counting teeth on speedometer drive gears

[Mark H.]

How do you count the number of teeth on a speedometer drive gear? These pictures were in previous threads I re-read today. For the life of me I can't get to 8 teeth on any of them -- as I understand it, the gears in the first 2 photos should have 8 teeth.

??

[Domenic T.]

Re: counting teeth on speedometer drive gears

Mark,
I hear you, I tried to do the same and found that measuring the width was the way to go.

I think I have the wider one that is for 3:70 and lower and I will measure it against the narrow more comon gear when I get to the shop today.

I will post it.

DOM

[Wayne M.]

Re: counting teeth on speedometer drive gears

How do you count the number of teeth on a speedometer drive gear? These pictures were in previous threads I re-read today. For the life of me I can't get to 8 teeth on any of them -- as I understand it, the gears in the first 2 photos should have 8 teeth.

??

I can't remember which drive gears I used for the first two pics, but the third is definitely a 4.56 driven steel gear and the 6-tooth drive. I've shown in the attached thumbnail how to determine the number of teeth (impossible to count directly across the face of the gear, as only about 3 or 4 are in play at a time).

Count the number of times a tooth merges at the circumference for one complete turn of the gear. I've marked in black ink on this one.

[Domenic T.]

Re: counting teeth on speedometer drive gears

Here you go,
I took pictures of the big & small gear.

The best way to tell is to measure them, as you can see the diameter is larger for the 3:70 to 4:56.

The comon one for the 3:55 to 3:08 is smallest in width and diameter.

The large measures ABOUT 1.883 outside diameter amd .609 width.

The small is 1.755 & .525. That can be done with a measure.

DOM