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Locksmithing/kwik set deadbolt lock



i have a brand new kwikset deadbolt  am installing it but not quite succeeding

1. i do not know the difference between one cylinder and two cylinders  it looks like one cylinder

2. i put in the dead bolt assembly through the side opening  up is on top

3. put together the two conical assemblies  put one in from the outside,  aligned the small extension into the opening in the center of the deadbolt

4. came to inside  inserted the small extension into the extension from the outside one  of course both are then contained in the main dead bolt opening

5. before putting in the long tightening screws  tried the deadbolt opening / closing      from inside it works     tried from outside, no movement

also having difficulty matching the two tightening long screws, but i guess if i can get the closing/opening correct, the screws can be done

thank you very much

ANSWER: Hello Aamir,

One cylinder, referred to as single cylinder is when the lock is operated by a key from one side.

Two cylinder, referred to as double cylinder is when the lock is operated by a key from both sides.

Kwikset locks are generally simple to install.  Their deadbolts have a D shaped tailpiece - the small extensions you referred to. They only fit into the hole in the bolt mechanism one way, even those that are double cylinder models.

It is possible that you may have a slightly different tailpiece and this is the best way to make sure you are installing almost any deadbolt properly:

1. Install the bolt mechanism making sure that if the hole for the tailpiece is not centered that it's on the bottom.
2. With the door open, extend the bolt so it's in the locked position.
3. Face the edge of the door, again with it open.
4. Place the outside lock assembly into the palm of your hand with the keyed side facing your palm and the top of the lock closest to your thumb.
5. Turn the tailpiece towards the hinges of your door until it stops - if the lock is in your right hand, turn it counter-clockwise; left hand, turn clockwise.
6. Install the assembly, making sure the tailepiece goes into the hole of the bolt mechanism.
7. If you have a double cylinder lock, repeat steps 4 to 6,
8. If you have a single cylinder deadbolt, slide the thumbturn assembly onto the tailpiece on the opposite side of the door.
9. With the mounting holes at the 9 and 3 o'clock positions, insert the mounting screws one at a time, moving the outside assembly until you can feel the screw start into the proper place then turn it by hand a few times.  Repeat for the other screw.
10. Tighten the screws down but do not over tighten.  You'll know if they are too tight if you can't turn the key or thumbuturn easily.

If the key and thumbturn operate it correctly, shut the door and make sure it locks and unlocks smoothly.

It's hard to explain in words but I hope this helps.


---------- FOLLOW-UP ----------

QUESTION: thank you for your detailed note   a couple of things remain:

why did i have the problem i described in the first place? THE DEADBOLT WAS ONLY OPERATIONAL FROM ONE SIDE

what is the tailpiece  i did not understand is not centered that its on the bottom

turn what counterclockwise?

since we have a key location on either side i assume that this is a double arrangement   what is the thumbturn

don't i have to put the small extensions both into the hole in the deadbolt  after both being inside, does not one have to go into the other to establish the drive

The most difficult part has been to ensure that both the extensions are in the big hole and also one into the other. when it seems that this is OK AND YOU WANT TO START THE FIRST OF THE TWO LONG SCREwS EVERYTHING FALLS APART


ignore the capitals as being normal

Hello again Aamir,

It's difficult to know why you had the issue but it's best to get everything installed before you try to operate it.

The tailpiece is the part that extends out from the back of each side of the housings of your lock - the part that slides into the center of the deadbolt, as you put it.  It's what operates the bolt when the key is turned.

When I mentioned 'bottom' I'm referring to the bolt mechanism and the hole that the tailpiece goes in to.

Turn the tailpiece clockwise.

You don't have a thumbturn so ignore this step.

The extensions are tailpieces and on the double cylinder models one goes into the other when installed.

It's quite possible that your door is too thick for this lock.  Anything over 1-3/4" thick is difficult if not impossible to install a double cylinder deadbolt because the tailpieces are too short.

Your first issue might be cause by the outside tailpiece slipping out of the inside one as you are installing this. If the tailpiece isn't inserted fully it will slip out and not function.

Your screws might be too short as well if your door is too thick.

I'd highly recommend reviewing the instructions that should have come with the lock before you try again.

Try this link if you have no instructions:



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I do not answer Safe or automotive questions. Period. I am knowledgeable in almost every area of Locksmithing. This includes locks, keys, lost keys, residential and commercial lockouts, rekeying, masterkeying, high security locks, access control, electric locks, security cameras and home safety. I have been running an online business since 2004 where I sell all types of lock and security hardware to everyone from apartment renters to business owners to the US government. Before that I started a locksmith service in 1999. I deal with many types of security equipment including high security safe locks, heavy duty padlocks, exit devices, biometric readers, electric strikes, magnetic locks, full surface hinges and I only sell what I personally stand behind 100%. The online business has given me a more in-depth look at the locksmithing industry, helping me to learn more about each and every product that I offer, as well as products I don't have but end up finding for customers to solve any issues they have with security or door hardware.

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