can't decide if its worth it 2.73 open to 3.42 posi

Discussion in 'Transmission & Driveline Topics' started by 351maverick, Sep 11, 2019.

  1. black_aerocoupe

    black_aerocoupe Veteran Member

    Messages:
    519
    Likes Received:
    19
    Joined:
    Jun 3, 2008
    Location:
    McD's @ the Pavillions, AZ
    That's the textbook ideal rear for your (as-stock) vehicle unless you need to go back and run 0 offset wheels. Or need a strength upgrade.

    An '88 Formula starts life with a choked-head-intake ports engine, or a choked-port-intake-mani that is matched better to 3.42 than it would be to 4.10.

    Drivability around town and country is better with a 3.42. Unless you're putting mega hwy miles on, or otherwise prioritizing mileage and need to keep the 2.73, go for it, absolutely.

    A V8 '98 was an Auburn, with an SLP Torsen option. Ideally, a '99-02 rear has a standard (no frictions) Torsen, unless the car was SLP-"upgraded" to an Auburn those years.

    Your tach, speedo, math or all 3 are off.
     
    dave@ztech likes this.
  2. SRGN

    SRGN Veteran Member

    Messages:
    681
    Likes Received:
    239
    Joined:
    Feb 20, 2009
    Location:
    Central NJ
    Do it. You will notice the difference, and the car will be more fun to drive. I've gone from a 2.73 to a 3.23 and noticed a vast improvement. Plus the 4th gen rear disc brakes are much better.
     
  3. big gear head

    big gear head Veteran Member

    Messages:
    6,239
    Likes Received:
    102
    Joined:
    Jul 30, 2001
    Location:
    Central City, Ky.
    Just a warning, if you have been doing one wheel burnouts and the tread on the right tire is less than the tread on the left tire then you need to replace the tires. If you use a LSD with tires that have uneven tread wear, unequal air pressure or different size tires then you will wear it out quickly and cause the oil to run hot.
     
  4. GoldenOne7710

    GoldenOne7710 Equal Opportunity Offender Lifetime Gold Member

    Messages:
    5,037
    Likes Received:
    567
    Joined:
    Jun 23, 2004
    Location:
    Athens, GA
    I did a 2.56 swap to 3.42 ratio behind a TH350. Made all the difference in the world. Can't go wrong behind a 700R4.
     
    351maverick likes this.
  5. 80sz

    80sz Veteran Member

    Messages:
    3,293
    Likes Received:
    472
    Joined:
    Feb 2, 2014
    Location:
    Buffalo,n.y.
    You done yet ??? What’s takin so long
     
    70-camaro likes this.
  6. Jaxons nasty z

    Jaxons nasty z New Member

    Messages:
    25
    Likes Received:
    6
    Joined:
    Dec 25, 2019
    Location:
    midwest
    3:42 is like the perfect street gear for older cars with 4 and 5 speed tranys . I run 4:11 with super t-10 and the tires size is key . Im running 275/35r20 thats 27” tall and its great . Im in the process of raising and running 28/12-15 28” tall . With your short tires 3:42 is a pretty big jump from 2:73 . Gas mileage will change and no more cruising 70 or 80 unless you go to some new 6,7, or 8 speed tranys . I absolutely love 3:42 for a street machine
     
  7. 1980RS

    1980RS Veteran Member

    Messages:
    3,891
    Likes Received:
    834
    Joined:
    Jun 17, 2006
    Location:
    MN
    I can tell you this, I put 4.10 gears in my 94 Z/28 with a 2.66 low T56 and it was a blast to drive from the 3.42 gears but if I were to have a 700R4 then I would use either a 3.23 or 3.42 and the most I would use with that auto would be a 3.55 gear. 4.10 gear with a 3.06 low gear makes 1st gear absolutely worthless unless you have like 31" tall tire like what we use in drag racing.
     
  8. xten

    xten Veteran Member

    Messages:
    3,349
    Likes Received:
    2,140
    Joined:
    Sep 24, 2014
    Location:
    Pittsburgh, Pa.
    I agree 100%. I had 4.10's with a 700R and 1st was a joke. Distant memory. Went backwards to 3.89's (9") and wish I would have gone more shallow. Kid has an 8 sec. 1st gen turbo street car with 3.55's and he's going to 3.23's. He doesn't know it yet, but I'm going to steal his 3.55 pig.
     
  9. Jaxons nasty z

    Jaxons nasty z New Member

    Messages:
    25
    Likes Received:
    6
    Joined:
    Dec 25, 2019
    Location:
    midwest
    Thats a no brainer . 3:42 with some 255/60 and youll be rockin . My second gen is 4:11 with bw super t 10 . I just put 15” on with 295/50r15 and i havent driven it yet but i know ive been here , its too much . Im going with the 28/12 15 to get the height i need with 4:11 . Your wrong if you think 2:73 -3:42 isnt much . Thats alot really . Do it and if you want to rock run short tires and if your not happy with the gas go with your extra set of taller tires . My opinion 3:42 is the perfect old school gear . Superman had 3:42 and i loved it being automatic
     

    Attached Files:

  10. HOGDADDY

    HOGDADDY Veteran Member

    Messages:
    418
    Likes Received:
    14
    Joined:
    Jun 8, 2005
    Location:
    Birmingham,Alabama
    Personally, I like the 3:73 posi with the 700 R4 in my 86 truck. It has stock 15" wheels.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.