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Step-by-step Instructions For Replacing The Lock Cylinder: Tools And Stages Of Work, Advice And Recommendations From Specialists
Step-by-step Instructions For Replacing The Lock Cylinder: Tools And Stages Of Work, Advice And Recommendations From Specialists

Video: Step-by-step Instructions For Replacing The Lock Cylinder: Tools And Stages Of Work, Advice And Recommendations From Specialists

Video: How to Code a New Vehicle Ignition Lock Cylinder (Step by Step Guide!) 2022, December

Do-it-yourself lock cylinder replacement

Replacing the lock cylinder
Replacing the lock cylinder

Timely replacement of the larva will help prevent damage to the lock. It is this mechanism that is responsible for controlling the lock, identifies the key, opens access to the rotary mechanism, which moves the locking tab. In addition to rare cases of breakage of the key springs, the larva is in the first place in terms of wear - after all, it is used most often, several times a day.


  • 1 When to change the larva
  • 2 Types of castle larvae

    • 2.1 How to choose a new lock cylinder

      2.1.1 Video: how to choose a larva for the castle

  • 3 What malfunctions of the larva can be repaired without replacement
  • 4 How to replace the lock cylinder in the door

    • 4.1 Required tools for replacing and repairing the lock cylinder
    • 4.2 Dismantling the old lock cylinder
    • 4.3 Replacing the cylinder in a cylindrical mortise lock with overlay handles

      4.3.1 Video: Replacing the cylinder in the mortise lock

    • 4.4 Replacing the cylinder in a cylindrical mortise lock without handles
    • 4.5 Replacing the padlock cylinder

      4.5.1 Video: patch lock repair

    • 4.6 Replacing the cylinder with a cross key
  • 5 Care of the lock cylinder (expert advice)
  • 6 Reviews

When to change the larva

The larva is a combination lock mechanism used to identify the key. Locking mechanisms of all locks are arranged in approximately the same way, the only difference is in the "secret", which determines which key is suitable and which is not. Thanks to this device, secrecy is ensured: the door is opened only with a key that is at the disposal of the owners of the house or apartment.

The lock
The lock

The uniqueness of each larva lies in the set of pins located inside the cylinder

As a rule, locks last a very long time. But there are exceptions to all rules. Sometimes, for one reason or another, the mechanism fails, the process of closing or unlocking is difficult. The key does not turn, sticks, jams. Or vice versa - it rotates easily, but the lock tongue does not move. There are times when the key cannot be inserted into the well, and sometimes, on the contrary, it is impossible to get it from there. The reasons for this behavior of the castle are different:

  • natural breakdown of the mechanism due to wear of parts;
  • directional impact from the outside, mechanical damage, shock;
  • attempts to open the door with another key or without a key at all;
  • breaking into;
  • clogging of the keyhole with foreign objects, debris, rust.

In all these cases, immediate replacement of the larva is necessary. If you do not do this in a timely manner, one day you may find yourself in front of the door to your own apartment, which is impossible to enter.

To restore the work of the castle, in the vast majority of cases, it is not necessary to change it entirely. It is enough to purchase a new larva with a set of keys and install it in place of the old one. This work is easy to do on your own using simple tools. But sometimes it is better to turn to professionals, below we will consider such cases in more detail.

Types of castle larvae

"Sekretki" on locks of various designs have different shapes and devices. Therefore, first of all, you need to determine the type of lock. Here is a list of the most common and common types of locks.

  1. Cylinder. A very popular type of locking device. It is difficult to break into, which is important for ensuring the safety of property. Experts distinguish several types of cylinder locks:

    • key-key;
    • spinner key;

      Larva with lamb
      Larva with lamb

      A spinner on the inside of the lock allows you to open the door without using a key

    • gear;
    • half-cylinder.
  2. Disk. The rotary discs play the role of the identifying device when unlocking. It is rather difficult to find a related cylinder. Most often, the larva in such locks cannot be replaced. Completely change the castle.

    Disc door lock
    Disc door lock

    The disc lock is quite simple, but efficiency does not suffer from this

  3. Pin. Rare but still existing locking mechanisms of the English system. It is believed that pin locks are inferior to cylinder locks in terms of reliability. However, perforated systems are used quite successfully.
  4. Cruciform. Not the most secure type of lock. Experienced burglars open it with a Phillips screwdriver of the right size. Nevertheless, at the end of the last century, this type of locking device was very popular. Many still serve today. It is rather difficult to change the larva in such a castle. To do this, you must completely disassemble its body. Most often, in the event of an emergency situation, the lock is completely changed.

    Cross-shaped door lock
    Cross-shaped door lock

    In order to get to the lock cylinder with a cross-shaped key, you need to remove the mechanism from the doors and open the protective case

  5. Complex locks. This group includes devices with a special degree of protection. As a rule, their maintenance is carried out by the specialists of the manufacturers. Therefore, it is more advisable to entrust the replacement of larvae and secrets, of which there may be several, to professionals.

It is also pertinent to note that according to the type of fastening, locks are classified into mortise, hinged and overhead. This must be taken into account when choosing a new larva, since the attachment is different for everyone. Padlocks cannot be disassembled, replacement of the larva is possible only in a workshop. Most mortise locks for domestic use are designed in such a way that access to the larva is possible without disassembling the case. In overhead structures, for replacement, it is necessary to remove the lock from the door.

How to choose a new lock cylinder

The best way to find a new "secret" is to unscrew the old one and purchase an exact copy of it in the store. If the lock is made by a large industrial company, then it must be marked on it. Sales personnel are usually well versed in the pictograms and symbols that represent the product number. Consultants or managers will help you find an identical or compatible bot for any lock.

If there is no opportunity to take the "secret" to the store, you need:

  1. Remove the larva from the castle, photograph in several projections and put in place.
  2. Measure the length, thickness, and distance to the pusher tongue from the edges of the device. Another "floating" parameter is the location of the fixing hole. If the threaded hole is in the wrong place, the cylinder cannot be properly fixed.

    The main dimensions of the larva for the castle
    The main dimensions of the larva for the castle

    If you can't take the larva with you, you need to photograph it in all projections and write down all the main dimensions, including the distance to the hole for the clamping bolt

In addition to the size, when choosing, the material and color of the larva are taken into account. Copper or steel cores last much longer than brass or duralumin cores, but they are, of course, more expensive. The color is matched to the overall range of interior solutions.

According to the author, the best option is a core made of stainless steel. This material has practically no restrictions on the duration of operation, looks great on doors and withstands burglary attempts very well. The price of an iron cylinder is lower than that of a copper one, and the surface coating (nickel or chromium) protects the mechanism from corrosion.

Video: how to choose a larva for a castle

What malfunctions of the larva can be repaired without replacement

From time to time (at least once a year) the larva needs to be cleaned and oiled. This will protect it from malfunctions. Liquid grease (type VD-40) not only rinses the working cavity, but also lubricates the rubbing parts - pins and pins. But after such "washing" it is recommended to additionally lubricate the larva with graphite grease.

Liquid grease VD-40
Liquid grease VD-40

Low viscosity multipurpose household grease is guaranteed to remove dry spots in the locking mechanism

If foreign objects get inside the larva - matches, paper clips, etc., they need to be removed and the larva is blown out with a vacuum cleaner. It is convenient to use a magnet to remove small metal objects.

The most unpleasant thing that can happen is getting into the keyhole of a solidifying liquid mixture - diluted cement, acrylic or silicone sealant, polyurethane foam or banal chewing gum. After solidification, these substances turn into a monolithic mass, which is almost impossible to extract. Previously, such "tricks" were used by hooligans, wanting to harm the residents. In such cases, the larva has to be changed. To protect the keyhole from ill-wishers, a screen is installed inside the core, which is fixed with a steel spring.

How to replace the lock cylinder in the door

Before starting work, you need to make sure you have the right tools.

Necessary tools for replacing and repairing the lock cylinder

To extract the secret from the lock case, you need to prepare simple tools in advance. They will surely be found in every home:

  • screwdriver;

    Phillips screwdriver
    Phillips screwdriver

    The screwdriver is matched to the shape and size of the fixing screws

  • tape measure or ruler, vernier caliper;


    It is more convenient and more accurate to measure the diameter of the cylindrical core using a vernier caliper

  • new larva;
  • oiler.

The screwdriver must be selected with slots identical to the fixing screw. Most often this is the PH2 cross. You can use a drill with attachments or a screwdriver, for example, furniture, with a low speed and high power. The cylinder retainer in the mortise lock is located at the end of the door leaf, on the lock bar. Measuring tools - tape measure, ruler or vernier caliper - are needed to determine the exact dimensions of the original larva. Theoretically, you can install a cylinder that is longer than the thickness of the door (but not more than 5 mm). However, it is believed that this increases the risk of penetration, since the part protruding from the outside can easily be broken or cut down and thus gain access to the pivot mechanism.

Dismantling the old lock cylinder

In order to remove the old larva, you must:

  1. Open the door.
  2. Unscrew the retaining screw at the end of the door leaf.

    Removing the mortise lock
    Removing the mortise lock

    The fixing screw is located in the middle of the locking strip

  3. Insert the key into the keyhole and align the swivel tab.
  4. Press the larva from the outside with your finger (until it falls out).

Replacing the larva in a cylindrical mortise lock with overlay handles

If the door lock kit includes handles with overlays, then before starting the repair it is necessary to loosen the screws of their fastening (4 pcs.) This will open access to the larva.

Removing the door handles
Removing the door handles

The use of a furniture screwdriver significantly speeds up the dismantling process

After removing the non-working core, a new one must be installed in the vacant place. To do this, a key is inserted into the larva and the cylinder is brought to such a position when the pusher tongue is immersed in the larva body. Then:

  1. The larva is installed in the opening of the lock. The position should be such that the fixing screw from the end of the door fits exactly into the hole in the core. Deviations are unacceptable, as they lead to a distortion of the pushing mechanism.
  2. The fixing bolt is screwed in until it stops.
  3. The work of the lock is checked. The key is turned several turns clockwise and in the opposite direction.
  4. The lock is assembled in the reverse order - lining and handles are attached.

    Replacing the larva with a lock with handles
    Replacing the larva with a lock with handles

    Remove door handles and decorative strips before replacing the core

If everything is working properly, we can assume that the repair is over. Before installing the core, it is recommended to lubricate its rotating parts - the cylinder and the pusher. Remove excess oil with a clean cloth.

Video: replacing the larva in the mortise lock

Replacing the larva in a cylindrical mortise lock without handles

If the cylinder door lock does not have handles, the procedure remains the same. However, there is no need to remove handles and covers. Access to the larva in such models is open, and dismantling begins directly with unscrewing the larva lock at the end of the door leaf.

Replacing the cylinder of the patch lock

The algorithm of actions for replacing the larva in the overhead lock is somewhat different compared to the mortise one.

  1. The four screws that attach the lock to the door leaf are unscrewed. The lock is removed from the door.

    Dismantling the padlock
    Dismantling the padlock

    The screws securing the patch lock can be of complex shape or with recesses for a hex key

  2. The rear cover of the lock is removed, for which the four screws that hold it are loosened.
  3. The larva is fixed with two screws that must be unscrewed in order to free the core.
  4. Reassembly. A new core is installed. The two fixing bolts are tightened.
  5. The back cover is closed. The four fixing bolts are tightened.
  6. The lock is mounted in its original place and attached to the door leaf.

    Attaching a patch lock
    Attaching a patch lock

    Fixing the body of the padlock is carried out with two screws at the end of the door leaf

In addition to four screws on the outer plane of the door, patch locks are sometimes attached with additional screws at the end of the door leaf. Check the operation of the lock before final tightening of all screws. To do this, the gear is scrolled both clockwise and counterclockwise. If the locking mechanism works correctly, the screws are tightened completely, with maximum effort.

Video: patch lock repair

Replacing the lock cylinder with a cross-shaped key

As mentioned above, cross key locks are gradually falling out of fashion and use. Partly because of this, the components for them are not always easy to get. Nevertheless, if necessary, you can try and replace the larva of such a lock. The order of work is as follows.

  1. The handles and covers are removed from the lock (if any). On the inside of the door, unscrew four fixing screws.
  2. On the front plate at the end of the door, two screws are released that hold the lock in the door leaf. The lock body is removed from the door.
  3. To remove the cover from the lock case, unscrew all the screws located outside the mechanism. There can be from four to eight.

    Disassembled cross key lock
    Disassembled cross key lock

    Four to eight screws can be used to secure the lock cover

  4. The cruciform larva is twisted. It is usually attached with two screws.
  5. In place of the damaged "lock" a new one is installed and fixed with two screws.

    Cylinder for lock with hex keys
    Cylinder for lock with hex keys

    The larva for hex keys usually has two holes for attaching to the lock body

  6. After checking the work, the lock is reassembled.

Care of the castle larva (expert advice)

For the castle to serve for a long time and without surprises, you need to pay a little attention to it at least once a year. First of all, this concerns the cleaning of the larva from pollution. Contact with the external environment: dust, moisture and temperature changes - all this affects the operation of the lock. Sooner or later, dirt builds up, and the lock can simply jam.

Door lock cylinder lubricant
Door lock cylinder lubricant

The wash for the lock is poured directly into the keyhole

Experts recommend periodically (depending on operating conditions) to flush the inner cavity of the larva. For this, there are special fluids that are easy to find in specialized stores and key workshops. The flushing procedure is quite simple:

  • a cleaning spray from a can is poured into the larva;
  • the key is inserted to the full depth;
  • the key is removed and cleaned of adhering dirt.

This operation is performed until the key is completely cleared. After prophylaxis from the inside of the door, the same is done outside.

If the lock on the front door is to be cleaned, it is advisable to select a flushing fluid with water-repellent and frost-resistant properties

After cleaning the lock from dust and dirt, the key is dipped in lubricant, inserted into the larva and turned in different directions. This allows oil to penetrate the core and lubricate the pins, springs and pins. Most often, machine (motor) or spindle oil is used as a lubricant. But it is better to use a special lubricant developed specifically for locks of this design. Remove excess grease with a cloth.


Replacing the larva in a simple lock takes a few minutes. In this case, there is no need for any settings or adjustments. In complex locks, which are installed on the front doors, the situation is different. Everything is so serious here that some manufacturing companies leave a duplicate key for safekeeping. It is better not to service or repair such doors yourself; the locks are equipped with all sorts of tricks and tricks.

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