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Which gear?

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Old 08-25-2014, 01:28 PM
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mechanic58
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Question Which gear?

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Last edited by mechanic58; 08-28-2014 at 11:08 AM. Reason: Apparently no one on this forum is intelligent enough to provide input on this.
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Old 08-25-2014, 01:52 PM
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SSG Steggy
 
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I have performance pkg that came with 3.31's... @80mph cruise, I avg'd 26.4mpg on 350mile trip. 3.55's won't be much different. Maybe tach a little higher at 80, but not so much to lose that much mpg, yet still give a noticeable difference in low end pull.
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Old 08-25-2014, 03:00 PM
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mechanic58
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Old 08-26-2014, 10:19 AM
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What is your goal for the gear change; ie. quicker 0-60 & 1/4-mile, overall better low end pull, decrease in avg mpg?

And is your Premium stick or auto? Auto - recommend the 3.73 just to regain some of the loss from the powertrain, Stick - 3.55.
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Old 08-27-2014, 02:17 PM
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Old 08-27-2014, 04:30 PM
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I agree, 2.73 is definitely hwy gears, best fuel efficiency on long trips, low RPM's at Highway speeds. I was just suggesting that if you are not looking to drag race, like going with 4.10, then 3.73 would at least give you a good seat of the pants difference vs the 2.73's. For the comparable feel on takeoff, 3.55 in a stick would feel about the same as 3.73 in an auto due to loss of power caused by the drivetrain. Either way, you'll feel the difference coming from 2.73.
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Old 08-28-2014, 07:04 AM
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Old 08-28-2014, 07:48 AM
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Originally Posted by mechanic58
I think you got that backwards. You can always assume about a 10% taller final drive in automatic applications vs manual. Fact.

I don't do a lot of highway driving with this car. A 2.73 gear is entirely too tall for 80% of the driving I do. The car lugs around most of the time unless I manually downshift it out of high gear. I suspect, based on past experience, that lowering the final drive gear will actually increase my average gas mileage - not to mention give a more pleasing seat-of-the-pants feel on a launch.
Actually your the one that is wrong! This isn't 1965 anymore. I Posted a link below for the gear ratios by gear for a manual and an automatic 2014 mustang gt. Notice how the manual has the steeper final drive? I also posted the same information for the v6. Notice the final drives are exactly the same in the manual v6 as they are in the automatic v6! And finally your mileage will suffer by adding a steeper gear. That's why ford put the 2.73 in the V6 in the first place!

http://www.geigercars.de/fileadmin/i...tang_Specs.pdf

http://www.geigercars.de/fileadmin/i...ngGT_Specs.pdf

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Old 08-28-2014, 08:08 AM
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Originally Posted by bluebeastsrt
Actually your the one that is wrong! This isn't 1965 anymore. I Posted a link below for the gear ratios by gear for a manual and an automatic 2014 mustang gt. Notice how the manual has the steeper final drive? I also posted the same information for the v6. Notice the final drives are exactly the same in the manual v6 as they are in the automatic v6! And finally your mileage will suffer by adding a steeper gear. That's why ford put the 2.73 in the V6 in the first place!

http://www.geigercars.de/fileadmin/i...tang_Specs.pdf

http://www.geigercars.de/fileadmin/i...ngGT_Specs.pdf
Agreed, auto trans always needs a steeper gear set to gain the same kind of off the line performance as a manual.
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Old 08-28-2014, 08:28 AM
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Originally Posted by mechanic58
I have a set of 3.27 gears that came out of an 8.8 IRS axle that was in a Cougar. Basically the same gear as the 3.31. I'll never understand why Ford made those two ratios so close together. I have contemplated just using them since I already have them, but I suspect the 3.55s will work better. I'm hoping someone who already has them installed will chime in with some input.
it all depends on how they match the axle to the trans gear ratios and the engine power/torque curves.
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