Aussie 4 speed m21 speedo gear selection

[Andrew Ivanic]

Hi Guys,

Can anyone please assist me on a speedo gear tooth numbers I require for my car.

It's a 1984 vk commodore 5l with a Aussie m21 4 speed gear box. My tyre size is 205/65/15. My diff ratio is 3.08.
I have a 22 tooth speedo gear and when my speedo says I'm doing 80klm/h I'm actually doing around 105klm/h so it's off by 25km/h.
Do I need a speed hear with more or less teeth ?
There's a formula on holdenpedia but i can't work it out. Thanks

 

[Vin999]

You need the 19 tooth Pink driven gear will read 102km at 100 road speed. Try the website yourself.

http://www.centauriaudio.com.au/tchc4878/speedocalc.html

 

[Andrew Ivanic]

Legend thank you

 

[rambunctious]

I probably have one.
Going to Bris today so must remember to bring them back with me.


edit
Yep back from Bris and I have a pink 19 tooth.
Got some toilet paper while I was down there.
PM me if you want the drive not the toilet paper, already gave the toilet paper to local family cause I knew they had none.