A Technician's : Unlocking Cross-Brand Compatibility by Rekeying a Kwikset Smart Lock to Schlage Keys

In the world of smart home automation, we chase a dream of seamless integration. We envision a home that anticipates our needs, where systems communicate flawlessly in the background. Yet, for many homeowners, this elegant digital harmony crashes into a harsh, analog reality at the front door. The culprit? The humble key. You may have a state-of-the-art Z-Wave network, a smart lock like the Kwikset Home Connect 620 that talks to your Ring alarm, but you’re still shackled by what I call “keyway fragmentation.” Your front door uses one key, the back door another, and the shed a third, simply because the locks were made by different brands. This isn’t just an inconvenience; it’s a betrayal of the smart home promise.

One of the most common divides in North American households is between Kwikset and Schlage. Many homes, through renovations or piecemeal upgrades, end up with a mix of both. You invest in a new, feature-rich Kwikset smart lock, only to realize it cannot use the same key as the three other Schlage locks securing your property. The conventional wisdom has always been that you must choose a side. This article is about rejecting that false choice. It’s a guide to achieving what many consider impossible: making a Kwikset smart lock work with a Schlage key.

Understanding the Divide: KW1 vs. SC1 Keyways

Before we dive into the solution, it’s crucial to understand the problem’s root. The incompatibility between Kwikset and Schlage keys isn’t arbitrary; it stems from the physical design of the “keyway”—the shape of the slot you slide your key into. Kwikset predominantly uses the KW1 keyway, while Schlage uses the SC1 keyway.

Imagine them as the USB-A and USB-C of the lock world. They perform a similar function but have entirely different physical profiles. The SC1 key is taller and has a more rectangular cross-section, while the KW1 key is shorter and wider. The internal pins of the lock cylinder are precisely milled to correspond with their designated keyway. You simply cannot fit an SC1 key into a KW1 cylinder, and vice versa. This fundamental design difference is why, for decades, homeowners have been forced to live with separate keys for their Kwikset and Schlage hardware.

The Hidden Gateway: Kwikset’s SmartKey and Its Interchangeable Core

So, if these keys are fundamentally different, are we destined to carry both? Not necessarily. The genius—and the well-kept secret—of Kwikset’s ecosystem lies not in the key, but in the cylinder that accepts it. Specifically, their SmartKey Security technology.

Publicly, Kwikset markets SmartKey as a feature for easy rekeying. If you lose a key, you can render it useless and rekey the lock to a new Kwikset key in seconds. It’s a powerful security feature that protects against lock bumping, with the ANSI/BHMA awarding it a Grade 2 security certification for residential use. However, the underlying architecture of the SmartKey cylinder is its true marvel: it is a modular, self-contained unit. This means the core component that defines the keyway (the cylinder itself) can, with the right part, be physically removed and replaced.

This modularity is our gateway. Kwikset, quietly and without much fanfare, manufactures a version of their SmartKey cylinder that is compatible with the Schlage SC1 keyway. It’s a niche part, intended for locksmiths and builders working on large, specified projects. But for the determined DIYer, it’s the golden ticket.

The Solution in Hand: Sourcing the Kwikset SC1 SmartKey Cylinder

The specific component you need is the Kwikset SC1 Keyway SmartKey Cylinder. The most common part number for this is 85174 (often followed by a finish code, like 85174-003 for Polished Brass or a black finish to match Venetian Bronze).

This is not a part you’ll typically find on the shelf at a big-box hardware store. You’ll likely need to source it from a specialized online lock supplier or a professional locksmithing distributor. A quick search for “Kwikset 85174” or “SC1 SmartKey cylinder” will usually point you in the right direction. It’s a small investment, typically under $20, that unlocks immense value by consolidating your home’s entire keying system.

Disclaimer: This guide is for informational purposes. Proceed at your own risk. Incorrect installation may damage your lock, void your warranty, or compromise your security. If you are not comfortable with detailed mechanical work, consult a professional locksmith.

Step-by-Step Technical Guide: Performing the Cylinder Transplant

Let’s use the Kwikset Home Connect 620 as our example. The process is similar for most Kwikset deadbolts and handlesets featuring the SmartKey cylinder.

Tools Needed: * Phillips Head Screwdriver * The original Kwikset key that operates the lock * Your new SC1 SmartKey Cylinder * (Optional but recommended) A clean, well-lit workspace

Step 1: Remove the Interior Assembly
On the inside of your door, locate the two screws holding the interior assembly of the deadbolt. Unscrew them completely and carefully detach the interior assembly. The wire connecting it to the exterior keypad will still be attached, so let it hang gently or have a partner hold it.

Step 2: Detach the Exterior Keypad
With the interior assembly removed, you can now pull the exterior keypad assembly straight out from the outside of the door.

Step 3: Expose the Cylinder Tailpiece
Place the exterior assembly face down on your workspace. You will see the back of the cylinder. There is typically a mounting plate held on by two more screws. Remove these screws to expose the entire cylinder.

Step 4: Remove the Original KW1 Cylinder
This is the critical step. The cylinder is held in place by a C-clip or a similar retaining mechanism. Carefully remove this clip. Once the clip is off, the entire SmartKey cylinder unit can be slid out of the lock housing. Pay close attention to the orientation of the tailpiece and any associated components.

Step 5: Install the New SC1 Cylinder
Take your new SC1 SmartKey cylinder (P/N 85174). Ensure it is oriented correctly and slide it into the housing where the old cylinder was. It should fit perfectly. Secure it in place with the same C-clip or retaining mechanism you removed earlier. A professional locksmith would advise ensuring the clip is fully seated to prevent any wiggle, which could lead to premature wear.

Step 6: Reassemble the Lock
Reverse the process. Re-attach the mounting plate to the back of the exterior assembly. Feed the wire back through the door, place the exterior keypad, and then re-attach the interior assembly with its two long screws. Do not overtighten; ensure the deadbolt mechanism can move smoothly without binding.

The Final Step: Re-Keying to Your Existing Schlage Key

Now for the magic. Your Kwikset lock is physically ready, but it’s still keyed to the new Kwikset-style key that came with the SC1 cylinder. You will now use the standard SmartKey rekeying procedure to match it to your existing Schlage key.

1. Insert the provided tool key: Take the key that came with your new SC1 cylinder, insert it into the lock, and turn it 90 degrees clockwise (horizontal).
2. Insert the SmartKey tool: While holding the key, insert the SmartKey “learn” tool fully and firmly into the small hole next to the keyway. You will feel a click. Remove the tool.
3. Remove the old key: Remove the original key.
4. Insert your Schlage key: Take your everyday Schlage key that operates the other locks in your house. Fully insert it into the cylinder.
5. Finalize: Rotate the Schlage key 180 degrees counter-clockwise. It should turn smoothly. Then, rotate it back to the starting vertical position and remove it.

Your Kwikset smart lock is now rekeyed. It will no longer work with the old key but will operate perfectly with your existing Schlage key. Test it several times to ensure it locks and unlocks smoothly.

Conclusion: True Smart Home Integration - Beyond the App

With the turn of the SmartKey tool, the final barrier falls. Your new smart lock now answers to your old, trusted key. This isn’t just a technical fix; it’s a fundamental upgrade to your home’s philosophy of access. It proves that true integration isn’t just about apps and voice commands—it’s about making technology conform to our lives, not the other way around.

By performing this modification, you reclaim control from brand ecosystems and build a truly unified, convenient, and secure home. The Kwikset Home Connect 620, with its Z-Wave 700 radio and robust features, is an excellent piece of hardware. But with this small, inexpensive cylinder transplant, it transforms from a great product into a perfect, personalized solution. You’ve achieved the holy grail of home access: one key to rule them all, seamlessly blending the best of digital convenience with analog simplicity.