Era Replica Automobiles 427 ROADSTER, Assembly And Service Manual

Page: 15 / 165

SECTION A -PARTS NEEDED-
15
Before you install the speedometer driven gear, check that
its spiral meshes properly with the drive gear.
Transmissions have come through with both the LH and RH
drive gears. See page 15 for calculations and page 15 for
part numbers.
SPEEDOMETER DRIVE GEARS
Ford transmissions used a variety of drive gears. The Mustangs Unlimited catalog is a good reference. The gears are
illustrated and detail specifications listed.
Note! The Ford Top-Loader drive gear may come with right or left hand threads. The driven gear must match.
You can calculate the number of teeth on the speedometer drive gears ( part #s on page 26 ) using the formula:
(Dif. Ratio)
x
(Tire revs/mile)
x
(Teeth on drive gear)
= (Teeth on driven gear)
(Speedometer revolutions/mile)
A 295-50-15 tire rolls 760 revs per mile. Both the Stewart Warner and Smiths speedometers are usually geared at 1000
revolutions/mile.
Usually the Ford Top-Loader, T-5 use a 7 tooth driving gear requiring a LH driven gear . Teeth = (Dif.Ratio) x 5.3.
Usually the Tremec uses a 7 tooth driving gear requiring a RH driven gear . So: Teeth = (Dif.Ratio) x 5.3.
The Richmond Gear transmission uses an 8 tooth driving gear. So: Teeth = (Dif. Ratio) x 6.06. See page 14 for gear
selection.
DRIVEN GEAR SELECTION AND PART NUMBERS
Ford Top-loader, T-5 and Tremec Richmond Gear 5 Speed
Diff.
Ratio
App.
Teeth
Toploader/T-5
Left-hand
Tremec
Right-hand
Diff.
Ratio
App.
Teeth
Part Number
2.88:1 18 3987918 (Brown)
3.07:1 16 Orange tip Burgundy 3.07:1 19 3987919 (White)
17 C2DZ-17271G
(Purple tip) C3DZ-17271C
(White) 3.31:1 20
21
3987920 (Blue)
3987921 (Red)
3.31:1 18 C2DZ-17271K
(Green tip) C0DD-17271B
(Yellow) 3.54:1 22 3987922 (Gray)
3.54:1 19 C4DZ-17271A
Pink tip C0DZ-17271B
(Pink)
3.77:1 20 C2DZ-17271H
Blue tip
C1DZ-17271A
(Black)
C8SZ-17271A
(Orange)
Retainer for all C1DZ-17292A