Jump to content

Recommended Posts

Yes most likely, here is formula that will get you close. Drive gear teeth X axle ratio X tire revolution per mile divide by 1001 = driven gear. An example most trans drive teeth are 6,7,8.

Here is my 73 

7x3.70= 25.9

25.9 x721.9=18697

18697 divided by 1001=18.69 round it up and your at 19 tooth driven gear.

Use this site to help determine revolution per mile depending on your tire size. https://tiresize.com/calculator/

Hopefully somebody has a shorter way of doing this and will share it here, its just what i use.

Link to post
Share on other sites

Simple method *if* your speedo was accurate prior to the swap. 

Divide 3.50 by 3.00 = 1.166

Multiply 1.166 times the number of teeth on your current driven gear - you need *more* teeth on the driven gear to slow the speedometer. 



Link to post
Share on other sites

Here's some more information about Ford speedometer gears and a calculator.





“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...