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Discussion Starter · #1 ·
2004 mustang gt with the 5 speed and 73,000 miles
its my daily driver so i dont wanna lose my mpgs lol the few that it has i live in ca where gas is like 4.00$ a gallon.. i see a lot of traffic stop light to stop light and a a decent amount of 55-70mph.. im tired of getting beat by new cars to lol so im turning to gears. i have the 3.27 gears in the good old 8.8
whats the best gear ratio thanks for the help guys
 

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Anandavenkatakrishnan
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go buy a used centri blower. You'll barely be in boost unless you're trying too. Then when it's time to put the hammer down, the car will fly

If budget does not allow, go with 3.73s
 

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welcome to MM

373 gears.
 

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2004 mustang gt with the 5 speed and 73,000 miles
its my daily driver so i dont wanna lose my mpgs lol the few that it has i live in ca where gas is like 4.00$ a gallon.. i see a lot of traffic stop light to stop light and a a decent amount of 55-70mph.. im tired of getting beat by new cars to lol so im turning to gears. i have the 3.27 gears in the good old 8.8
whats the best gear ratio thanks for the help guys
Gears can actually help mileage in drivers who are in your situation. Unless your constantly cruising at 75-80, 3.73s won't hurt you much, if at all, at the pump. I think 3.73s would be good for you. Then save up for a centri.
 

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Discussion Starter · #6 ·
are 4.10 to much heard 373 are not enough to notice when u already have 3.27
 

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I live in California and I'm not sure where you are getting gas but you should get a Costco card, I've been paying about 3.60 for premium. I have 4.10s and would do nothing less. I want to go 4.30s and drive the freeway every day and get about 23mpg hi way.


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Well if you plan on going forced induction in the future, 4.10s are overkill. You'll be spinning through 2nd.

Anyways, you WILL notice 3.73s. I definitely recommend you read through those threads. Plenty of wisdom to go around on these forums.
 

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With the T-45 in your 2004, you should have a .62:1 fifth gear.
That said, I'd say the 3.73's should be ideal for you. They'll rev up quicker in each gear, giving you more usable torque, and allowing you to "short shift" should you feel the need. In stop/go traffic, you'd like them better, and when you get on the freeway, you'll accelerate quicker. The other benefit is the .62:1 fifth gear gives you the same effective ratio with the 3.73 gear that the earlier t-5 with the .67:1 5th had, so you'll not really lose any highway mpg, at 70mph you'd be just above 2000rpm, and at 55 you'd be around 1700. That's a lot easier on the motor than the 1500 or so you were at on the 3.27's with the .62:1 gear as you're not lugging it where it's got no torque.

Try em out, I think you'll like them.
 

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4.10s are wonderful in traffic. I do a mix of highway/city. I gained mpg with my 4.10
 

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With the T-45 in your 2004, you should have a .62:1 fifth gear.
That said, I'd say the 3.73's should be ideal for you. They'll rev up quicker in each gear, giving you more usable torque, and allowing you to "short shift" should you feel the need. In stop/go traffic, you'd like them better, and when you get on the freeway, you'll accelerate quicker. The other benefit is the .62:1 fifth gear gives you the same effective ratio with the 3.73 gear that the earlier t-5 with the .67:1 5th had, so you'll not really lose any highway mpg, at 70mph you'd be just above 2000rpm, and at 55 you'd be around 1700. That's a lot easier on the motor than the 1500 or so you were at on the 3.27's with the .62:1 gear as you're not lugging it where it's got no torque.

Try em out, I think you'll like them.
04s are a 3650, not T45

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are 4.10 to much heard 373 are not enough to notice when u already have 3.27
They are enough to notice. I went from the factory gears to 3.73s prior to my blower install and you can notice it as long as one doesn't get into all the hype behind a gear change that give some ppl unreasonable expectations.
 

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Anandavenkatakrishnan
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OP, you will definitely notice the change from 3.27 to 3.73. However, the change will not be as different from the change from 3.27 to 4.10.
 

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Gears will help you get moving, but they don't add any hp. If you want to be faster than newer cars get a blower. If you have to get gears, 3.73s are a pretty good choice but to make the most of them get a decent pair of tires out back along with some suspension work. That will get you off the line pretty well, but won't help you on the highway.
 

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I posted something similar in another thread just yesterday. There are thousands of gear threads that all say much the same thing.

3.73s are 14% lower than stock 3.27s. 4.10s are 25% lower. If you are running at 2000 rpms with stock gears that same speed would be 2280 rpms with 3.73s and 2500 rpms with 4.10s. At 4000 rpms with stock gears that same speed would be 4560 with 3.73s and 5000 rpms with 4.10s. That's an increase of 500-1000 rpms depending upon your speed.

Talking highway gas mileage is more complicated than just throwing out a number. There are four different transmission all with different overdrive gear ratios. Autos have a .70:1 overdrive. T-45s have a .67:1. The 2001 T-3650s have .68:1. Later T-3650s have a .62:1. An auto with 3.73 gears will be running at higher rpms down the highway than a later T-3650 with 4.10s. A T-45 with 3.73 will run about the same rpms as a 2002-2004 T-3650 with 4.10s.

Gas mileage really isn't as big an issue as everyone makes out. Yes, you will loose 2-3 mpg. I have a T-45 transmission. I lost 2 mpg when I had 3.73 gears installed going from 22 mpg to 20 mpg on my daily commute. At the time I was driving 500 miles per week. At $4.00 per gallon my gasoline cost before gears would have been $90. After gears it was $100. You have a T-3650. If you put in 4.10s then you would have similar results.

On the street traction starts becoming a problem with lower gear ratios as horsepower increases. We are not be running heated slicks on a prepped surface. Most of the guys running superchargers go with 3.73 gears. As horsepower increases they go up to even higher gears such as 3.55s and stock 3.27s.

They go to higher gears for the dragstrip as well to keep from running out of gear. That is when you redline before reaching the finish line. Not so much of a problem at eighth mile tracks but it can be a problem in the quarter. GTs redline is around 5800 rpms. If you are running a standard 245/45-17 sized tire with 4.10 gears without going into overdrive that would be a speed of 105 mph. Mach 1s and Cobras have an advantage here. Their redline is higher than a GTs so the speed at redline is higher.

You can water down the effect of lower gears a little by going to a bigger tire. Putting a 28" tire on the car with 4.10 gears is about the same as running 3.90s. This technique works well at the track because 28" slicks and ET Streets hook really well. Not really a good technique for the street.

Naturally aspirated autos are pretty much stuck with 4.10 gears because of the high first and second. They just have to suck it up on the highway and live with the higher rpms. The first four gears in our manual transmissions are the same. The main complaint with 4.10 gears is the very short first gear. Driving normally you are hardly rolling when you have to shift to second. This bothers some, not others. It has botherd some enought to pull the 4.10s and put in 3.73s.

The reason talking about gears creates a huge debate is that people have different power levels, different redlines, different transmissions and different uses.

Your transmission's higher overdrive gives you a little more flexibility than the generally accepted "3.73s for a manual and 4.10s for an auto." 3.73s would be a good gear but if you can stand the short first gear then 4.10s would be a good gear as well. You will probably need to run drag radials in the summer to get traction in first and second. If you plan on a power adder than I'd recommend 3.73s.
 

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Go 3.73s. I do mixed city and highway on my 04.

You will notice a difference between the stock 3.27s and 3:73s. Sticky tires will also help. What good is gears and additional power if you can't plant it. Sure spinning the tires is fun and all but not when you get left by the other car.
 

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3.73s for sure if its your daily.
 

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are 4.10 to much heard 373 are not enough to notice when u already have 3.27
2V GT: The GT reacts to gear changes much the same way a 5.0 does although the real problem is that they have less torque than a 302.


For stick cars I recommend 3.73 gears. The 3.73 gives an excellent increase in acceleration and top speed isn't decreased because you are able to wind out overdrive further. With a 3.73 your rpm in 5th gear at 60 mph will only be 2005, not at all what you might call "too high". As I said, your top speed will not decrease when putting lower (numerically higher) gears in a car with overdrive. You will simply wind out 5th gear further than you could with the higher gears (numerically lower).


For AODE cars, 3.73's are still a good choice but I recommend 4.10 gears. A 4.10 may sound extremely steep, but because the AODE's 1st gear is higher (numerically low) and 4th gear (overdrive) is steeper than the T-5, it's a very good choice for the driver interested in making their car perform better. But like I said earlier 3.73 will be great as well.


4V Cobra: The Cobra has an entirely different engine than most people are used to. It performs best at high rpms, upwards of 7000. It's power band is relatively high due to the deep breathing nature of the two intake valves. When gearing a Cobra, 3.73's just aren't enough. Though they are do-able and must people like what they have. But, They don't allow the engine to reach its power band quickly enough. 4.10 gears are an excellent choice and 4.30's are even better. This may sound very steep if you're used to the average 5.0 which needs to be shifted by 5600 rpm. But since this engine will easily rev to 7000 it needs the extra gear and it likes it.


Hope that helped :)

Source: Alternative Automotive
 
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