Thread: Speedo drive gears

Many thanks Brian. Exactly what I needed to know.
I've got a 10T fitted, so using a 9T calculates out to be get my speedo back to nearly correct, and since the diamater of the worm is the same I'll just try it with the 20T driven gear that I'm currently running (rather than buying the new blue gear straight up).

Out of interest, are you certain that 12T worm is RR (and not Stage1). Both my Stage1 boxes definitely had the 12T, and the NOS RR one I currently have fitted is 10T.

Steve

Can't be certain Steve, as it's from a box I bought supposedly from a RR. But who knows where it originally came from. I have a few more here still intact so when I get a chance (maybe tomorrow), I will pull one apart and check it. I have 1 that I know for certain came from an early RR as I pulled it out myself. Check this space tomorrow night

Originally Posted by steveG

Thanks. Cool here too - about 8 deg and dropping rapidly.
If you happen to find a spare set that you want to get rid of let me know.
Online pricing for that worm is over $100, and 50GBP from UK, so I'll be chasing a used one

Steve

I have a couple of County LT230's here, I will check what speedo gears are in them - might be able to find a set for you.

Originally Posted by Bearman

I have a couple of County LT230's here, I will check what speedo gears are in them - might be able to find a set for you.

Now THAT would be awesome

Steve

Where would i get a list of all the gear drives and ratio's? Want to see if something can be matched for a 1.003 and 35's

Speedo Drive Worm Gears

On the output shaft itself there are 3 gears that I'm aware of. 12, 10, and 9 teeth. AFAIK all LT230's have the 9T one.

Steve

Thanks Steve, so do i have to count now. Anyone know what gears suit what ratio's?

Originally Posted by Vern

Thanks Steve, so do i have to count now. Anyone know what gears suit what ratio's?

No chart that I know of, but since its on the output shaft you don't need to worry about gear ratios etc in the box/transfer - just diffs and tyres.

I'm running 255/85's (so 33.1"), the 9T shaft gear and a 20T driven gear. Speedo reads about 5% over (105 @ 100km/h true)
So assuming you've got the same (standard) diffs, 35/33.1*20T*1.05 = 22.2.

If I haven't cocked that up you need a 22T driven gear and the same 9T shaft gear that should already be in it.

Steve