Ignition Lock Cylinder

The column-mount ignition lock cylinder uses 9 of the 10 key cut positions, 1-9 when counting from the key head. The tumbler orientations alternate in adjacent locations from side to side with 5 on one side and 4 on the other.

Fig 1: View Of Ignition Lock Cylinder Tumblers, Uncoded Cylinder Assembly, Tumbler Retainers, Tumbler Spring & Sidebar
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: The ignition lock cylinder tumblers (3) are not self-retaining and must be held in place if the key is not fully inserted into the lock cylinder or until the tumbler retainers (4) are properly staked into the cylinder.
1. Hold the uncoded cylinder assembly (1) positioned so the side with the retention lug is facing upward, spring-loaded retainer facing downward.
2. Insert one tumbler spring (2) each into the 3 tumbler spring holes.
3. The first tumbler to be loaded will be key cut position 1, the first number in the key code. Determine the cut depth at this position and install the corresponding tumbler (3) into the tumbler slot nearest the front of the cylinder assembly (1), the end where the key is inserted. It may be necessary to move the sidebar (5), already pre-assembled into the uncoded cylinder assembly, out slightly to fully install the tumbler into the correct tumbler slot.
4. In the same manner, determine the cut depth and corresponding tumbler and install the 4 remaining tumblers (3) into the tumbler slots located at key cut positions 3, 5, 7, and 9.
5. Check for correct loading by holding the tumblers (3) in position and fully inserting the matching key into the cylinder assembly (1). The sidebar (5) should be flush with the outside diameter of the cylinder assembly.
6. Rotate the cylinder assembly (1) so that the side with the retention lug is facing downward, spring-loaded retainer facing upward, and then remove the matching key. Remember the tumblers (3) are not self-retaining and must be held in place.
7. Insert one tumbler spring (2) each into the 4 tumbler spring holes.
8. The first tumbler to be loaded will be key cut position 2. Determine the cut depth at this position and install the corresponding tumbler (3) into the tumbler slot nearest the front of the cylinder assembly.
9. In the same manner, determine the cut depth and corresponding tumbler and install the 3 remaining tumblers (3) into the tumbler slots located at key cut positions 4, 6, and 8.
10. Check for correct loading by holding the tumblers (3) in position and fully inserting the matching key into the cylinder assembly (1). The sidebar (5) should be flush with the outside diameter of the cylinder assembly.
11. Lightly lubricate the tumbler (3) surfaces using the lubrication provided.
12. Load lubricated lock cylinder assembly into J 41340  and staking tool.
Fig 2: View Of Cylinder Assembly
Courtesy of GENERAL MOTORS CORP.
13. With the matching key fully inserted in the cylinder assembly (1), install and stake one tumbler retainer into recessed area on the cylinder. Stake the retainer in 4 places (6) making sure staked area is below flush with outside diameter of cylinder. Be careful not to damage the cylinder assembly while staking the tumbler retainer.
14. Rotate the cylinder assembly to the opposite side and repeat the procedure defined in step 13.