Speedo Gear - for 1963

[Joel T.]

I'm working on my '63 Coupe.. The speedometer reads low compared to actual road speed. I pulled the gear yesterday and it appears to have 20 teeth (yellow?). The rear end is a "CC" which is a 3.55 (Posi)which I have also verified by counting the driveshaft turns. The question is, which is the correct speedo gear (teeth and/or color) for the 3.55. I can't find the answer in any book I currently have....

Much thanks!!

Joel

[Gordon Peterson #4961]

Re: Speedo Gear - for 1963

Hi Joel -

My old parts book says you need p/n 3987921, 21 tooth, red

Pete

[Wayne M.]

Re: Speedo Gear - for 1963

Gordon is correct, but My REALLY old parts book says the red 21-tooth plastic gear used to be originally known by the number 3860344.

You're probably adding a tooth on your count, for the "natural"-colored plastic gear has 19 teeth, and it can appear pale yellow or dirty cream"ish" when saturated with trans oil (also, the blue gear has 20 teeth, usually for 3.36 C2 ratios and tires).

But if you are reading lower than actual, going to 21 teeth will make it WORSE. You need one with FEWER teeth, to spin the sender gear faster for the same rev's of the driving gear on your trans output shaft. There's an 18-tooth brown gear 3860341.

Sounds like your speedo needs re-calibration (does the odometer read correctly ?).

[Joel T.]

Re: Speedo Gear - for 1963

You are right about the teeth and the color... It appears to be yellow but "cream-ish" is also an accurate description of the color!

To answer your other question, the odometer (main and trip) do not work at all. (as do most of the other gauges). I just assumed that the odometer not working would not be directly related to the accuracy of the speedo.

The entire gauge cluster needs to be looked at as nothing (save the ammeter) works! That may well be the best course of action...