I am asking on this board cause they are a bit snippy on the "R" forums, my speedo is 5mph slow, I havent played with them in a while, say the gear is 10 teeth, would I add more teeth or get one with less teeth to speed up the speedometer? I know there is a formula but the tag rusted off and I know not the gear ratio.

 

Your speedometer is 5 MPH slow at what speed?

There are two gears involved with your speedometer. I believe they are called the driven & drive gears. One is inside the transfer case or transmission, the other meshes with that gear and controls the speedometer.

If you want the speedometer to read faster, you could either increase the teeth on the inner gear, or decrease the teeth on the outer gear. By "outer gear" I mean the one that drives the speedometer. If it has fewer teeth, it will make more revolutions for each revolution of the inner gear.

I have been told it is sometimes necessary to replace both gears to fine tune the speedo. This is because in your hypothetical situation, where the gear only has 10 teeth, changing it by even 1 tooth would make a drastic difference.

 

You have to change both gears to make the speedometer read differently. You can't just change one.

 

^ that makes sense.

 

Because if you change the amount of teeth on one, it doesn't mesh with the teeth on the other gear anymore.

 

It reads 5mph slow all speeds. Thanks 89. But, if the gears are about 1 or 2 teeth off, they will mesh, I used to do it on my old trucks and my mustang all the time, I actually have some gears left over somewhere. I will find what gear it has and go down a tooth, if I dont have one I see them on ebay for about $5.00.

 

I've done it too, and ate up the gears in the process.

 

I know one tooth did not matter, but that was on a c6 w\machined teeth.

 

If your speedometer is off by 5 MPH at all speeds, you can only get it correct at one speed with gears. If possible, you need to open up the gauge cluster, pull off the needle, and rotate it by 5 MPH. Or you could just re-mark the gauge.

 

Thats an idea 89, but for now I will live with it. I am the only one who knows how to drive a stick anyway.