Are 355's my best option - Page 4 - Ford Mustang Forum
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Originally Posted by Jsm6melton View Post
My car has 3:15's. How much difference between the 3:73's?
Gear ratios are straight-forward math, no voodoo involved.

3.73 / 3.15 = 1.184 ; or about 18% increase.

That means that at any given engine RPM and transmission gear:
  • there will be 18% more torque reaching the rear wheels
  • the rear wheels will be turning 18% slower; meaning the car will be moving 18% slower

18% is significant / noticeable

18% more torque means it will feel quicker and more responsive. 18% slower means you have to run the engine 18% faster to travel at the same speed, which burns about 18% more gas. Your overall gas mileage won't go down that much though because there is a big mix of conditions in real driving.

Remember there is no magic; the engine is still producing the same torque and horsepower. With the change in gearing, each gear will run out quicker so you'll have to shift quicker and get into the next higher gear sooner.


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My car with 3.55 gears and 295/35/18 rear tires is near perfect to me. I wouldn't want any more, or any less gear. I have had a 3.27 geared 4.6, a 3.73 geared hci 302, and now this 3.55 geared coyote. If it makes you feel anything, I was going to swap the 3.73s out of the 302 and install 3.55s, but the car got totaled before I could. 3.55 f t w.

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Thanks for explaining that. I have a 16 GT with an auto. My buddy has a 15 with a manual and trackpack with 3:73's. My car always pulls atleast a car between 95-100. Is the auto just inherently quicker than the manual with high gears or do you think its just driver error?
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Quote:
Originally Posted by Jsm6melton View Post
Thanks for explaining that. I have a 16 GT with an auto. My buddy has a 15 with a manual and trackpack with 3:73's. My car always pulls atleast a car between 95-100. Is the auto just inherently quicker than the manual with high gears or do you think its just driver error?

I would put money on the auto being faster unless your buddy knows that car like the back of his hand and quick shifts/power shifts it like an artisan.
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I personally decided to stay with my 3:31 gears. As they are optimal for top speed. If i ever take my car racing for a mile i would like to know that my top end is not hurt but shorter gears.

Think about how often you get a chance to drive top end vs how often you get to enjoy improved acceleration on a freeway on ramp.


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I ran the 3.55 on my '87 for about twelve years. I loved the response. These are a great combination of performance, drivability and traction.

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Originally Posted by stevegt2012 View Post
Think about how often you get a chance to drive top end vs how often you get to enjoy improved acceleration on a freeway on ramp.


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3.31 seems like the best rear end ratio for the MT82 to me also, but not because of top speed. These cars will never hit the theoretical top speed in 6th gear anyway, they are limited by the speed limiter and/or drag long before that. There are some situations where you might hit slightly higher top speed with 3.31's in 5th gear than 3.73's in 6th gear . . . . but that is at some very high speed like 150+ MPH anyway, and who really goes that fast? Unless on a road track with a really long straight, nobody.

The 3.31's just work out to a better overall range of gears for overall driving -- I see no need for a steeper first gear, and it gives you a fairly tall 6th gear for highway cruising.

On the on ramp or the highway, you can just downshift, unless you are already pushing 7,000 RPM, which I doubt.
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Having a manual and 3.55 gears, I find I start a lot from 2nd gear, especially doing the slight rolling stops. My combo is still stock but I feel that if I had 3.73's then 1st would be almost useless given how quickly I have to shift to 2nd already. I can imagine just how much worse it would be with more power. The engine stock already has more than enough power to max anything you could put to the tires in 1st gear. So for me I wouldn't go to 3.73's as I don't think I could shift the MT82 fast enough to make it anything but slower than with 3.55's. I know there are a lot of opinions about what is best, but for me the 3.55's seem the best ratio for power whether stock or modified. Plus I still get over 24MPG at 75MPH, more if I keep it legal..........

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This topic can go on forever and a gear change is something you only want to do once usually if you are not a mechanic and are not rich We prefer a 3.73 in the N/A cars, it is best for street, strip, daily drivers, and you will still get good mileage. We see 23-25 highway no problem.
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Quote:
Originally Posted by candersen View Post
Having a manual and 3.55 gears, I find I start a lot from 2nd gear, especially doing the slight rolling stops. My combo is still stock but I feel that if I had 3.73's then 1st would be almost useless given how quickly I have to shift to 2nd already. I can imagine just how much worse it would be with more power. The engine stock already has more than enough power to max anything you could put to the tires in 1st gear. So for me I wouldn't go to 3.73's as I don't think I could shift the MT82 fast enough to make it anything but slower than with 3.55's. I know there are a lot of opinions about what is best, but for me the 3.55's seem the best ratio for power whether stock or modified. Plus I still get over 24MPG at 75MPH, more if I keep it legal..........
3.55s in mine too. Also start a lot from 2nd gear. I'm really happy with the 3.55s
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