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Hypothetical transmission project

Discussion in 'Civic and del Sol - EG and EK' started by 95BlckDelSol, May 27, 2008.

  1. 95BlckDelSol

    95BlckDelSol New Member

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    Ok n00b here with a hypothetical transmission project.

    Would it be possible to replace the 5 gear in a stock transmission on a 1995 Honda Del Sol Si with one from the S version. All my research say's its possible, and the whole goal of the project is to cut engine RPM's in 5th gear while maintaining the acceleration on gears 1 through 4.
     
  2. frodotoolbox

    frodotoolbox 92 civic si d15b

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    yeah they are both d series so it should work but the s model is a d15 so the rpms will be a little shorter but you will bring it up slower so it would be almost the same.but yes it should be possible i dont see why not.
     
  3. frodotoolbox

    frodotoolbox 92 civic si d15b

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    if your doing it let me know how well it works out and if it pulls any better in fifth.
     
  4. 95BlckDelSol

    95BlckDelSol New Member

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    I thought so but does anyone have any idea by how much the rpm's will be cut. Currently at 75 mph I'm turning 4000 rpms.
     
  5. 95BlckDelSol

    95BlckDelSol New Member

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    This is a future project that I'd like to do if it helps with my gas mileage.
     
  6. frodotoolbox

    frodotoolbox 92 civic si d15b

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    at 75 im only at like 3500 but idk i might want to check that out. d15 redlines at 6800 and the d16 red lines at 7200 so not that much maybe 3-4000
     
  7. BrutalB83

    BrutalB83 Brutal Moderator Moderator VIP

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    That's the idea, he wants to keep RPMs as low as possible in fifth gear so he can get better gas mileage on the freeway.

    It should work since they're both D-series transmissions. People take the fifth gear out of LS transmissions and put them into their B16 and GS-R trannies to create a longer cruising gear. Honestly though, I don't know if it's really worth the time and effort for the minimal gains you'll probably see...
     
  8. 95BlckDelSol

    95BlckDelSol New Member

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    Would I see a larger differance if I switched the final drive and the 5th gear? Like before I don't suppose anyone could ball park the RPM differance from what I currently experiance (4000 @ 75 mph)? I don't suppose anyone knows if there is compatable gear for my transmission that has a lower ratio than 0.750 or even 0.702?
     
    Last edited: May 27, 2008
  9. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    You can swap them. Just make sure to swap the entire gear SET for 5th gear and not just the one cog, otherwise nothing will work right for 5th gear.

    You can swap the final drive too- again, it's a set, not just one- the ring gear and whatever the name of the gear is that meshes with it (can't remember right now).

    If you want to find out your RPM reduction, just find the percentage difference between your current ratio and the new ratio, then take that much off your RPM at your desired speed. If you go from a .770 to a .700 5th gear ratio, you just dropped your 5th gear RPMs by 10%.
     
  10. delsol88

    delsol88 Blinker Fluid Specialist

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    i would guess no more than 300-800 drop in rpm.....maybe close to 2 or 3 mpg. honestly not worth it.
     
  11. delsol88

    delsol88 Blinker Fluid Specialist

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    no calesta that would be 11% lol not to be an ass but that is the answer
     
  12. BrutalB83

    BrutalB83 Brutal Moderator Moderator VIP

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    He was close enough, don't you think?
     
  13. t3t4delsol

    t3t4delsol New Member

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    I came across this site about a year ago and it might really help you out its all about honda trannys and gear ratios

    bensebuilt
     
  14. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Oops, actually 9.09%, not 10% or 11%. I went the wrong way. I'm usually making gear ratios shorter, not longer. ;) .7 to .770 would be a 10% reduction in gear ratio. ;)
     
  15. delsol88

    delsol88 Blinker Fluid Specialist

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    right you are sir, right u are;)
     
  16. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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  17. 95BlckDelSol

    95BlckDelSol New Member

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    Thanks everyone for the information it has been most enlightening.:usa:
     
  18. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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  19. philyphreak2127

    philyphreak2127 Back in the Game

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    how much would changing out the 5th gear cost if the labor was done by him? Just wondering...
     
  20. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    Just parts? Less than $200 if you buy the parts new. I'd just find a used transmission with a broken differential or something and gut it.
     
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