Welcome to Club Hot Rod!  The premier site for everything to do with Hot Rod, Customs, Low Riders, Rat Rods, and more. 

  •  » Members from all over the US and the world!
  •  » Help from all over the world for your questions
  •  » Build logs for you and all members
  •  » Blogs
  •  » Image Gallery
  •  » Many thousands of members and hundreds of thousands of posts! 

YES! I want to register an account for free right now!  p.s.: For registered members this ad will NOT show

 
Like Tree3Likes
  • 1 Post By DennyW
  • 2 Post By cffisher

Thread: Ford speedo gears
          
   
   

Reply To Thread
Results 1 to 14 of 14
  1. #1
    junkyardjeff's Avatar
    junkyardjeff is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2003
    Location
    Dayton
    Car Year, Make, Model: 37 chevy p/u 55 ford convertable
    Posts
    614

    Ford speedo gears

     



    I need a gear with one more tooth and it should be right on,I have a 21 tooth gear and would like to find a 22 and anyone have any parts manuals. The parts guy at the dealer I was at the other day did not have a way to look up old part numbers,

  2. #2
    Driver50x's Avatar
    Driver50x is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2016
    Location
    Saint Petersburg, Florida
    Posts
    254

    Did you try looking on EBay? A lot of sellers there list the gears according to tooth count.
    Steve

  3. #3
    Driver50x's Avatar
    Driver50x is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2016
    Location
    Saint Petersburg, Florida
    Posts
    254

    Also, it’s easy to mathematicaly calculate a gear change, so you don’t have to guess which gear to buy.

    How far is your speedo off, and what speed did you check it at?

    Adding one tooth to a 21 tooth gear, (1 divided by 21) will slow down the speedometer by 4.7%

    60 MPH minus 4.7% equals 57 MPH. (0.047x60 equals 2.82 MPH change)
    Steve

  4. #4
    junkyardjeff's Avatar
    junkyardjeff is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2003
    Location
    Dayton
    Car Year, Make, Model: 37 chevy p/u 55 ford convertable
    Posts
    614

    Its about 2 too fast and can not remember the speed it was checked.

  5. #5
    Mike P's Avatar
    Mike P is online now CHR Member Visit my Photo Gallery
    Join Date
    Mar 2003
    Location
    SW Arizona
    Car Year, Make, Model: 57 Plymouth, 37 Dodge PU, 83 El Camino
    Posts
    3,307

    A local transmission shop is often another good source for gears.

    .
    I've NEVER seen a car come from the factory that couldn't be improved.....

  6. #6
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    outahere
    Posts
    1,050

    Most states allow 5 mph over the speed limit.
    Driver50x likes this.

  7. #7
    junkyardjeff's Avatar
    junkyardjeff is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2003
    Location
    Dayton
    Car Year, Make, Model: 37 chevy p/u 55 ford convertable
    Posts
    614

    Found none on ebay,plenty of 21 and 23 tooth gears but no 22 so I am going to leave it alone. I want to get it as close as I can to check gas mileage.

  8. #8
    mrmustang's Avatar
    mrmustang is offline Global Moderator Lifetime Contributor Visit my Photo Gallery
    Join Date
    Apr 2001
    Location
    Greenville
    Car Year, Make, Model: 1969 GT500 Fastback
    Posts
    1,345

    Quote Originally Posted by junkyardjeff View Post
    Found none on ebay,plenty of 21 and 23 tooth gears but no 22 so I am going to leave it alone. I want to get it as close as I can to check gas mileage.
    Assuming you are using a stock 55 Ford transmission CLICK HERE


    Suggested speed to clock your speedometer would be 60mph. Believe it or not, the local police will help you do so if you ask.
    Last edited by mrmustang; 10-27-2018 at 01:20 PM.

  9. #9
    junkyardjeff's Avatar
    junkyardjeff is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2003
    Location
    Dayton
    Car Year, Make, Model: 37 chevy p/u 55 ford convertable
    Posts
    614

    Late 70s C-4

  10. #10
    mrmustang's Avatar
    mrmustang is offline Global Moderator Lifetime Contributor Visit my Photo Gallery
    Join Date
    Apr 2001
    Location
    Greenville
    Car Year, Make, Model: 1969 GT500 Fastback
    Posts
    1,345

    Quote Originally Posted by junkyardjeff View Post
    Late 70s C-4
    In that case, Ford, and the aftermarket do not offer a 23 tooth speedometer gear

    These are your options for the C4 automatic transmission.
    19 tooth-tan
    20 tooth-orange
    21 tooth-red
    23 tooth-white

    At this point, you are going to have to deal with tire size changes (small, simple, yet can be costly).

    Another option is to find a measured mile (a real one, not what you see marked on the side of a typical road), take measurements, then send the speedometer itself out for re-calibration to match what you need it to be.

    Looking back, you did not make mention of whether you are using an original or aftermarket speedometer. Which are you using, be as detailed as you can be, include tire sizes (rear only), rear gear ratio, type of rear end, speedometer head, any adapters, etc.

  11. #11
    junkyardjeff's Avatar
    junkyardjeff is offline CHR Member Visit my Photo Gallery
    Join Date
    Jun 2003
    Location
    Dayton
    Car Year, Make, Model: 37 chevy p/u 55 ford convertable
    Posts
    614

    Its almost a tenth of a mile too fast according to the mile markers.

  12. #12
    DennyW is offline CHR Member Visit my Photo Gallery
    Join Date
    Oct 2004
    Location
    outahere
    Posts
    1,050

    Here is a little info. Don't forget to read the notes. And, what Bill said.

    Attachment 70670

  13. #13
    cffisher's Avatar
    cffisher is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2006
    Location
    Constantine
    Car Year, Make, Model: 57 chevy 2 dr wagon /73 Nova hatchback
    Posts
    9,258

    Get a GPS and it will tell you your MPH then look at your speedometer
    johnboy and Driver50x like this.
    Charlie
    Lovin' what I do and doing what I love
    Some guys can fix broken NO ONE can fix STUPID
    W8AMR
    http://fishertrains94.webs.com/
    Christian in training

  14. #14
    Driver50x's Avatar
    Driver50x is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2016
    Location
    Saint Petersburg, Florida
    Posts
    254

Reply To Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink