Rear gearing

Discussion in 'Drag Racing Forum' started by Boss2083, Apr 15, 2018.

  1. Boss2083

    Boss2083 TMO Intermediate

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    Has anyone went with lower gearing in there Boss. Thinking of putting 4:10s in mine. I put 4:10s in my 99 Cobra and they really made a big difference.
     
  2. stuntman

    stuntman TMO Advanced

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    Depends .What's the top speed of your fastest track?
     
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  3. Swine

    Swine TMO Intermediate

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    Opposite, im considering going to a 3.55 instead of the 3.73 since im running a lower gearing tire of 285/35/18. Id like to go through the traps not on the limiter if i can help it.
     
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  4. ls110

    ls110 John

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    Agreed. I ran the 3.55 and am now running the 3.31 and very happy. I have plenty of power thus losing some low end torque has not been an issue, and it is very nice having the upper end range and increased top speeds.
     
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  5. Boss2083

    Boss2083 TMO Intermediate

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    Thanks, I’m just wanting to run maybe a couple times a month. Going all bolt ons (tune) I am a beginner drag in the drag racing scene I ran my cobra some I know she woke up with the 4:10s so I was just wanting some advice on the boss cars and how they are running and what you guys have done. Thanks
     
  6. ls110

    ls110 John

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    Great point raised that you are dragging versus road course and thus a very different need. Likely having that low end torque is important. I am on the other end of the spectrum and do not care about the launch.
     
  7. Boss2083

    Boss2083 TMO Intermediate

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    I understand I just have always been around drag racing since high school driving my 70 mustang. Just want a little wisdom from some guys who do it in there Boss. I know that 99 percent of the guys on here road race I just never had no one to teach me. (No tracks near me) I have a quarter mile strip 10 miles from me plus racing every weekend. So that’s the route I’m want to take with my Boss.
     
  8. Swine

    Swine TMO Intermediate

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    I would be more concerned with the gearing of your rear tire in conjunction with your gear ratio and expected trap speeds.

    In other words i would gear to it where you were just starting to hit the limiter going through the traps in 4th. Unless you want to make that 5th shift and lose time and mph which you will have to do in a super short ratio of a 4.11. Im sure it would feel fun on the street though.
     
  9. Speedboosted

    Speedboosted TMO Intermediate

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    I would figure out how much power you PLAN to have, and what gear you want to cross the traps in. The MT-82 has very short internal ratios, so 4.10 in your Cobra is really like 3.55 in the Boss. Shifting takes time, remember that, no matter how good you are.

    What mph do you trap right now and what gear/rpm when you cross the line?
     
  10. blacksheep-1

    blacksheep-1 TMO Addict

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    The fast guys around here in 4 cam fords are running 4.56 at the drags, the blower guys are running 3.90s, My gt500 went went 12.64 with 3.31s.
    I'm thinking a 3.90 to 4.10 would be fine for 90% of the road courses out there with a normally aspirated car.
     
  11. Mad Hatter

    Mad Hatter Gotta go Faster

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    I surprised!! I was looking at going 3.55 or 3.31 for road course use to avoid using fifth so soon. Maybe its because of my 25.3" diamter wheels though....
     
  12. Swine

    Swine TMO Intermediate

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    the 3.55 was money in my previous s197 on 275/40/18^2 revving to 7400.
     
  13. blacksheep-1

    blacksheep-1 TMO Addict

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    I'm thinking 3.90 to 4.10 would be about right. I'm thinking....thinking...really hard..thinking
     
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  14. 2012Boss302

    2012Boss302 TMO Addict

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    This.

    When I was drag racing we always tried to gear for crossing the line around peak HP rpm in a 1:1 gear.
     
  15. blacksheep-1

    blacksheep-1 TMO Addict

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    actually, just past it, that's why the mph trap is different from the ET trap..or was, when I was doing it
     
  16. APEXRaceParts

    APEXRaceParts Race Proven, Street Approved

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    We all need to remember the vast differences of the internal trans ratios between the MT-82 and TR-6060/T56. The MT-82 has a 1-1 ratio in 5th gear with a single overdrive where the 6060 uses 4th for 1-1 with a double overdrive. All else being equal, 3.31 paired with an MT-82 is about the same as 3.90 with a 6060.

    Then, of course, we need to consider the differences of the powerband and rev range. Do not spin a GT500 motor past the factory limiter of 6250 if you want it to live a long life. Coyote, on the other hand, doesn't seem to care about revs, so adjust rev limit based on what intake manifold you run.

    The last piece to remember is that shifting takes time, so while 4.10s feel fast, if it means you have to constantly shift or put you across the traps below peak power, you're making yourself slower.

    Take it for what you will, but here are my recommendations for a coyote in a drag race with a 28" rear tire. N/A: 3.73 to 4.10. 500-700 hp: 3.55. Over 700 hp: 3.31
    For a GT500: 450-650 hp: 4.10. 650+ hp use 3.73 as 4.10 will rev too high for a stock motor.

    On the road course and assuming a 26-27" tire, I like 3.31 or 3.55 for any coyote car, regardless of power level. For a GT500, I like 3.55 regardless of power level (would even consider 3.31 if it makes a lot, over 800 hp or so).

    - Cory
     
    Last edited: May 18, 2018
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