[rohrt]

I found this on a chevelle site. So I would guess I'm running the 17 tooth Red?

THM400 Speedometer Drive Gears
Part
Number Teeth Color Clip Price
8629547 15 Brown/Gray None $ 3.61
8623311 16 Orange None $14.34
8629548 17 Red None ***
8629549 18 Blue None ***
8629550 19 White/Yellow None ***
8629551 20 Green/Brown None ***
8623316 21 Black None ***

[HWYSTR455]

The drive gear goes on the output shaft of the trans, the driven gear goes in the bullet and attached to the cable. Not sure if I have that reversed, but believe that's correct.

Drive gears are marked with a stripe, you can look through the bullet hole with a flash light and should be able to see the stripe. Sometimes the whole face of the drive gear is painted.

So a red driven gear is 37 teeth, according to the chart on TCI.

You can use a sharpie, mark one tooth, then go around and count.

I only use programmable speedos now, so it's been a while since I've dealt with this.

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[HWYSTR455]

Low number of teeth usually points to a drive gear, driven gears have more teeth.

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[HWYSTR455]

I believe each tooth on a driven gear equates to @ 2.5 mph change.

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