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Speedo Gear Selection
When changing your ring and pinion set you will have to change your speedometer gear. The following is a listing of speedo gears when swapping gears using stock height tires and a stock T-5.
Stock T-5s in years 1990-1995 and 1996-1998 with the T-45 use a green 8 tooth trans drive gear. Here is the corresponding speedo gear for the axle ratio you have/ intend on installing.
3.08=20 tooth speedo gear
4.10= not available
If you have a T-5 Z-code super duty trans, a T-5 from 83-89, or a T-45 from a 96-98 Cobra you are using a 7 tooth yellow trans drive gear.
3.08=18 tooth speedo gear
If you have a different tire height than stock, use the following formula for the correct speedo gear.
Driven Gear Teeth= (Trans drive gear teeth X Tire revs per mile) / 1000
Written by: Chris Dyck