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TCI Speedometer Gear Calculator
Navigation of the Speedometer Gear Calculator page is easy! Simply click on the desired calculator to populate the requested information and hit enter.
Formula for Calculating Speedometer Gears
The following formula will work for any GM, Ford or Chrysler vehicle and is very useful when there is no established baseline from which to work from such as replacing a transmission in a vehicle that was purchased without a drive line. The accompanying charts show what gears were manufactured for each type transmission. TCI® now stocks the most popular speedometer gears.
PLEASE NOTE: Drive gear refers to the gear that is on the transmission output shaft. The driven gear is located in a removable housing usually in the tailhousing of the transmission. Be aware that some transmissions will have different driven gear housings depending on the tooth count of the driven gear.
| ##Drive Teeth# X Axle Ratio X Tire Rev. per Mile | = # Driven Teeth |
| 1001 |
Use the following formula to calculate the Tire Rev. per Mile for the above formula.
| Tire Rev. per Mile = | #.20168. |
| Tire Diameter (inches) |
Speedometer Gear Calculator
Try this handy custom calculator. It will do all the work for you. If you dont know your tire diameter, calculate it below using the P-metric sidewall designation.
Speedometer Gear Charts
Speedometer gears: 2004R | TH350 | TH400 | 700R4 | Torqueflite | Ford
GM SPEEDOMETER GEAR INFORMATION
2004R Speedometer Gears
| Drive Gears | Driven Gears |
| 10 teeth - green | 26 teeth - brown |
| 11 teeth - orange* | 27 teeth - black |
| 12 teeth - red | 28 teeth - yellow |
| 13 teeth - white | 29 teeth - green |
| 30 teeth - blue | |
| 31 teeth - white |
NOTES:
| All 2004R transmissions use a 1" diameter steel driven gear housing. |
| The drive gear is part of the governor assembly which is located inside the oil pan. The gear can be replaced separately by removing the retainer clip on the governor shaft. |
PLEASE NOTE: This gear is shipped in all TCI® StreetFighter® 2004R transmissions (Original to Buick Turbo Regal applications).
TH350 Speedometer Gears
| Drive Gears | Driven Gears |
| 7 teeth - pink | 18 teeth - brown |
| 8 teeth - black | 19 teeth - natural |
| 9 teeth - green | 20 teeth - blue |
| 10 teeth - red or purple | 21 teeth - red |
| 17 teeth - red | 22 teeth - gray |
| 18 teeth - blue | 34 teeth - light green |
| 19 teeth - yellow | 35 teeth - orange/pink |
| 20 teeth - brown | 36 teeth - white |
| 37 teeth - red | |
| 38 teeth - blue | |
| 39 teeth - brown | |
| 40 teeth - black | |
| 41 teeth - yellow | |
| 42 teeth - green | |
| 43 teeth - purple | |
| 44 teeth - dark gray | |
| 45 teeth - light blue |
NOTES:
| Chevrolet transmissions use a 1" diameter steel driven gear housing located in the tailhousing on all two-wheel drive applications. |
| Buick, Oldsmobile & Pontiac transmissions use a 2.078" diameter driven gear housing. Two housings, each made from either aluminum or plastic, are available for driven gears with 34 or more teeth. One fits gears from 34 - 39 teeth and the second one fits gears from 40 - 45 teeth. |
TH400 Speedometer Gears
| Drive Gears | Driven Gears |
| 7 teeth - red | 16 teeth - (truck) |
| 8 teeth - black | 17 teeth - (truck) |
| 15 teeth - brown or gray* | 18 teeth - (truck) code H |
| 16 teeth - orange | 19 teeth - (truck) code J |
| 17 teeth - red | 20 teeth - (truck) code K |
| 18 teeth - yellow or blue | 21 teeth - (truck) code L |
| 19 teeth - yellow or white | 22 teeth - (truck) code M |
| 20 teeth - green | 34 teeth - light green |
| 21 teeth - black | 35 teeth - pink |
| 36 teeth - white | |
| 37 teeth - red | |
| 38 teeth - blue | |
| 39 teeth - brown | |
| 40 teeth - black | |
| 41 teeth - yellow | |
| 42 teeth - green | |
| 43 teeth - purple | |
| 44 teeth - dark gray | |
| 45 teeth - light blue |
NOTES:
| Two aluminum housings are available for driven gears with 34 or more teeth. One fits gears from 34 - 39 teeth and the second one fits gears from 40 - 45 teeth. |
| The driven gear housings go in the case just forward of the tailhousing. |
PLEASE NOTE: This gear is shipped in all TCI® StreetFighter® TH400 transmissions.
700R4 Speedometer Gears
| Drive Gears | Driven Gears |
| 15 teeth - gray | 18 teeth - (truck) brown |
| 17 teeth - red* | 19 teeth - (truck) dark aqua |
| 18 teeth - blue | 20 teeth - (truck) silver |
| 19 teeth - yellow | 21 teeth - (truck) red/chartreuse |
| 20 teeth - brown | 22 teeth - (truck) gold |
| 23 teeth - (truck) maroon | |
| 24 teeth - (truck) dark blue | |
| 34 teeth - light green | |
| 35 teeth - orange/pink | |
| 36 teeth - white | |
| 37 teeth - red | |
| 38 teeth - blue | |
| 39 teeth - brown | |
| 40 teeth - black | |
| 41 teeth - yellow | |
| 42 teeth - green | |
| 43 teeth - purple | |
| 44 teeth - dark gray | |
| 45 teeth - light blue |
PLEASE NOTE: This gear is shipped in all TCI Street Fighter 700-R4 transmissions.
NOTES:
| Two 2.078 inch diameter housings, each made from either aluminum or plastic, are available for driven gears with 34 or more teeth. One fits gears from 34 - 39 teeth and the second one fits gears from 40 - 45 teeth. |
| The driven gear housings go in the tailhousing assembly on all two-wheel drive applications. |
CHRYSLER SPEEDOMETER GEAR INFORMATION
Torqueflite Speedometer Gears
| Drive Gears | Driven Gears |
| 13 teeth - machined into output shaft | 25 teeth - light green |
| 26 teeth - red | |
| 27 teeth - beige | |
| 28 teeth - light blue | |
| 29 teeth - black | |
| 30 teeth - yellow | |
| 31 teeth - green | |
| 33 teeth - yellow | |
| 34 teeth - green | |
| 35 teeth - orange | |
| 36 teeth - red | |
| 39 teeth - green | |
| 40 teeth - orange | |
| 41 teeth - red | |
| 45 teeth - yellow |
NOTES:
| All Torqueflite transmissions usa a 1.75 inch diameter driven gear housing. |
| The driven gear housings go in the tailhousing assembly on all two-wheel drive applications. |
| The housing must be placed in the correct orientation for the particular driven gear being used. The three positions broken down by tooth count are; 25-31, 32-38, 39-45 |
FORD SPEEDOMETER GEAR INFORMATION
Ford Speedometer Gears
| Drive Gears | Driven Gears |
| 6 teeth - machined into output shaft (C6 only) | 16 teeth - tan |
| 7 teeth - machined into output shaft | 19 teeth - tan |
| 8 teeth - machined into output shaft | 20 teeth - orange |
| 9 teeth - machined into output shaft | 21 teeth - red |
| 23 teeth - white 1 |
| Ford drive gears are machined into the output shaft on C3/C4/C5/C6 & AOD transmissions. You may need to remove your tailhousing to determine how many drive teeth your transmission has. |
| 1. This is a retrofit gear to allow the speedometer to function with 3.73 and 4.10 rear end gears. Since the gear tooth pitch is slightly different than OE, the service life of this gear is limited to less than 25,000 miles. |