Gear Ratio Change

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  1. #1

    Default Gear Ratio Change

    I have a 2004 Mach One with a automatic. I would like to change the rear gear but don't know what is best. I have done a search and cannot find the info I need. So I am asking what do you guys think. I thought about 3:90 or 4:10 I live in Florida where the driving is more open then city. As far as bolt on stuff I have a drop in K&N, Magnaflow cat back. Down the road maybe headers, canned tune, intake spacer and torque convertor. What you think? What would my rpm's be at 60 and what convertor stall would you use? It's not a racer I just want to hold my own against my son who is giving me lip. He has a 2010 L-99 automatic SS Camaro with headers, canned tune, cai. I know I can't win I just want to get some respect!!

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    Senior Member Array TOYGT02's Avatar
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    First off, if you put gears in it you will need a tune. If not the speedo will be way off and the transmission will shift very erratic. If your Mach 1 was mine I would go with 3.73's and a 3200 Precision Industries converter. I had that conbo in my car once and it was best overall. It ran just as good, got better mileage, and I will go back to a 3.73 eventually. When you put gears in it buy a Detroit Tru-trac in it. Best $450 I've spent. Almost everyone I know with a Mustang has one. Good luck with the mods and go have fun racing your son.

    - - - Updated - - -

    With 4.10's at 65 I'm at 2500 rpm and it goes up quickly from there, you don't want to cruise 80. With the 3.73's I think it was about 2200 at 65.

  4. #3

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    thanks for the reply what about 3:90? everybody just skips the ratio and goes straight to 4:10 Everybody just talks about a 5 speed. The 3:73 are good but it's only one gear set up I don't know if it pays to do it what you think? I thought about the converter thought about a 2800. Have you ever put headers on this 4.6? What you think of the intake spacer for $100? Any mods I should do like the head cooling mod etc. I wish I could pick your brain!! I don't want to go to crazy my wife drives this more then me and you know how they can be. I have the 68 big block camaro.

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    Senior Member Array TOYGT02's Avatar
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    When my car was naturally aspirated I went from a 3.73 to a 4.10. It felt faster but actually ran slower in the 1/8. I have stayed away from the 3.90 because it is not a ford gear. I was told that they are noisier than the ford gear. I wouldn't give any consideration to a converter less than a 3200. I have a friend that went with a 2800 and eventually took it out for a 3500.

    Headers are A LOT of work and money for minimal gain. That's just my opinion.

    My wife still drives my car.

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