373 or 390 gears in a 2002 gt

Timothyeg

Member
Aug 23, 2020
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Hi everyone with stangs.I want to upgrade my gears.I want 373 or 390 gears,not 410s as I think they won't be that good for highway speed.My mechanic suggested 390s over 373s and said they would be a good middle between 373s and 410s.Do the 390s have better pick up and will I notice much say 0 to 60? Does anyone have any experience with 390s?I had 373s in my fox body but that was 20 years ago and I really don't remember how they were? Any suggestions would be great!
 
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Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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Honestly, if you drove two identical cars, but one with 3.73s and one with 3.90s, I doubt the average person would be able to tell a difference. Mod motors do rev higher than the ole pushrods, so they tend to like the shorter gearing. I’ve driven 4.6s with 4.30s and even 4.56s and liked it, although if you do a lot of higheay driving it will get old revving so high while cruising.

given your two choices, go 3.90 if you don’t want 4.10

3.27 to 3.73 is such a small junp it not worth the expense
 
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Timothyeg

Member
Aug 23, 2020
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Sayre pa
Honestly, if you drove two identical cars, but one with 3.73s and one with 3.90s, I doubt the average person would be able to tell a difference. Mod motors do rev higher than the ole pushrods, so they tend to like the shorter gearing. I’ve driven 4.6s with 4.30s and even 4.56s and liked it, although if you do a lot of higheay driving it will get old revving so high while cruising.

given your two choices, go 3.90 if you don’t want 4.10

3.27 to 3.73 is such a small junp it not worth the expense
Honestly, if you drove two identical cars, but one with 3.73s and one with 3.90s, I doubt the average person would be able to tell a difference. Mod motors do rev higher than the ole pushrods, so they tend to like the shorter gearing. I’ve driven 4.6s with 4.30s and even 4.56s and liked it, although if you do a lot of higheay driving it will get old revving so high while cruising.

given your two choices, go 3.90 if you don’t want 4.10

3.27 to 3.73 is such a small junp it not worth the expense
 

Timothyeg

Member
Aug 23, 2020
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Sayre pa
With 327 Gears I cam hit over 60 in 2nd gear.Would I be able to hit 60 in 2nd gear with 390s before shifting to 3rd? It seems counter productive to be faster out of the gate but have to shift 3 times instead of 2 unless you got there much quicker with 390s,then it would be a win situation.I may supercharge ,but want to really stay na.
 

Timothyeg

Member
Aug 23, 2020
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Sayre pa
4.10 or nothing. Dont fear the gear
Seriously I know 4.10s have a lot of pull but I don't want to shift every 2 seconds.I need something for all around driving and something with good take off to.That is why I was thinking maybe even 390s but not 410s.
 

Nightfire

15 Year Member
Dec 1, 2002
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Seriously I know 4.10s have a lot of pull but I don't want to shift every 2 seconds.I need something for all around driving and something with good take off to.That is why I was thinking maybe even 390s but not 410s.

The MPG difference is negligible. The performance difference is noticeable
 

stormsedge

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Jun 17, 2018
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My plan is 3.90s when I do mine...based on current tire height, and getting what would be 3.73 results with the OEM height tires. My dollar two ninety-eight.
 

Chipss36

New Member
Oct 9, 2020
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I think gearing needs to be set up with powerband in mind more than any other.
410s are great with a car that has more power on the top end, and is happy at higher rpm. but makes a stock motor flat out hard to drive.
3.75 have worked very well for me with a stage 2 ish , cam/heads Combo..

many have to go 410s with the the boss motor I am building now...has much more cam ...
I think in terms of the total build, what hp/trq , where the powerband is.
What do I have to do to support that...
Be it gears, fuel, intake, exhaust.
And the one thing I overlook, well it will be the thing that gets me.
 

Timothyeg

Member
Aug 23, 2020
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Sayre pa
I think gearing needs to be set up with powerband in mind more than any other.
410s are great with a car that has more power on the top end, and is happy at higher rpm. but makes a stock motor flat out hard to drive.
3.75 have worked very well for me with a stage 2 ish , cam/heads Combo..

many have to go 410s with the the boss motor I am building now...has much more cam ...
I think in terms of the total build, what hp/trq , where the powerband is.
What do I have to do to support that...
Be it gears, fuel, intake, exhaust.
And the one thing I overlook, well it will be the thing that gets me.
I may supercharge in the end but don't know for sure.If I do I hear 373s are the way to go.410s would be too much supercharged! I don't know for sure.The gears I ordered are now here so it looks like it's 373s.I hope I don't regret it?
 
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Timothyeg

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Aug 23, 2020
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I may supercharge in the end but don't know for sure.If I do I hear 373s are the way to go.410s would be too much supercharged! I don't know for sure.The gears I ordered are now here so it looks like it's 373s.I hope I don't regret it?
Does anyone know what the difference in 0 to 60 times are with 373 gears and the stock 327s?
 
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Nightfire

15 Year Member
Dec 1, 2002
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I dont know why I waste my time with threads like this. Ive been driving 4.6 mustang for almost 25 years. Yet noobs think that they know better. Shift every 2 seconds? Its times like this that I just want to see you waste your money and be disappointed. Makes me smile
 

Timothyeg

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Aug 23, 2020
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Sayre pa
So I am a noobie? I have had some stangs years ago.I bought this new edge almost 3 months ago.I had 373s in my fox body but don't recall exactly how they were because it was 20 years ago.373s would be a good choice for forced induction.410s have a lot off pull for sure,but 1st gear is almost useless unless you want to smoke the hell out of your tires! I want to be able to hook up in all my gears.If you read my post you would see that I am thinking about supercharging. 410s wouldn't be a good choice for that.Some people make it work.They like 410s and hell maybe I will try them if I get the itch to.
.
 
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Chipss36

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I dont know why I waste my time with threads like this. Ive been driving 4.6 mustang for almost 25 years. Yet noobs think that they know better. Shift every 2 seconds? Its times like this that I just want to see you waste your money and be disappointed. Makes me smile

you don’t even daily drive said stang do you?
So do you have 410 gears In the car you do drive daily?

bet not!
Did you even read the first post?
I had 410’s on a daily once, I was teen then though...I am now an old man. What hair I have left is pure white...
Ran the salt flats, ran top fuel Harleys
I been in this game awhile.
A mod motor still sticks to the same math, and the same physics as any other motor, it’s nothing special.


Best not to assume things guy!

3.75 are a decent “freeway ok” compromise.
I think the op will be happy with that choice...
If it becomes a track/bar hopper only car, And 15” drag tires later change it.
 
Last edited:

Nightfire

15 Year Member
Dec 1, 2002
3,374
195
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you don’t even daily drive said stang do you?
So do you have 410 gears In the car you do drive daily?

bet not!
Did you even read the first post?
I had 410’s on a daily once, I was teen then though...I am now an old man. What hair I have left is pure white...
Ran the salt flats, ran top fuel Harleys
I been in this game awhile.
A mod motor still sticks to the same math, and the same physics as any other motor, it’s nothing special.


Best not to assume things guy!

3.75 are a decent “freeway ok” compromise.
I think the op will be happy with that choice...
If it becomes a track/bar hopper only car, And 15” drag tires later change it.

Back when I had just a few bolt-ons you bet your ass I DD'd the car WITH 4.10's. It was a fkn blast to drive!
 

Chipss36

New Member
Oct 9, 2020
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Back when I had just a few bolt-ons you bet your ass I DD'd the car WITH 4.10's. It was a fkn blast to drive!
Sure ya did...
And you did not answer the question did you!
Let me refresh the question asked son.
Do you daily drive 410 gears?
its a rhetorical question anyway, I know the answer, it shows hypocrisy, and rudeness.

what ever dude..
typical mustang guy, no other group, is as rude, or opinionated than the internet’s mustang guys.

Glad you like 410’s on your track car.....
Next time loose the attitude.

we will all be better for it.
 

Nightfire

15 Year Member
Dec 1, 2002
3,374
195
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Sure ya did...
And you did not answer the question did you!
Let me refresh the question asked son.
Do you daily drive 410 gears?
its a rhetorical question anyway, I know the answer, it shows hypocrisy, and rudeness.

what ever dude..
typical mustang guy, no other group, is as rude, or opinionated than the internet’s mustang guys.

Glad you like 410’s on your track car.....
Next time loose the attitude.

we will all be better for it.

There's nothing rude about what I said snowflake. Do I daily the car now? Of course not. It has nothing to do with gears and everything to do with C85 fuel, slicks, and a locked diff. But then again WTF does my current setup have to do with the situation being discussed? I DD'ed the car 4.10 and bolt-ons for years. Talk about rude......dont EVER call me "son"
 

Dark04GT

10 Year Member
Apr 27, 2008
751
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59
NC
Everyone has a different opinion about gears. It is just math and picking what you are comfortable with:

Assuming stock tire height-
4.10’s: Top of 4th, 1/4 mile max trap = 117mph; 70mph cruising in 5th = 2,300rpm
3.90’s: Top of 4th, 1/4 mile max trap = 123mph; 70mph cruising in 5th = 2,150rpm
3.73’s: Top of 4th, 1/4 mile max trap = 128mph; 70mph cruising in 5th = 2,050rpm
3.27’s: Top of 4th, 1/4 mile max trap = 146mph; 70mph cruising in 5th = 1,800rpm

Comfort: 4.10’s vs stock 3.27’s means ~500 rpm difference at the highway speed limit - might make a comfort difference...end user dependent.

1/4 mile: 3.90’s and 4.10’s provide more ideal gearing for bolt on mustangs. 3.73’s and lower provide more trap speed for power adder cars (3.73’s would add more pep to a bolt-on car too and would be a decent compromise on comfort vs performance for a street car).

Personally - my car spends 99+% of the time on the street. I added a power adder rather than messing with gearing. Hehe. Everyone has a preference.