Gear swap?!?!

Badaz01

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Hi folks in a few days I’m gettin my entire irs/rear end redone. About a year now ago I had 373’s installed and the extra pep from those was nice but would’ve liked little more pull. So I was pondering going with 410’s while all the labor of taking down the irs is done while rebuilding the bushings. This will save me about 6-700 dollars if I do the gear swap then. I plan on boosting the car down the road will 410’s be ok doing that? On a side note if the 410’s are as good as I’ve researched I just may for go boosting and save around 10k and hopefully be satisfied with the new found low end power. Any experience or input on this would be appreciated.
 

01yellercobra

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If you're not sure about the blower down the road I'd go 4.10's now. Depending on the power level they can be made to work with some suspension work and good tires.

I had 3.90's in my 01 with T-56 and a decent amount of power. They were fun. But I hated them at freeway speeds. Mostly because they put the cruising RPM right where my BOV made the most noise.
 

Badaz01

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If you're not sure about the blower down the road I'd go 4.10's now. Depending on the power level they can be made to work with some suspension work and good tires.

I had 3.90's in my 01 with T-56 and a decent amount of power. They were fun. But I hated them at freeway speeds. Mostly because they put the cruising RPM right where my BOV made the most noise.
Thanks for the input. I’m also considering a custom short runner intake and I would imagine the shorter gear putting me into the high rpm power early would be beneficial for that.
 

Dirks9901

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Depends on the power adder. Imo 4.10’s are perfect for these cars with a centri. Not sure about a roots style blower. If it were me, i would also do the bushings and the BF irs brace or FR cover while its out.

I loved my 4.10’s NA and after i put a centri on. Make sure and put a decent tire on the car.


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Badaz01

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Depends on the power adder. Imo 4.10’s are perfect for these cars with a centri. Not sure about a roots style blower. If it were me, i would also do the bushings and the BF irs brace or FR cover while its out.

I loved my 4.10’s NA and after i put a centri on. Make sure and put a decent tire on the car.


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Yea man I have the Ford racing diff cover from the last time and I am getting the brace this time around. Kinda nervous about the 410’s hopefully I won’t regret it.
 

P49Y-CY

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i went from 4.10's back to 3.55's in my terminator because i do a lot of highway driving and it was too much rpm all the time. helped with the quarter mile times though! went through the traps at right about 6500 in 4th gear

i have 3.73s in my slightly heavier vert though, and they are perfect.
 

01yellercobra

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i went from 4.10's back to 3.55's in my terminator because i do a lot of highway driving and it was too much rpm all the time. helped with the quarter mile times though! went through the traps at right about 6500 in 4th gear

i have 3.73s in my slightly heavier vert though, and they are perfect.
I'm planning on sticking with the 3.55's. They're a good all round gear for the torque the 03/04's make IMO.

My 01 was a different animal. Big cubes and a big centri gave it a top end pull. But I think it would have done better with 3.73's or 3.55's towards the end.
 

shurur

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Yup..the general rule is 3.27-3.73 is best for power adders, while 3.9-4.56 is for NA.

I got 3.73 because I had plans for a procharger, now that I know I plan to stay NA I wish I had gone 3.9+.

The shop actually talked me out of going 3.9 in favor of 3.73.
I also went to a Detroit true track at that point as well.
 

omj

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I have a 99 with a Vortech and 4.56s. It's perfect for stock internal power. When my new motor is installed, I'll probably step down to 4.10s since I'm expecting to make 700+
 

Badaz01

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Cool I think I’m gonna go ahead and swap my 373’s with 410’s because I want the down low pep while still na and would like to leave some drivability for a centri blower down the road.
I have a 99 with a Vortech and 4.56s. It's perfect for stock internal power. When my new motor is installed, I'll probably step down to 4.10s since I'm expecting to make 700+
 

FIREBALL

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I had gone from the stock 3.27 to 3.73 and that didnt work out for me. The 3.73s when it came to cruising didnt work it was either too high or too low for what ever gear I was in. Ive described it in the past as putting me in no mans land. I went back to my stock gears as I didnt want to pay for another set of gears. I think 3.55 would probably be the best, but you should be happy with the 4.10s and will probably be better than 3.73s
 

01ssnake

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Hi folks in a few days I’m gettin my entire irs/rear end redone. About a year now ago I had 373’s installed and the extra pep from those was nice but would’ve liked little more pull. So I was pondering going with 410’s while all the labor of taking down the irs is done while rebuilding the bushings. This will save me about 6-700 dollars if I do the gear swap then. I plan on boosting the car down the road will 410’s be ok doing that? On a side note if the 410’s are as good as I’ve researched I just may for go boosting and save around 10k and hopefully be satisfied with the new found low end power. Any experience or input on this would be appreciated.

4.10 is minimal on these cars. That’s if your going for serious power. Remaining N/A go 4.30 or 4.56 only nothing more nothing less. I went straight from 3.27 to 4.56 and love it , it’s perfect. If you want to tame it a little you can go from stock 25.5 tires to 26.5 or 27 inch tires . No reason you’ll ever want less then 4.56 after putting them in
 

Badaz01

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4.10 is minimal on these cars. That’s if your going for serious power. Remaining N/A go 4.30 or 4.56 only nothing more nothing less. I went straight from 3.27 to 4.56 and love it , it’s perfect. If you want to tame it a little you can go from stock 25.5 tires to 26.5 or 27 inch tires . No reason you’ll ever want less then 4.56 after putting them in
Thanks for the input I am currently running 295 40 18 nitto 555g2 on rovos they made my 373’s dog out and I may boost later on but want the extra pep until I do so.
 

01ssnake

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Thanks for the input I am currently running 295 40 18 nitto 555g2 on rovos they made my 373’s dog out and I may boost later on but want the extra pep until I do so.

4.30 or 4.56 brother for sure. 3.73 make almost no difference from 3.27 stock. You gotta really hit 4.10 to make a difference and even that’s small. Honestly 4.10 if came from factory would of been perfect.
 

coposrv

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Hi folks in a few days I’m gettin my entire irs/rear end redone. About a year now ago I had 373’s installed and the extra pep from those was nice but would’ve liked little more pull. So I was pondering going with 410’s while all the labor of taking down the irs is done while rebuilding the bushings. This will save me about 6-700 dollars if I do the gear swap then. I plan on boosting the car down the road will 410’s be ok doing that? On a side note if the 410’s are as good as I’ve researched I just may for go boosting and save around 10k and hopefully be satisfied with the new found low end power. Any experience or input on this would be appreciated.

Depends on your trans too. A t45 is 3.37 a 3650 is 2.9? I think and t56 is 2.66


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01ssnake

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Depends on your trans too. A t45 is 3.37 a 3650 is 2.9? I think and t56 is 2.66


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3650 is also a 3.37 first gear. T56 in terminator is 2.94 first. Car revs to 6700 rpm, even with the shorter 1st gear when N/A on stock height tires it’s fine with 4.56, 4.30.
Start running more power like boost go from stock height tire 25.5 to 27 or 28 to tame the gear. No reason to swap gears or run anything less
 

01ssnake

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03-04 Cobra T56 is 2.66:1.

wow , I knew the 00 cobra R t56 had 2.94 first ratio and I had a 2005 GTO with T56 2.94 as well. Didn’t think Tremec built T56 with a different ratio , unless you did the Magnum. 2.66 is a real dog of a ratio!
 

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