3.55 or 3.73?

Discussion in 'Transmission & Driveline Topics' started by 72 pile, Jun 19, 2011.

  1. 72 pile

    72 pile Veteran Member

    Messages:
    101
    Likes Received:
    0
    Joined:
    Sep 16, 2003
    Location:
    Woodland, Ca
    running 3.23's with a 295x50x15 tire and a tremec tko600 ( 5 speed) w/ .82 OD. Took the car to the track last week for the first time and was not happy with the 3.23's at all. suggestions on gear choices with the tremec?
     
  2. Aceshigh

    Aceshigh Veteran Member Lifetime Gold Member

    Messages:
    26,757
    Likes Received:
    6
    Joined:
    Apr 9, 2001
    Location:
    Boondocks
    "Not happy" doesn't tell anyone enough.....

    What are you shooting for ??
    If it's strictly faster E.T.'s get the biggest gear that's reasonable.
     
  3. K5JMP

    K5JMP Veteran Member Lifetime Gold Member

    Messages:
    10,216
    Likes Received:
    9
    Joined:
    Oct 19, 2006
    Location:
    MORTUORUM VENATOR - Z.R.T.
    3.73's if that the only 2 choices...
    Tommy was running 4.11's and I beleive he went to 3.73's.
    I have 3.90's in mine and no OD.. pulls like snot when it hooks, but not so good on the hiway:crazy:
     
  4. 72 pile

    72 pile Veteran Member

    Messages:
    101
    Likes Received:
    0
    Joined:
    Sep 16, 2003
    Location:
    Woodland, Ca
    acceleration was slow once the tires quit spinning. going with stickier tires and different gears. with the 3.73 gears and my OD, 70 mph would be about 2700rpm. Should be good considering my cam doesnt wake up until 3000rpm.
     
  5. 1980RS

    1980RS Veteran Member

    Messages:
    3,254
    Likes Received:
    545
    Joined:
    Jun 17, 2006
    Location:
    MN
    It all depends on the first gear in the TKO, If you have a 3.27 low gear 3.23 rears should be fine. If you have like a 2.66 low gear in the trans then you would need like a 4.10 rear gear to make it come out of the hole good. Now this all depends on how much tq. you're engine makes.

    I used to run the 3.11 first gear vega tranny with 4.10 rear gear, Car came out of the hole real hard, but those trannys were just junk and I did not get more than 90 days out of most of them. But it was fun.
     
  6. ProStreet78z28

    ProStreet78z28 Banned

    Messages:
    784
    Likes Received:
    1
    Joined:
    Feb 19, 2011
    Location:
    In Transit to California
    Go with the 3.73s with the TKO 600
     
  7. DesmoEd

    DesmoEd Veteran Member

    Messages:
    1,138
    Likes Received:
    7
    Joined:
    Sep 9, 2009
    Location:
    Frisco, TX


    Thats the key - matching the cam to cruise rpm.

    I have the 3;73/.82 combo in my 69 vette and it works great w/27in tire. The TKO600 comes 2.87 1st regardless of .64/.82 OD. Its the 500 that has steeper 3.xx 1st gear

    The .82 600RR is really a close ratio 5 speed instead of a 4 speed w/OD. Coupled to a powerplant that likes some rpm and you get :D

    Its superb in my '69. The car is light and the engine is happy in cruise at 2800-3000rpm:cool:
     
  8. 79powershifter

    79powershifter Veteran Member

    Messages:
    266
    Likes Received:
    0
    Joined:
    Apr 22, 2009
    Location:
    Southgate Mi
    I don't think 3.55 are available any more. You can get 3.42 or 3.73.
     
  9. NYH1

    NYH1 Veteran Member

    Messages:
    1,594
    Likes Received:
    12
    Joined:
    Feb 27, 2010
    Location:
    Central New Yorkistan
    What's the power range of your engine? 3.90's or 4.10's might work.
     
  10. 72 pile

    72 pile Veteran Member

    Messages:
    101
    Likes Received:
    0
    Joined:
    Sep 16, 2003
    Location:
    Woodland, Ca
    engine is a 355 with 10.5:1 compression, world heads, full roller rockers (1.5), 305H cam, team-g intake, msd 6a box, msd pro billet dist., dynatech 1 7/8 headers, holley avenger EFI....
    Makes good power from 3000-6500rpm.
     

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.