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General instructions for gearbox repairs > < Calculating the ?i? reduction ratio

Leon Mk1

Calculation of the gear ratio “i”
Calculation of the gear ratio “i”
The gear ratio is obtained by dividing the number of teeth on the driven gear by the number of teeth on the driving gear.
Example:
   
 5th gearDifferential
Driving sprocket (primary)45 (Z1 Primary)19 (Z1 Gear)
Driven sprocket (secondary)34 (Z2 Secondary)60 (Z2 Crown)

i = Z2 : Z1
In this way we can find out:
iG = Gear ratio of a gear
iG =
Z2 Secondary
Z1 Primary
=
34
45
= 0.756
iA = Gear ratio of the differential
iA =
Z2 Crown
Z1 Gear
=
60
19
= 3.158
itotal = Total gear ratio
Is obtained by multiplying the gear ratios of the longest gear and the differential.
itotal = iG x iA = 0.756 x 3.158 = 2.387
   

General instructions for gearbox repairs > < Calculating the ?i? reduction ratio