--- title: How do I open my 8400 Series mechanical lock? description: If you have a Group 1 lock that must has a silver arrow in the center of your dial, these instructions will help. --- [Skip to content](https://resources.sargentandgreenleaf.com/migration/knowledge/how-do-i-open-my-8400-series-mechanical-lock#main-content) English Show submenu for translations [Get Support](https://resources.sargentandgreenleaf.com/migration/knowledge/kb-tickets/new?hsLang=en) [Customer portal](https://resources.sargentandgreenleaf.com/tickets-view?hsLang=en) ![sg\_logo\_horiz\_rgb\_trans.png\]](https://resources.sargentandgreenleaf.com/hs-fs/hubfs/SandG%20Logos/sg_logo_horiz_rgb_trans.png?height=40&name=sg_logo_horiz_rgb_trans.png) Open main navigation Close main navigation - English Show submenu for translations - [Get Support](https://resources.sargentandgreenleaf.com/migration/knowledge/kb-tickets/new) - [Customer portal](https://resources.sargentandgreenleaf.com/tickets-view) - Main site Main site Hello. How can we help you? - There are no suggestions because the search field is empty. 1. [Help Center](https://resources.sargentandgreenleaf.com/migration/knowledge?hsLang=en) 2. [Mechanical Spin Dial Locks](https://resources.sargentandgreenleaf.com/migration/knowledge/mechanical-spin-dial-locks?hsLang=en) 3. [8400-8500 Series](https://resources.sargentandgreenleaf.com/migration/knowledge/mechanical-spin-dial-locks?hsLang=en#8400-8500-series) # How do I open my 8400 Series mechanical lock? ## If you have a Group 1 lock that must has a silver arrow in the center of your dial, these instructions will help. **Important**: Turn dial slowly and evenly. Do not turn back to regain alignment if you rotate past number. If an error is made, re-dial entire combination. Do not count turns. Count how many times each number is aligned with the opening index (at the 12 o’clock position). Always view the dial and ring straight on, not at an angle. 1: Turn dial left, past 50 three times stopping on the fourth time you come to it. 2: Turn dial right, past 25 two times stopping on the third time you come to it. 3: Turn dial left, past 50 once stopping on the second time you come to it. 4: Turn dial right stopping at “0.” 5: With one hand hold the dial with “0” aligned with the opening index and use your other hand to turn the arrow knob 1/4 turn to the right (as far as it will go). 6: Turn the dial to the right until it stops. The bolt is now fully retracted. **To Lock**: Turn the dial to the left, stopping when 0 is aligned with the dialing index. Hold the dial at 0 and turn the arrow knob 1/4 turn to the left (as far as it will go). Turn the dial left at least 4 complete turns. **CAUTION:** Do not turn the Arrow Knob when dial is set at any position other than “0.”   - [Electronic Push Button Locks](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#main-content) - [A-Series™](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#a-series) - [Digital Time Lock](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#digital-time-lock) - [Model 6123](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#model-6123) - [Model 6124, 6125](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#model-6124-6125) - [Spartan™](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#spartan) - [Titan™](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#titan) - [Keypads](https://resources.sargentandgreenleaf.com/migration/knowledge/electronic-push-button-locks?hsLang=en#keypads) - [Mechanical Spin Dial Locks](https://resources.sargentandgreenleaf.com/migration/knowledge/mechanical-spin-dial-locks?hsLang=en#main-content) - [8400-8500 Series](https://resources.sargentandgreenleaf.com/migration/knowledge/mechanical-spin-dial-locks?hsLang=en#8400-8500-series) - [Model 2937](https://resources.sargentandgreenleaf.com/migration/knowledge/mechanical-spin-dial-locks?hsLang=en#model-2937) - [Model 6730, 6731, 6741](https://resources.sargentandgreenleaf.com/migration/knowledge/mechanical-spin-dial-locks?hsLang=en#model-6730-6731-6741) - [Padlocks](https://resources.sargentandgreenleaf.com/migration/knowledge/padlocks?hsLang=en#main-content) - [Model 8077](https://resources.sargentandgreenleaf.com/migration/knowledge/padlocks?hsLang=en#model-8077) - [ATM Locks](https://resources.sargentandgreenleaf.com/migration/knowledge/atm-locks?hsLang=en) - [Archive](https://resources.sargentandgreenleaf.com/migration/knowledge/archive?hsLang=en#main-content) - [2740A](https://resources.sargentandgreenleaf.com/migration/knowledge/archive?hsLang=en#2740a) - [Z02](https://resources.sargentandgreenleaf.com/migration/knowledge/archive?hsLang=en#z02) - [IP Lock](https://resources.sargentandgreenleaf.com/migration/knowledge/archive?hsLang=en#ip-lock) - [6300](https://resources.sargentandgreenleaf.com/migration/knowledge/archive?hsLang=en#6300) - [2890B](https://resources.sargentandgreenleaf.com/migration/knowledge/2890b?hsLang=en#main-content) - [2890B](https://resources.sargentandgreenleaf.com/migration/knowledge/2890b?hsLang=en#2890b) - [Audit Lock, Model 6126, Model 6127, Model 6128](https://resources.sargentandgreenleaf.com/migration/knowledge/audit-lock-model-6126-model-6127-model-6128?hsLang=en#main-content) - [Audit Lock, 6126, 6127, 6128](https://resources.sargentandgreenleaf.com/migration/knowledge/audit-lock-model-6126-model-6127-model-6128?hsLang=en#audit-lock-6126-6127-6128) - [All Locks](https://resources.sargentandgreenleaf.com/migration/knowledge/all-locks?hsLang=en) - [2740B](https://resources.sargentandgreenleaf.com/migration/knowledge/2740b?hsLang=en) [![Chill listening crop-3](https://resources.sargentandgreenleaf.com/hs-fs/hubfs/SandG%20Logos/sg_logo_horiz_rgb_trans.png?width=88&height=32&name=sg_logo_horiz_rgb_trans.png "Chill listening crop-3")](http://www.sargentandgreenleaf.com?hsLang=en) Sargent and Greenleaf Help Center Copyright © 2026, Sargent and Greenleaf