3.73 to 3.23

Discussion in 'Transmission & Driveline Topics' started by slamdik, Dec 9, 2011.

  1. slamdik

    slamdik Member

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    How much would my et,s change if I change my 373s to 323s.
    Let's say the 373s are ideal for 1/4 mile for my set up.How much slower would it be?
     
  2. ProStreet78z28

    ProStreet78z28 Banned

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    IMHO....No change in ET, but you also have to consider your combo and powerband.
     
  3. slamdik

    slamdik Member

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    That is what I want to hear.If someone has done a similar change(less gear only) I'd like to see what effect it had at the track.
     
  4. mildthing

    mildthing Veteran Member

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    Why, are the 3.73s whining? Or is it the high RPM at cruise getting annoying?
    Twice I've gone the wring way in gearing, as you're proposing. But neither time did I take it to the dragstrip.
    In my '88 IROC-Z, when I sold it, I pulled my 3.73:1 with Miller locker, due to worries about liability. I installed a 3.42:1 with open diff, then went for a test drive. It kept dropping out of overdrive. Annoying. Had to change the cam.
    My baby blue '78, I tried a 3.42:1 gear in that, but then I had to move to another city because of my job. So in went the original 2.41:1 again, which later got replaced with a 3.08:1.
    As it is, assuming a TH350 or M20, you have about a 9.4:1 combined ratio in first. If you swap, you'll drop to a lame 8.1:1, and it will feel miserable. You'll start thinking about a better first gear.
    As for dragstrip times, going up numerically in gear ratio tends to help times unless you're turbocharged, so this swap should add a few tenths.
     
  5. slamdik

    slamdik Member

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    I said eff it and bought the 323 rear.I got it for $200.

    I'll let you guys know if it was a $200 mistake after I install it.
     
  6. Todd80Z28

    Todd80Z28 Moderator Staff Member Lifetime Gold Member

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    It can always be sold if it is. You don't have much to lose, beyond your install time, to try it out.
     
  7. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    what rpm are you crossing the stripe at now and what is your rear tire dia and converter specs !!


    i've got a friend running a 70 camaro with a 750-800hp 548BBC ,T400 , 3.42 gears and 28" tall drag radials and running low 10 second 125-128mph passes foot braking and has never tried using the trans brake yet
     
    Last edited: Dec 18, 2011
  8. TEAMMUNCIE

    TEAMMUNCIE New Member

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    My guess is you will lose about 0.3 to 0.5 seconds thru the quarter. Search rpm calculator and run the numbers. Remember your final drive ratio is a multiplication of the gear your in x the rear gear. I believe the 350 has a 2.52 low gear or close to that. Using that 2.52 x 3.73 = 9.40. 2.52 x 3.23= 8.14. That will make a big difference on how the car launches!!
    .
     

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