Mortise Cylinder Measurement & Sizing Guide
Shop Replacement Mortise Cylinders
Use this guide to identify and measure an American-style mortise cylinder, match the cam, and choose the correct finish before ordering.
- Watch: Ordering and Installing a Mortise Cylinder
- Print the Mortise Cylinder Measurement and Ordering Guide at 100% Scale
Replace the Cylinder, Not Necessarily the Entire Lock
If the mortise lock mechanism and decorative trim still work, you can often replace only the keyed cylinder. Confirm the cylinder length, cam, keyway, and finish before ordering.
How to Order the Correct Mortise Cylinder
- Measure the length. Measure from the underside of the front flange to the back edge of the cylinder body. Do not include the cam.
- Match the cam. Compare the cam on the back of the old cylinder with the available Baldwin pear-shaped and Accurate clover-shaped options.
- Choose the finish. Select the finish that best coordinates with the existing trim.
Choose Your Length, Cam, and Finish
Mortise Cylinder Questions
How do I know whether I have a mortise cylinder?
A mortise cylinder has threaded sides and a short rotating cam on the back. A rim cylinder has smooth sides, two long mounting screws, and a long tailpiece; a tubular or cylindrical lock normally has a small latch faceplate and does not use this cylinder.
Does door thickness determine the cylinder length?
Not by itself. The correct length also depends on the thickness of the rose or escutcheon surrounding the cylinder, so measure the existing cylinder rather than ordering from door thickness alone.
Which cam do I need?
Match the cam on the replacement cylinder to the cam on the existing cylinder. The wrong cam may thread into the lock but fail to operate it.
What is a Schlage C 5-pin keyway?
Schlage C is a widely used residential keyway with commonly available replacement key blanks. A locksmith can generally rekey this cylinder to an existing Schlage or Schlage-compatible key.
Will this fit Baldwin, Emtek, or other designer hardware?
This American-style cylinder uses the standard mortise-cylinder thread found in many Baldwin, Emtek, Rocky Mountain Hardware, Sun Valley Bronze, Classic Brass, and Accurate locks. Brand alone does not confirm compatibility; verify the length and cam before ordering.
Why will the cylinder not screw into the lock?
The retaining set screw on the door edge may still be pressing against the cylinder threads. Back it out enough to release the cylinder, align the threads carefully, and never force the cylinder.
Why is the key difficult to turn after installation?
The retaining set screw may be overtightened, or the cam or cylinder depth may be incorrect. Loosen the set screw slightly and test the key again without forcing it.
How far should I screw the cylinder into the lock?
Thread it in until the face sits properly against the rose or escutcheon without projecting too far or sitting too deeply, then secure it with the retaining set screw.
Still uncertain? Send Classic Door clear photographs of the existing cylinder and cam with your measurements before ordering.