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How to Change Your Lock Cylinder: Replacement Guide

Tom has 17 years of experience as a commercial locksmith and over 20 years in door hardware distribution.

Do-it-yourself guide.

Do-it-yourself guide.

Lock Cylinder Replacement

If all you need to do is change the key to your lock, and you are fairly good with tools, you may want to do it yourself. Or, you may want to remove the lock and bring it to a locksmith to be rekeyed. In rekeying, only tiny parts within the cylinder are changed; the rest of the lock stays the same.

Following is an overview of the various locks there are and how to change them.

Cylinders for Locks

In order to change your lock, you can replace your entire lock, or you can replace just the cylinder. Again, you can take just the cylinder to a locksmith to be rekeyed, also.

Three Basic Cylinder Types

  • Rim cylinders
  • Mortise cylinders
  • Cylindrical lock or tubular deadbolt cylinders

They are each pictured below.

Sargent Mortise Cylinder.

Sargent Mortise Cylinder.

Sargent Cylindrical Lock Cylinder.

Sargent Cylindrical Lock Cylinder.

Corbin Russwin 4200 Series Cylindrical Lock.

Corbin Russwin 4200 Series Cylindrical Lock.

Arrow Latch Face with brand name.

Arrow Latch Face with brand name.

Cylindrical Locks

Cylindrical locks are one of the most common types of locks, but they can be deceptively complicated to change. If this is the only lock on your apartment door, or if you want actual security, you might consider just leaving it alone and installing a deadbolt above it, since a cylindrical lock provides basically very little resistance to burglary.

Because of the great differences between cylindrical lock cylinders of different manufacturers and even between different product lines of the same manufacturer, it may not be feasible to purchase a replacement cylinder unless you know the exact make and model of the lock. If you do not have a replacement cylinder in advance, you will have to leave the secured space open while you fetch a new cylinder or get the existing one rekeyed, so plan to have someone watch the space while you are gone.

Many manufacturers offer their cylindrical lock installation instructions online. If you identify your cylindrical lock make and model you may be able to find these instructions online.

Above is shown a cylindrical key-in-knob lock. Below that is the latch face of a cylindrical lock, where you can usually find the brand name. Below this section is an illustration of a cylindrical key-in-lever lock.

  • To access the cylinder, you will need to remove the outside knob or lever. To do this, you will need a piece of stiff wire and the key to the lock. In the illustration below I have (rather crudely) indicated the location of the all-important poke hole. If you determine that your lock has no poke hole, that means that your lock is either cheap, old, or complicated to disassemble. Your best bet is to replace the whole lock.
  • If your lock indeed has a poke hole, to remove the outside knob or lever, insert the key and turn it 90 degrees. Depending on the lock function, this action may or may not retract the latch. With the key turned to 90 degrees, insert a piece of stiff wire or other slender, rigid object straight into the poke hole. Beneath the poke hole, there is a pin that must be depressed in order to allow the lever or knob to slide off. This process would be easy if you had three hands. To remove the knob or lever, you must pull on the knob or lever while depressing the pin beneath the poke hole and turning the key to the 90-degree position. It should slide off with a small amount of force.
  • Once you have removed the knob or lever, look inside from the back. The cylinder should be loose inside the knob or lever, or held in by a piece of plastic or sheet metal. Remove whatever is holding it in and remove the cylinder. Now look on the latch face (visible on the edge of the door) for the brand name of the lock. Armed with the brand name of the lock and the cylinder, you should be able to bring the cylinder to a locksmith and either purchase a replacement cylinder or have the locksmith rekey the cylinder as an over-the-counter transaction.
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Illustrated Cylindrical Lock.

Illustrated Cylindrical Lock.

Sargent Tubular Deadbolt.

Sargent Tubular Deadbolt.

Tubular Deadbolts

To avoid confusion, try to find installation instructions for your brand of deadbolt online. Like cylindrical locks, deadbolts often have their brand name stamped on the latch (or bolt) face (see picture of Arrow Latch Face above).

While tubular deadbolt cylinders can often be similar in appearance to cylindrical lock cylinders, they are usually much easier to get to. If the lock has a key on the outside and a thumbturn on the inside, simply unscrew screws until the lock comes off the door.

If the lock has a key inside and outside, the screws that hold the inside cylinder on are probably concealed. The usual way they are concealed is with drive-in covers, that is, screw covers that are tapped into place with a hammer. These screw covers are sometimes difficult to remove without damaging them. Some double-keyed deadbolts have a shutter that turns when the inside key is turned. When you turn the key to a certain degree, holes appear which allow the lock to be removed. Once the lock is removed, the cylinder will be clearly visible.

The outside cylinder will be held into the outside housing with a clip or screw, or it will actually be the outside housing.

As with the cylindrical lock, you can usually look on the edge of the door where the bolt projects and find the brand name of the lock. Armed with the brand name of the lock and the cylinder in hand, you can take your cylinder to a locksmith for rekeying or replacement.

When you are at the locksmith shop, ask if it would be cheaper to rekey the lock or to replace the entire lock with an equal lock. The locksmith will probably express an opinion about the quality of the lock. Based on that opinion, you can decide whether you might want to upgrade to a better lock.

When you reassemble the lock, note that the tailpiece, that is, the piece of metal that connects the cylinder(s) to the bolt, is (are) "timed". That means that they must be rotated so that the tailpiece is free to turn when the bolt is thrown by the turnknob or other cylinder. Such tailpieces are called "lazy" tailpieces because they are passive, allowing themselves to be turned by an outside force. You will know that you did it wrong if you reassemble the lock and then find that you cannot lock or unlock it from one side or the other.

Mortise Cylinder.

Mortise Cylinder.

Step 1.

Step 1.

Step 2.

Step 2.

Mortise Cylinders

Mortise cylinders are much easier to deal with than cylindrical lock cylinders or tubular deadbolt cylinders, but there are still a couple of things you need to know in order to get one in advance:

  • Cylinder length (dimension "X" in the illustration above)
  • Cam style (above)

The cam pictured above is specific to Sargent mortise locks. Different manufacturers use different cams for different models of mortise locks. If you have the wrong cam, your cylinder will probably not work right.

You can take the mortise cylinder with you to the locksmith shop and tell the counter person that you want one just like it. Of course, while your cylinder is out of the lock, your door is not secure.

A mortise cylinder is actually a big machine screw. It threads into the body of the mortise lock. It is kept from turning by a set screw.

How to Remove Mortise Cylinder From a Mortise Lock

  1. Remove the lock front, or faceplate, by removing the two faceplate screws as shown above.
  2. Loosen (but do not remove) the cylinder set screw (next picture down).
  3. Turn the mortise cylinder counter-clockwise until it comes out.

How to Install the New Mortise Cylinder

  1. Thread the mortise cylinder clockwise into the lock body.
  2. Tighten the cylinder set screw (be careful not to overtighten).
  3. Re-install the mortise lock faceplate.
Sargent Rim Cylinder.

Sargent Rim Cylinder.

Rim Cylinders

Rim Cylinders are the easiest of all cylinders to replace. For one thing, since there is very little difference between rim cylinders made by different manufacturers, you can just go buy one and it will probably work just fine.

How to Remove a Rim Cylinder

  1. Remove the lock from the door.
  2. Remove the two screws that hold the rim cylinder in place.

How to Install a New Rim Cylinder

  1. Cut the tailpiece if necessary with a bolt cutter or hacksaw.
  2. Fasten the rim cylinder screws through the cylinder backplate.
  3. Re-install rim lock.

Very easy. Cutting the tailpiece can be challenging if you've never done it before. Just be careful not to cut the tailpiece too short.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: Is it possible to change a mortise cylinder paddle lock (inside, key on the outside) with a thumb turn lock or deadbolt?

Answer: When you say "paddle lock," I think you probably mean an Adams Rite latch with a paddle inside and a cylinder outside. You can use a thumb turn mortise cylinder with this lock instead of the paddle. When you remove the paddle, there will be two mounting holes left visible.

If the faceplate of your Adams Rite latch is 6-7/8 inches tall, it can easily be replaced with an Adams Rite MS1850 deadbolt. You could use a thumb turn mortise cylinder with the MS1850, and you would still have the paddle mounting holes left exposed. The backset of the MS1850 (the distance between the centerline of the cylinder hole and the edge of the door) must be the same as the existing latch.

The strike, the part that receives the latch now, presents a bit of a problem in that there is no easy way to replace it with something that will receive the bolt. One would have to fabricate a custom metal plate to do the job. It would be difficult to make such a plate that would look anything but homemade. Getting the hole in the right place and the correct size to receive the bolt is a job for a professional.

Question: Which deadbolt is the most secure?

Answer: Every deadbolt has its strengths and weaknesses. In a cylindrical deadbolt, I like to see a good, strong, positively locking bolt, a cowl that protects the inner locking mechanism and a cylinder that offers at least some protection against picking and bumping. My recommendations would be the Medeco Maxum deadbolt, and the Schlage B660 in one of their Everest keyways. For a surface mounted deadbolt, I recommend the Segal 666 or 667 drop bolt. I have seen the Segal used with the Medeco Maxum on a hollow metal door resist attack pretty well.

The bottom line is always, however, that whatever can be put on with tools can be taken off with tools. All a good lock can really do is slow a burglar down. Burglars do not want to spend a lot of time breaking in. So, if you can make it difficult, they may either give up before getting in, or look for an easier door to break into.

© 2008 Tom rubenoff


Shaun W on August 23, 2019:

Hi Tom,

So I currently have older Kwikset locks (6 pin) that obviously have a KW keyway. This is for both my deadbolt and keyed entry lever. No "Smartkey" in them, thankfully. Now I'm looking at a smart home deadbolt, like Baldwin's (uses Kwikset's electronics, but their own locks), which use C keyways. Is there a way to insert a Baldwin C keyway cylinder lock (for one of their keyed entry knobs/levers) into a Kwikset keyed entry lever? I know the big issue is the tailpieces and getting them to play nice.

Tom rubenoff (author) from United States on September 08, 2018:

I'd say get it replaced. Many systems are tied in to the ignition. Best have the work done by an expert who specializes in car ignitions.

Selena Onstott on September 06, 2018:

If the tumbler locks on your ignition is broken do you have to replace it or not

Tom rubenoff (author) from United States on August 06, 2018:

There are several thousand combinations that are usable for a standard pin tumbler lock. It is certain in most cases that there are duplicates out there. So it is not surprising that your new key might open your old lock or vice versa. Your locksmith sounds good- your deadbolt situation doesn’t seem critical so may as well wait for now, maybe combine that repair with other service.

Best thing to do if you think you have unauthorized visitors would be to install video surveillance.

Nancy A. on August 06, 2018:

Question, our house was robbed. I've had the locksmith in 2016 to re-key all our locks and deadbolts in 2016. Yet we think someone has been back in our house. So frightening, especially as we have an alarm.

2 questions:

1. My husband installed a new door handle on our front door. We had not yet had it re-keyed to match all of the other locks. Accidentally, I inserted the new key to the door handle into the front door deadbolt which it unlocked. I freaked out. I checked and the new key did not unlock any of the other locks. I called the locksmith who came out. He said it was unusual but as there was a 7 on both keys, that was the reason the new key to the door handle unlocked the deadbolt he had previously re-keyed. Does that make sense? He re-keyed the door handle lock to match all the other locks.

2. The cylinder in the deadbolt on our kitchen door is loose. Also, you can push it in a bit from the inside, not from outside. I called the locksmith who said that was no big deal, something about a screw inside. Does that make sense?

I'm wondering if I need to get another locksmith in. This company gets very solid reviews and he is their senior locksmith.

Thank you in advance for your advice.

J Baldwin on November 25, 2017:

Thanks you so much. I had to change a lock tumbler and did not know about the push pin. Thanks again!!

Govinda on April 05, 2017:

Where can I get cylinders (to change the key) for NU-SET lock and Kwick ?

Tom rubenoff (author) from United States on June 22, 2016:

It is wonderful to know when my writing helps someone! Thanks for letting me know. Thank you.

Peter on June 20, 2016:

Thank you I am in Almeria Spain with a broken door lock, your very detailed information has enabled to repair my front door lock and secure my property once again. Thank You.