Reference Manual
Chapter 2: Transmissions: Speedometer Gears
The speedometer cable in a G body is driven by a set of gears
in the transmission. A drive gear is connected to the transmission output shaft
and turns at the same speed as the driveshaft. A driven gear is installed on the
transmission end of the cable and meshes with the drive gear. The gears are
choosen to provide a ratio that will rotate the speedometer cable 1000 times per
mile. Additionally, a ratio adaptor may be used if a close match can not be made
with available gear combinations.
THM200-4R Gears
| Drive |
Color |
p/n |
Driven |
Color |
p/n |
|
|
| 10 teeth |
Green |
8639906 |
26 teeth |
Brown |
25502669 |
| 11 teeth |
Orange |
8634965 |
27 teeth |
Black |
25524923 |
| 12 teeth |
Red |
8634935 |
28 teeth |
Yellow |
25524921 |
| 13 teeth |
White |
8634934 |
29 teeth |
Green |
25524924 |
|
|
|
30 teeth |
Blue |
25524925 |
|
|
|
31 teeth |
White |
403417 |
THM200C, THM250(C), THM350(C) and THM375B Gears
| Drive |
Color |
p/n |
Driven |
Color |
p/n |
|
|
| 7 teeth |
Pink |
|
18 teeth |
Brown |
3987918 |
| 8 teeth |
Orange |
6261783 |
19 teeth |
Natural |
3987919 |
| 9 teeth |
Green |
6261782 |
20 teeth |
Blue |
3987920 |
| 10 teeth |
Red or Purple |
8261785 |
21 teeth |
Red |
3987921 |
| 17 teeth |
Red |
8628793 |
22 teeth |
Gray |
3987922 |
| 18 teeth |
Blue |
|
34 teeth |
Light Green |
9774413 |
| 19 teeth |
Yellow |
8628891 |
35 teeth |
Orange/Pink |
9780387 |
| 20 teeth |
Brown |
|
36 teeth |
White |
1359270 |
|
|
|
37 teeth |
Red |
135971 |
|
|
|
38 teeth |
Blue |
1359272 |
|
|
|
39 teeth |
Brown |
1359273 |
|
|
|
40 teeth |
Black |
1362048 |
|
|
|
41 teeth |
Yellow |
1362195 |
|
|
|
42 teeth |
Green |
1362049 |
|
|
|
43 teeth |
Purple |
1362196 |
|
|
|
44 teeth |
Dark Gray |
9780470 |
|
|
|
45 teeth |
Light Blue |
9775187 |
THM375, THM400, THM700R4 and THM4L60 Gears
| Drive Gear |
Color |
p/n |
Driven |
Color |
p/n |
|
|
| 7 teeth |
Red |
|
16 teeth |
|
(truck) |
| 8 teeth |
Black |
6261783 |
17 teeth |
|
(truck) |
| 15 teeth |
Brown or Gray |
8642620 |
18 teeth |
Brown |
(truck) H |
| 16 teeth |
Orange |
|
19 Teeth |
Dark Aqua |
(truck) J |
| 17 teeth |
Red |
8640517 |
20 teeth |
Silver |
(truck) K |
| 18 teeth |
Yellow or Blue |
8640518 |
21 teeth |
Red |
(truck) L |
| 19 teeth |
Yellow or White |
|
22 teeth |
Gold |
(truck) M |
| 20 teeth |
Green |
|
23 teeth |
Maroon |
(truck) |
| 21 teeth |
Black |
|
24 teeth |
Dark Blue |
(truck) |
|
|
|
34 teeth1 |
Light Green |
9774413 |
|
|
|
35 teeth1 |
Orange/Pink |
9780387 |
|
|
|
36 teeth1 |
White |
1359270 |
|
|
|
37 teeth1 |
Red |
135971 |
|
|
|
38 teeth1 |
Blue |
1359272 |
|
|
|
39 teeth1 |
Brown |
1359273 |
|
|
|
40 teeth2 |
Black |
1362048 |
|
|
|
41 teeth2 |
Yellow |
1362195 |
|
|
|
42 teeth2 |
Green |
1362049 |
|
|
|
43 teeth2 |
Purple |
1362196 |
|
|
|
44 teeth2 |
Dark Gray |
9780470 |
|
|
|
45 teeth2 |
Light Blue |
9775187 |
|
|
1THM700R4, THM4L60: Use sleeve 25512340 |
|
2THM700R4, THM4L60: Use sleeve 25512339 |
Ratio Adaptors
| Marking |
p/n |
Ratio |
|
|
| A |
3932220 |
0.7333 |
| C |
3950352 |
0.8241 |
| D |
326569 |
0.9744 |
| H |
332537 |
0.8241 |
| J |
3950350 |
1.3000 |
| K |
330192 |
0.7333 |
| V |
3925673 |
1.1111 |
| W |
3925669 |
0.9444 |
| X |
3950348 |
1.2020 |
| BD |
368022 |
0.9444 |
| BG |
368025 |
1.2020 |
| BH |
368026 |
1.3000 |
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