulled out using locking pliers. Other deadbolts have internal covers that close over the screw heads when the latch is extended. By turning the key inwards, the screw covers retract to reveal the screw heads.

If after all this, you still can't figure the lock out, and you feel like your back is against a wall, do what NH does...go to the shop of a local locksmith and ask him!

Locksmiths are in business to make money. And it is true that, most of the time, the products they sell will cost a little more than similar products at the big home improvement stores. As a handyman in your own right, you will find it worthwhile to get acquainted with and shop at the specialty stores in your area. These people have worked hard for years to develop their skills and knowledge and have much to offer you.

What I am saying is, if this person can help you out of a tight spot, you at least owe him a sale! I don't think there is anything sleazier than people who will gladly take all of your time for free, but shop elsewhere!

If you choose not to shop locally, the local shop will go out of business.!!

Sometimes, the new lock you purchased won't fit into the old hole. Rats!! What's best way to enlarge the hole?

If the old hole through the door is 2 1/8" or more, there are many entry locks that will accommodate the existing hole, such as a Schlage. I will walk you through the enlarging of the hole, and when I'm through, I won't think less of you if you pack up that lock you just bought and exchange it for one you can install in the existing hole!

Barring the rental or purchase of a special locksmithing jig, proceed as follows:

  1. Get a piece of minimum 1/2" thick wood or plywood that is at least 6" wide by 8" long.
  2. Position the new lockset's template (the guide for drilling that came packed with your new lock) on the piece of wood as if it were the face of the door. Mark the center of the hole and remove the template. Be sure you use the same backset (the distance from the edge of the door to the center of the lockset) as the original lock, or you will have an irreparable mess!!
  3. Using the proper size hole saw, bore completely through the wood. You now have a wood template to guide your hole saw through the door!
  4. Clamp your wood template firmly to the door in the exact position you want the lockset, being careful not to damage the door surface with the clamps. Use wood strips under the clamps on the back of the door if necessary. If you have a problem juggling all these things at once, use some masking or painter's tape to secure the wood strips before clamping.
  5. Before drilling, check one more time that the hole in the guide is the right distance from the edge of the door. If you turned or flipped the guide, it may not be! Make a measurement to be sure. It should be either 2 3/8" or 2 3/4" from the door edge to the center of the hole.
  6. Drill about 3/4 of the way through the door, and stop. Position the guide on the other side of the door, and drill through till the two holes meet. Remove the plug and... if everything went OK... install the new lockset.

Your new lockset is just a tiny bit larger than the old one...

To the left is a typical lockset hole, which was about 1/4 inch too small for the new lockset. Rather than make a hole saw guide, I used a rasp to bevel the outside of the lock hole. Do this on both sides of the door. Be careful not to enlarge the outer edge of the hole too much, or it may show around the rose of the lockset.

Hole saws have a tendency move on surfaces unless the pilot drill bit is into wood. Move is an understatement... they will jump like a cat on a hot tin roof, damaging anything they touch, including you!

So to safely enlarge an existing hole using a hole saw, you must get the hole saw engaged in the hole before using the power drill. By hand, insert the hole saw into the hole and rotate it by hand... back and forth... until it has cut at least 1/4" or more into the door. (Using a rasp as mentioned above can also start the hole.) Repeat on both sides of the door.

Put the hole saw into your drill, insert it into the hole, and bore the hole, drilling 3/4 of the way from one side and then finishing the cut from the other side. Be careful to start your drill at a low speed to control the saw until you are sure the saw won't "jump" out of the hole.

I have tried to impress on you the relative risk of this method compared with the more mainstream method discussed earlier. Whichever method you choose, take your time and be sure of your measurements, because mistakes may be permanent!