Introduction: How to Disassemble a Boda 4235 Lock Case (Abloy 4235)

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About: I'm not a professional. I try to learn as I do, and writing up my experiences seems to be useful to myself and hopefully to others as well.

I removed the central grey/steel U shaped detent piece but forgot to take a picture of it. The U detent is what holds the deadbolt locked and prevents bypass until the thumbturn/key is used. This mechanism consists of the U shaped detent piece and a small torsion spring which is mounted around the same pin the U detent pivots about. It is easily removed by holding onto the U detent and its spring and carefully pulling it upwards.

The latch and it's associated parts are quite simple, consisting of the following parts:

  • The latch itself
  • The latch detaining/return spring
  • The latch cam
  • The latch cam return spring

The latch itself is reversible depending on door orientation and is a brazed steel and brass part. The latch detaining/return spring is a torsion spring that holds the latch in place as well as holds it locked if nothing else is preventing this. The latch cam is roughly L shaped and has the requisite hole for the spindle. The return spring is a torsion spring (quite a beefy return spring to handle those 1980's big brass handles).

To remove the latch group start by lifting the latch cam and return spring out, there is no tension on the spring in this state, so they come out easily. Then carefully remove the torsion spring that detains the latch itself, this isn't very powerful, but if not handled carefully it will try to fly away. Once this is done, lift the inner end of the latch itself, and feed the whole part through the front of the lock case.

The latch group is now removed.

Supplies

Throughout this process you may need some tools. At least a screwdriver to open the case, maybe you will need pliers to handle some of the less friendly springs.

You will probably need something to clean the lock case and parts with, and some grease and oil to lubricate while reassembling.

Step 1: Disassembling a Boda 4235 Lockcase - Deadbolt

The deadbolt consists of the following parts:

  • The deadbolt itself
  • The deadbolt detaining/return spring
  • The deadbolt actuator group

The deadbolt itself is reversible depending on door orientation and is a brazed steel and brass part. The deadbolt detaining/return spring is a torsion spring that holds the latch in place as well as powers its locking motion and holds it locked if nothing else is preventing this. The deadbolt actuator group triggers the firing of the bolt and holds it unlocked. The deadbolt actuator group will be discussed later.

To remove the deadbolt group, carefully remove the torsion spring that detains the deadbolt itself, as with the latch spring, this isn't very powerful, but if not handled carefully it will try to fly away. Once this is done, lift the inner end of the latch itself, and feed the whole part out of the lock case.

The deadbolt group is now removed.

Step 2: Disassembling a Boda 4235 Lockcase - P Lever and Deadbolt Actuator

This section details the following parts:

  • The P lever
  • The deadbolt actuator/trigger

The P lever is used to retract both the latch and deadbolt when the thumbturn or key is used to open the locked door. This lever itself really belongs to the locking mechanism, however it is freely accessed now so will be removed now. It is called the P lever because it is shaped like a P, or a d or maybe a ? without the .

The deadbolt trigger is a small assembly of 3 parts. Their orientation is important to note as it is reversible depending on the orientation of the door. This applies to the latch and deadbolt also. The deadbolt trigger consists of (visible in the last picture of this step):

  • Wedge
  • Pin
  • Plate

The deadbolt trigger is held in place by a small but highly tensioned torsion spring, note its position before removing and note that the end of the spring in contact with the trigger sits in one of the grooves in the pin. Remove this, then carefully take out the trigger assembly through he back of the lock face. Make requisite notes of orientation and pull the assembly apart.

The P lever and deadbolt trigger are now removed.

Step 3: Disassembling a Boda 4235 Lockcase - Unlocking Mechanism

The unlocking assembly consists of:

  • The unlocking cam
  • 2 nylon spacers
  • 2 unlocking actuators
  • The transfer lever
  • (The P lever) - already removed

The unlocking cam is designed to transfer locking motion from the key or thumbturn via the unlocking actuators, to the transfer lever, to the P lever which in turn retracts the latch and deadbolt. This is an easy assembly to remove as it is not spring loaded (all return force is handled mainly by the latch and deadbolt springs). If these springs are weak you may get poor or lazy action when unlocking.

Removal of this assembly can be accomplished by first removing the the first nylon spacer and unlocking actuator. The unlocking cam can then be lifted out leaving behind the remaining nylon spacer and unlocking actuator. Remove these and the transfer lever.

The unlocking mechanism is now removed.

Step 4: Disassembling a Boda 4235 Lockcase - Mode Snib Group

The mode selection snib consists of:

  • The snib plate
  • The snib tactility spring
  • The plastic snib button

The purpose of this group is to select the locking mode. In the upper position the lock behaves as a deadbolt when the door is closed. In the lower position the deadbolt is disabled and the lock will only latch and be operable with the handle only.

When you wish to leave the door on latch only, you have to retract the deadbolt then switch the snib to the lower position. This pushes the snib plate down into the gap left by the retracted deadbolt. Release the deadbolt and it is no longer able to fully close and the lock is on latch only.

Removal is simple, the spring unwinds quite a lot but is very weak as its only purpose is to give minimal tactile resistance and aid in a decisive tactile click feeling when the snib is operated. Once the spring is removed, lift the snib plate off out of the lock case and away from the snib button. The snib button will then come out easily. Note that the snib button rides in a vertical groove in the snib plate.

That was a lot of snib. The snib group is now removed and the lock case is empty.

Step 5: Notes on Cleaning and Reassembling a Boda 4235 Lock Case

It makes sense to clean each part as you remove it, then place it on newspaper or paper towels in some sort of order to dry. Cleaning can be done with any cleaning solvent, alcohol be it ethanol along or denatured alcohol will do the job fine, as will white spirit and so on. Bear in mind there are plastic parts (three of them) that will not react too well to some solvents. Soapy water will be fine too, but may increase the amount of scrubbing you would have to do. I'd advise against putting parts in the dishwasher as dishwasher soap is quite harsh and the owner of the dishwasher may not approve.

Reassembly is the reverse of disassembly.

Use ample grease when reassembling, taking particular care to cover any part or surface that will see part against part motion. Pins and rotating parts should be greased well too. It may be a good idea to lightly dab some grease on the points of contact for springs and whatever it is they are contacting.

When placing parts back into place, pay attention to orientation and to the location of sliding parts in their respective guides. When placing the outer case back, go slow, make sure nothing is trapped, make sure all pins are in their guides and make sure that the latch cam and unlocking actuators are correctly placed in their circular guides.

That should be all. Thanks for reading.