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 Tree14Likes
  • 1 Post By 34_40
  • 4 Post By rspears
  • 2 Post By Indy
  • 2 Post By 36 sedan
  • 1 Post By Indy
  • 2 Post By 36 sedan
  • 2 Post By rsinor

Thread: geering for ford 9 inch rear
          
   
   

Reply To Thread
Results 1 to 14 of 14
  1. #1
    tyler1967ss is offline CHR Junior sMember Visit my Photo Gallery
    Join Date
    Apr 2020
    Location
    andover
    Posts
    2

    geering for ford 9 inch rear

     



    hi, new guy tyler here,recently purchased at auction 1967 chevelle with ford 9 inch rear super low geering, original 4 speed standard trans, 396 bb, rear tires are 255/60r15. can someone please tell me what to get for daily driver,ocational hiway gears? i like to order from summit racing, if you could recommend gears and part number that would be so great.thank you.tyler

  2. #2
    34_40's Avatar
    34_40 is offline CHR Member Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    New Bedford
    Car Year, Make, Model: 34 Ford 3W Coupe Replica
    Posts
    14,605

    A simple SWAG on my part. 3.25 or 3.50 or 3.73 / but there are many variables - even things like tire O.D. make a difference.
    36 sedan likes this.

  3. #3
    rspears's Avatar
    rspears is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Sep 2007
    Location
    Gardner, KS
    Car Year, Make, Model: '33 HiBoy Coupe, '32 HiBoy Roadster
    Posts
    10,979

    Those rear tires have an OD of just 27" and the stock 4 speed is a 1.0 final drive ratio. If you run 3.25 gears you'll be turning 2831rpm at 70mph. If you jump up to a 30" rear OD tire the cruise revs drops to only 2548rpm. If you drop down to 3.00 gears those numbers drop to 2613 (27's) and 2352 (30's) at 70 down the road. You've got to balance what you want for driveability, economy and performance.
    Mike P, ted dehaan, NTFDAY and 1 others like this.
    Roger
    Enjoy the little things in life, and you may look back one day and realize that they were really the BIG things.

  4. #4
    tyler1967ss is offline CHR Junior sMember Visit my Photo Gallery
    Join Date
    Apr 2020
    Location
    andover
    Posts
    2

    thanks, if i want to keep tire size, what should i get for gears to run about 2300 rpm at 70 mpr?

  5. #5
    Indy's Avatar
    Indy is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2020
    Location
    Yukon
    Car Year, Make, Model: 1920 TBucket , 2008 Navigator
    Posts
    17

    Since this thread is not terribly old, just a few months then I thought I would add to it for
    others that read it later.


    A rear gear ratio of 2.7, trans final ratio of 1:1 and tires diameter of 27 inches would yield

    a 2352 rpm at 70 mph.


    If you have an OD trans with a final ratio of 0.7, then you could use a rear ratio of 3.9

    and the engine would turn 2378 rpm.



    TireSize_RPM-Calcs01-1.jpg


    TireSize_RPM-Calcs01-2.jpg
    Last edited by Indy; 08-03-2020 at 04:00 PM.
    glennsexton and 36 sedan like this.
    Happiness is G-Force !

  6. #6
    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
    Posts
    9,476

    What I do when I want low gears I put in the low pig I have a separate pig for hi way. Its is easier to pop the pig out than change gears
    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

  7. #7
    shine's Avatar
    shine is offline CHR Member Visit my Photo Gallery
    Join Date
    Nov 2003
    Location
    bluff dale texas
    Car Year, Make, Model: 47 inderweed
    Posts
    2,108

    need to keep in mind low gears at high speed create a lot of heat. overdrive/short tires/low gears can lead to a burnt up rear end.

  8. #8
    Indy's Avatar
    Indy is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2020
    Location
    Yukon
    Car Year, Make, Model: 1920 TBucket , 2008 Navigator
    Posts
    17

    Quote Originally Posted by cffisher View Post
    What I do when I want low gears I put in the low pig I have a separate pig for hi way. Its is easier to pop the pig out than change gears
    OK, I will bite ...... what is a PIG ???
    .
    Last edited by Indy; 08-03-2020 at 04:06 PM.
    Happiness is G-Force !

  9. #9
    Indy's Avatar
    Indy is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2020
    Location
    Yukon
    Car Year, Make, Model: 1920 TBucket , 2008 Navigator
    Posts
    17

    Quote Originally Posted by shine View Post
    need to keep in mind low gears at high speed create a lot of heat. overdrive/short tires/low gears can lead to a burnt up rear end.
    Good point, just because the engine is loafing along does NOT mean the rear gears are doing the same.
    .
    Happiness is G-Force !

  10. #10
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,899

    Quote Originally Posted by Indy View Post
    OK, I will bite ...... what is a PIG ???
    .
    rear gear case with gears intact, aka pumpkin, third member.
    cffisher and rspears like this.

  11. #11
    Dave Severson is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Jul 2003
    Location
    Madison
    Car Year, Make, Model: '67 Ranchero, '57 Chevy, '82 Camaro,
    Posts
    21,160

    I have a friend who still tells horror stories about when he got out of the Navy in '72 and drove back to S. Dakota from San Diego in July in a big block Chevelle with 4.11:1 gears, no air conditioning, a pregnant wife, and 2 dogs!!!! The right gearing is very important! PS, they're still married!
    Yesterday is history, tomorrow is a mystery, Live for Today!
    Carroll Shelby

    Learning must be difficult for those who already know it all!!!!

  12. #12
    Indy's Avatar
    Indy is offline CHR Member Visit my Photo Gallery
    Join Date
    Aug 2020
    Location
    Yukon
    Car Year, Make, Model: 1920 TBucket , 2008 Navigator
    Posts
    17

    rear gear case with gears intact, aka pumpkin, third member.
    Guess I should have figured that one out !
    .
    34_40 likes this.
    Happiness is G-Force !

  13. #13
    36 sedan's Avatar
    36 sedan is offline CHR Member Visit my Photo Gallery
    Join Date
    Apr 2012
    Location
    american canyon
    Car Year, Make, Model: 36 Ford Sedan, 23 T Bucket
    Posts
    1,899

    Quote Originally Posted by Indy View Post
    Guess I should have figured that one out !
    .
    Don’t beat yourself up, it’s slang terms. Now you know and can stump someone else.
    Dave Severson and Indy like this.

  14. #14
    rsinor's Avatar
    rsinor is offline CHR Member Visit my Photo Gallery
    Join Date
    Jul 2020
    Location
    Tulsa
    Car Year, Make, Model: 32 Ford Vicky & 40 Ford dlx coupe
    Posts
    12

    Quote Originally Posted by Dave Severson View Post
    I have a friend who still tells horror stories about when he got out of the Navy in '72 and drove back to S. Dakota from San Diego in July in a big block Chevelle with 4.11:1 gears, no air conditioning, a pregnant wife, and 2 dogs!!!! The right gearing is very important! PS, they're still married!
    I'm sure he realizes now, but if she survived that she's a keeper.
    Dave Severson and 36 sedan like this.
    Roy
    ENJOY LIFE NOW........IT DOES HAVE AN EXPIRATION DATE, SO......
    LIVE WELL, LOVE MUCH, LAUGH OFTEN

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