94-95 Mustangs Drivetrain Speedometer Gears
From Mustang-Tech
Contents |
Overview
If your speedometer is off because of a change in your differential gears, there are a couple options to get it corrected.
The first and most popular option is to change the speedometer gear that is driven by the transmission. The amount of rotations on this gear is measured by the Vehicle Speed Sensor (VSS) and transformed into a signal the EEC can read.
In order to determine which gear you need, the formula is:
(number of drive shaft teeth * axle ratio * tire revs per mile) / 1000
So for example, if the drive shaft has a 8 tooth gear, and you have 3.73 gears, and your wheels turn 780 times per mile (typical for 18x9 rims with 285/35/18 tires), then you would get:
(8 * 3.73 * 710.07) / 1000 = 23.277
So you would need a 23 tooth speedometer gear. Use the tables bleow to determine which one is correct for your application.
The second option is to purchase a speedometer calibration box such as the Dallas Mustang SpeedCal. This box plugs inline to the VSS and can be configured to output a corrected signal for any number of combinations of gears and tire sizes.
Pictures
 Speedometer Gear |
Speedometer Gear Table[1]
Manual Transmissions with 6 Tooth Drive Gear
Found in
- Not found in OEM applications
| Item Number | Gear Ratio | Description |
|---|---|---|
| 3.08 Gear Ratio | Not possible | |
| C0DZ-17271-A | 3.27 Gear Ratio | Maroon 16 Speedo Gear |
| C3DZ-17271-C | 3.55 Gear Ratio | White 17 Speedo Gear |
| C0DD-17271-B | 3.73 Gear Ratio | Yellow 18 Speedo Gear |
| C0DZ-17271-B | 3.90 Gear Ratio | Pink 19 Speedo Gear |
| C1DZ-17271-A | 4.10 Gear Ratio | Black 20 Speedo Gear |
| C4OZ-17271-A | 4.30 Gear Ratio | Red 21 Speedo Gear |
Manual Transmissions with 7 Tooth Drive Gear
Found In
- 1983-1989 T-5 OEM
- Pre 1993 T-5 Aftermarket
- 1996-1998 Cobra T-45 OEM
- All Tremec Transmissions
| Item Number | Gear Ratio | Description |
|---|---|---|
| C0DZ-17271-A | 2.73 Gear Ratio | Maroon 16 Speedo Gear |
| C0DD-17271-B | 3.08 Gear Ratio | Yellow 18 Speedo Gear |
| C0DZ-17271-B | 3.27 Gear Ratio | Pink 19 Speedo Gear |
| C1DZ-17271-A | 3.55 Gear Ratio | Black 20 Speedo Gear |
| C4OZ-17271-A | 3.73 Gear Ratio | Red 21 Speedo Gear |
| Jeep Part #j3167393 | 4.10 Gear Ratio | White 23 Speedo Gear |
Manual Transmissions with 8 Tooth Drive Gear
Found In
- 1990-1995 T-5 OEM
- 1996-1998 T-45 OEM Except Cobra
| Item Number | Gear Ratio | Description |
|---|---|---|
| C0DD-17271-B | 2.73 Gear Ratio | Yellow 18 Speedo Gear |
| C1DZ-17271-A | 3.08 Gear Ratio | Black 20 Speedo Gear |
| C4OZ-17271-A | 3.27 Gear Ratio | Red 21 Speedo Gear |
| Jeep Part #j3167393 | 3.55 Gear Ratio | White 23 Speedo Gear |
| Jeep Part #j3167393 | 3.73 Gear Ratio | White 23 Speedo Gear (Not 100% accurate. This combination will offer the best accuracy without changing the drive gear. Change drive gear to a 6 tooth for complete accuracy. See 6 tooth table.) |
| Jeep Part #j3167393 | 4.10 Gear Ratio | White 23 Speedo Gear (Not 100% accurate. This combination will offer the best accuracy without changing the drive gear. Change drive gear to a 6 tooth for complete accuracy. See 6 tooth table.) |
Automatic Transmissions with 7 Tooth Drive Gear
Found In
- 1983-1989 Automatic Transmissions
| Item Number | Gear Ratio | Description |
|---|---|---|
| D0AZ-17271-A | 2.73 Gear Ratio | Blue 16 Speedo Gear |
| C7AZ-17271-B | 3.08 Gear Ratio | Gray 18 Speedo Gear |
| C7VY-17271-A | 3.27 Gear Ratio | Tan 19 Speedo Gear |
| C8SZ-17271-B | 3.55 Gear Ratio | Orange 20 Speedo Gear |
| D0OZ-17271-B | 3.73 Gear Ratio | Purple 21 Speedo Gear |
| Jeep Part #j3167393 | 4.10 Gear Ratio | White 23 Speedo Gear |
Automatic Transmissions with 8 Tooth Drive Gear
Found In
- 1990-1998 Automatic Transmissions
- 2003 V6 4R70W Automatic
| Item Number | Gear Ratio | Description |
|---|---|---|
| C7AZ-17271-B | 2.73 Gear Ratio | Gray 18 Speedo Gear |
| C8SZ-17271-B | 3.08 Gear Ratio | Orange 20 Speedo Gear |
| D0OZ-17271-B | 3.27 Gear Ratio | Purple 21 Speedo Gear |
| Jeep Part #j3167393 | 3.55 Gear Ratio | White 23 Speedo Gear |
| Jeep Part #j3167393 | 3.73 Gear Ratio | White 23 Speedo Gear (Not 100% accurate.) |
| Jeep Part #j3167393 | 4.10 Gear Ratio | White 23 Speedo Gear (Not 100% accurate.) |
Speedometer Drive Gears [1]
Now if you really want to change the internal drive gear of your manual tranny you can match it according to the table below. Be aware that the 6 tooth will offer the most combos for numerically higher gear ratios and offer the greatest degree of accuracy. The 6 tooth gear selection table for a manual tranny is the first in the page.
Note: For 4R70W transmissions, this is machined into the output shaft, so this is not an option if you have a 4R70W.
| Item Number | Teeth | Description |
|---|---|---|
| E3ZZ-17285-B | 6 Tooth Internal Drive Gear | Black |
| E3ZZ-17285-A | 7 Tooth Internal Drive Gear | Yellow |
| F0ZZ-17285-A | 8 Tooth Internal Drive Gear | Green |
