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Speedometer
Information
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. Click here for
applications & part numbers.
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) |
Try this handy custom calculator. It will do
all the work for you. If you don't know your tire diameter, calculate it below
using the P-metric sidewall designation.
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 |
| Click here for
part numbers. |
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. |
|
* - 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 - orange |
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 |
| Click here for
part numbers. |
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 |
| Click here for part numbers. |
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. |
|
* - 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 |
| Click here for part numbers. |
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 |
* - This gear is shipped in all TCI Street
Fighter 700-R4 transmissions.
Notes:
|
Two 2.078" 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 |
| Click here for part numbers. |
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 use a
1.75" 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 |
| Click here for part numbers. |
|
| |
|
Notes:
|
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. |
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