Mul-T-Lock MT5+ Classic Pinning Technical Manual

Why this matters

The Mul-T-Lock MT5+ is one of the most demanding high-security cylinders to pin correctly. It uses a 5-pin telescopic stack (inner pin inside outer pin, both elevation-coded independently) plus an alpha-locking sidebar. A standard pinning approach fails the cylinder - the lock either binds, picks the moment a tension wrench touches it, or fails to lock the sidebar at the correct position. Locksmiths who rekey MT5+ cylinders the way they rekey Schlage produce a cylinder that opens with the new key on the bench but fails in the field after 50 cycles. This technical manual walks the correct disassembly, pin selection by bitting, and reassembly sequence specific to the MT5+ Classic platform.

Cylinder anatomy

The MT5+ cylinder body has five chambers, each containing:

• An outer driver pin (top pin) with anti-pick spool or serrated geometry
• A telescoping bottom pin pair: an outer sleeve (Pin A) and an inner pin (Pin B) that slides inside Pin A
• A sidebar with five code wafers (alpha bar)
• The keyway has a sidewinder profile - the key blade has two cuts: standard bitting cuts on the blade top, and the sidebar-driving code cuts on the blade flat

The MT5+ key carries two independent codes that must match for the cylinder to rotate: the elevation code (telescopic pin stack alignment to shear line) and the alpha code (key flat cuts aligning the sidebar wafers).

Tools required

• Mul-T-Lock authorized service kit MT5+ pin tray with sealed bins of all 8 elevation codes for Pin A and Pin B
• Mul-T-Lock plug follower 0.500 in diameter, longer than the standard Kwikset follower
• Pin tweezers, sub-1 mm tip
• Code-cutting machine calibrated for MT5+ key blanks (Silca Triax with MT5+ jaw OR a Mul-T-Lock dealer-supplied A6 cutter)
• Mul-T-Lock A6 key blank in the customer's keyway profile
• Light oil (Mul-T-Lock white grease in the service kit; do NOT use graphite)
• Bench vise with soft jaws

Disassembly sequence

1. Insert the working key, rotate to the disassembly position (typically 12 o'clock for KIK, varies by cylinder housing).
2. With the plug follower held at the rear face of the cylinder, push the plug forward and out, capturing the plug as it ejects. The follower must remain in contact with the rear of the plug to retain the top pins and springs in the cylinder body. ANY gap and the top pin assemblies fire upward and the springs scatter.
3. Set the plug aside upright on a pinning block with the keyway facing up. Do not invert the plug - the telescopic pin pairs are not captive in the plug chambers when the key is in.
4. With the key still in the plug, photograph or sketch the visible elevation pattern at the shear line. This is your reference for the pin codes you just removed.
5. Remove the key. The bottom pins (Pin A sleeve and Pin B inner) drop free into the pinning block bins.

The alpha sidebar wafers stay in the plug body in their carrier - they do not need to be removed for a standard rekey unless the customer is changing the sidebar code (rare - requires a Mul-T-Lock dealer authorization).

Pin selection

The MT5+ has 8 elevation codes (1 through 8) for both Pin A and Pin B. The combined Pin A + Pin B stack height at each chamber must equal the standard system height minus the cut depth at that chamber on the new key.

For each chamber, determine the new key's elevation cut depth (read it off the cutter or measure with a depth gauge). Look up the Pin A and Pin B combination in the Mul-T-Lock pinning chart that produces that net height. Mul-T-Lock publishes the chart in the dealer manual; do not improvise.

The Pin A sleeve must always be longer than the Pin B inner pin for that chamber. Inverting them locks the cylinder at the next half-rotation. The chart respects this - do not deviate.

Anti-pick top pins: MT5+ top pins ship with serrated geometry. Reuse the top pins that came out of the cylinder unless they show visible wear at the shear-line contact ring. New top pins from the service kit if needed - do NOT substitute standard Mul-T-Lock top pins from older Interactive+ stock. The MT5+ uses a slightly different top-pin profile.

Reassembly

1. Place each Pin B inner pin into its plug chamber with the correct orientation (the conical tip faces upward toward the shear line).
2. Place the Pin A outer sleeve over the corresponding Pin B in the same chamber.
3. Insert the new key from the front. Both Pin A and Pin B should rise together to the shear line. Visually confirm at each chamber that the Pin A top edge is at or near the shear line, NOT sticking above (the cylinder will not turn) and not below (the cylinder picks at the slightest tension).
4. Verify the alpha sidebar by gentle rotation pressure. If the sidebar wafers do not retract, the key was not cut with the alpha code - check the cutter setup, do NOT force.
5. Slide the plug into the cylinder body from the front, displacing the follower as the plug enters. Watch the rear of the cylinder for top pins falling out - if any do, the chamber alignment is off and the plug needs to come back out.
6. Once the plug is fully seated, rotate slowly with the key 360 degrees. The rotation should feel smooth, with the sidebar engaging-disengaging twice per rotation. Any binding means a wrong-coded pin is in a chamber.

Verification

Cycle the cylinder 25 times with the new key. The action should feel consistent. Try the old key (if any) - it should NOT enter or turn. Try a key cut to a slightly different elevation (1 step shallower at any single chamber) - it should NOT turn. This confirms the elevation code is properly enforced.

For master-keyed installations, the master pin protocol is different from Schlage. Master pinning in MT5+ uses the alpha sidebar to differentiate change keys from masters - DO NOT add master wafers to the elevation stack. Adding elevation-stack master pins to an MT5+ creates picking vulnerabilities and the cylinder loses its high-security certification. Master keying MT5+ requires the dealer to ship a pre-coded sidebar specific to the master system.

Lubrication and final assembly

Apply a single drop of Mul-T-Lock white grease at each chamber's shear line through the keyway with a precision oiler. Do not graphite the cylinder - graphite contaminates the alpha sidebar wafers and causes intermittent sidebar non-engagement.

If installing in a mortise housing or knob, torque the cylinder retainer screw to the housing manufacturer's spec (typically 8 to 12 in-lb). Over-torquing distorts the cylinder body and binds the plug.

Documentation

Update the customer's key control register with:

• New key bitting (elevation and alpha codes)
• Cylinder serial (laser-etched on the cylinder body)
• Date of rekey
• Technician initials
• Old key disposition (returned to customer, destroyed, or kept in escrow)

Mul-T-Lock dealer agreements typically require all bitting records to be retained in the dealer's secure system AND with the customer's facility manager.

References

• ANSI/BHMA A156.30 Standard for High Security Cylinders for Doors
• ANSI/BHMA A156.5 Standard for Cylinders for Bored and Preassembled Locks
• UL 437 Standard for Key Locks
• Mul-T-Lock MT5+ Technical Manual current dealer edition
• Mul-T-Lock Pinning Chart MT5+ Classic Platform
• Mul-T-Lock Authorized Dealer Manual, Master Key Systems chapter