1. Support the aircraft in level flying attitude.

2. Chalkline the center-line of the aircraft onto the floor. Do this by connecting a mark on the floor from directly beneath the center of the firewall (use a plumb-bob) and from directly beneath the center of the tail (also using a plumb-bob).

3. Place a 36" straight edge against the outside of the tire. It should be parallel with the floor and approximately centered on the wheel.

4. Make a mark on the floor directly beneath each end of the 36" straight edge. Use a plumb-bob or square for this.

5. Measure and record distances D-1 and D-2. These are the distances between the marks in step 4 and the aircraft center-line.

6. Calculate ΔD, which is the difference between D-1 and D-2. ΔD changes by 0.157" for each ¼°.

To Change ΔD by 0.10" - 0.25" Use ¼° Shim
To Change ΔD by 0.25" - 0.40" Use ½° Shim
To Change ΔD by 0.40" - 0.55" Use ¾° Shim