Gear Ratio
#1
NewHi. I'm building a 400hp 351c for my 72 mach 1. what would be a good rear end ratio to use for power? i have the FMX transmission. Thanks
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#2
How do you plan to drive the car? In town only, on the highway some? With an auto trans and no overdrive, 3.50:1 is a popular ratio when you still want to do occasional highway driving. My older brother ran that ratio in a 69 Mach 1 with a 351W and FMX trans way back in high school. It seemed to be about lowest reasonable ratio to also do some highway driving.

Best Regards,
Mike
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#3
I have to agree with Mike...it all depends on how you plan on driving the car. If you are planning on putting highway mileage on your car then 3:50 or better yet 3:25 are better choices. If you are looking for more performance, a bigger smile, and less than good gas mileage, you can run 3:89's or 3.91. I opted for 3:89's in my car and have not been happier with the choice. It really depends on what your expectations of what you want out of the car.
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#4
+1 on those figures. I've heard of people running higher and lower, but then they run into problems.
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#5
For everyday driving and highway use I'd go with a 3.25:1 gear ratio.
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#6
I run 3.89:1 in my 69 Mach 1. But it's a manual trans and I only drive it in town. It's fun in town, but I wouldn't do highway driving with them.

I could see where a 3.25:1 is suitable for regular highway driving. Not as fun in town though.

Best Regards,
Mike
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