Gear Ratio Calculator

# of Drive Teeth: Axle Ratio: Tire Diameter:

# of Driven Teeth:

Drive gears

All GM

# of teeth	Gear color	GM part #	Shaft size	Clip size
8	Black	6261783	1.19"	5/16
10	Purple	6261785	1.19"	5/16
18	Green	6260037	1.19"	7/16
19	Natural	8640188	1.19"	7/16
15	Grey	8642620	1.19"	5/16
17	Red	8640517	1.19"	5/16

Small driven gears

Power glide, 200 Metric, TH250, TH350 and TH400

# of teeth	Gear color	GM part #
18	Brown	3987918
19	Natural	3987919
20	Blue	3987920
21	Red	3987921
22	Grey	3987922
23	Black	3980346

Small driven gears

200R-4 and 125 Metric

# of teeth	Gear color	GM part #
26	Brown	25502669
27	Black	410731
28	Yellow	416765
29	Green	403999
30	Blue	561035
31	White	403417

Large driven gears

200 Metric, TH250, TH350, TH400 and 700R-4

# of teeth	Gear color	GM part #
34	Green	9774413
35	Orange	9780387
36	Natural	1359270
37	Red	1359271
38	Blue	1359272
39	Brown	1359273
40	Black	1362048 25513047
41	Yellow	1362195
42	Green	1362049 25513049
43	Purple	1362196 25513050
44	Grey	9780470
45	Lt. Blue	9775187

Speedo gear chart for the 700R/4L60/4L60E

15-Tooth Drive Gear

Gear Ratio	Tire Size	Driven Gear
4.56	33	42
4.56	35	39
4.10	26	45
4.10	27	45
4.10	28	44
4.10	29	43
4.10	30	41
4.10	31	40
4.10	33	38
4.10	35	35
3.73	26	43
3.73	27	42
3.73	27 1/2	41
3.73	28	40
3.73	29	39
3.73	30	38
3.73	31	36

17-Tooth Drive Gear

Gear Ratio	Tire Size	Driven Gear
3.73	28	45
3.73	29	44
3.42	26	45
3.42	26 1/2	44
3.42	27	43
3.42	28	42

18-Tooth Drive Gear

Gear Ratio	Tire Size	Driven Gear
3.23	26	45
3.23	26 1/2	44
3.23	27	43
3.23	28	42