Questions on rear gear swap?

paluka21 · Jul 7, 2017

Turbo98GT said:
3.73 are bad for 1/2 miles

Why would a 3.73 rear gear be bad for a 1/2 mile? If you're running stock 3.31 gears you will be required to shift into 4th gear by 135mph, and with a 3.73 you'll just be shifting into 4th a bit earlier, albeit the rpms will drop less during the 3-4 shift keeping the car in a more optimum power band.
Just curious why you said they're not good for 1/2 miles?

kwhodson · Jul 7, 2017

10GT500 said:
Im running 305/35 MT SS's (28.7" OD). I have 3.73s and was thinking of bumping up to 4.10s due to the tire height. Whats everyone's thoughts on that?

I am in the same boat...I am probably going to put the 4.10s in. My friend has them with a 28.7" tire and I think the car just feels better.

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Jam421 · Jul 7, 2017

I also have the 305x 35's and 28.7" Tall MT's with 4.10's. That's approx 3.90 gear ratio which is perfect for me. 70-80mph is 1900-2100rpm on highway, with a 2.4 upper the gears jump into boost instantly, dead hooks from 15-30mph in 2nd . I've seen 130-135mph at top of 4th gear which is faster than I'd ever need to go when playing around on a highway . I had 373's after 2 power upgrades (both new sets) and both times the whine simply drove me crazy especially during quieter cruises 2000-2300rpm. The 4.10's are quiet at cruise...they rock on any quick roll burst on the street and I can use 6th gear on most highway trips.
Of course....there's no way I'd choose 4.10's for the 1/2 mile and tire height might play a role in 373 vs 355's.

Turbo98GT · Jul 7, 2017

paluka21 said:
Why would a 3.73 rear gear be bad for a 1/2 mile? If you're running stock 3.31 gears you will be required to shift into 4th gear by 135mph, and with a 3.73 you'll just be shifting into 4th a bit earlier, albeit the rpms will drop less during the 3-4 shift keeping the car in a more optimum power band.
Just curious why you said they're not good for 1/2 miles?

3.31s will go to 170-180mph depending on rear tire size and rpm. 3.73 will force you to shift into 5th gear around 155 mph and since it's an overdrive gear, the load on your engine goes way up and your speed goes down due to the gearing.

biminiLX · Jul 7, 2017

Jam421 said:
I also have the 305x 35's and 28.7" Tall MT's with 4.10's. That's approx 3.90 gear ratio which is perfect for me. 70-80mph is 1900-2100rpm on highway, with a 2.4 upper the gears jump into boost instantly, dead hooks from 15-30mph in 2nd . I've seen 130-135mph at top of 4th gear which is faster than I'd ever need to go when playing around on a highway . I had 373's after 2 power upgrades (both new sets) and both times the whine simply drove me crazy especially during quieter cruises 2000-2300rpm. The 4.10's are quiet at cruise...they rock on any quick roll burst on the street and I can use 6th gear on most highway trips.
Of course....there's no way I'd choose 4.10's for the 1/2 mile and tire height might play a role in 373 vs 355's.

I agree with all of this.
Really depends on your use of the car.
If you're willing to run a drag radial and actually drag race, the tall DRs and 4.10s are the best strip choice.
For more street guys I recommend 3.73s, but either way, a gear swap if done right, does not whine and greatly improves the car.
I've gone 3.31 to 4.10 to 3.73 and back to 4.10. Car ran better at track trap speed 4.10s vs 3.73
As above, use FRPP gears and good luck on a great installer.
-J

07 Black Beauty · Jul 10, 2017

I installed 3.73's on my 14 about a year and a half ago. I have had no issues w/ gear whine, although I did have a bearing go bad but the dealership that handled the install replaced it under warranty. For me the 3.73's are perfect as I DD my car and they make it much easier to drive. I haven't noticed much if any difference in mpg and as you stated no one guys these cars for fuel economy. If you do go with the 3.73's get a reputable shop to do the install because setup will determine if you end up w/ noisy gears. Also make sure to purchase the proper bearing for the 13/14's, the normal install kit includes the bearing for the 07-12 cars. Lethal sells the install kit minus the bearing and then you just purchase the proper 13/14 bearing separately.

biminiLX · Jul 10, 2017

07 Black Beauty said:
I installed 3.73's on my 14 about a year and a half ago. I have had no issues w/ gear whine, although I did have a bearing go bad but the dealership that handled the install replaced it under warranty. For me the 3.73's are perfect as I DD my car and they make it much easier to drive. I haven't noticed much if any difference in mpg and as you stated no one guys these cars for fuel economy. If you do go with the 3.73's get a reputable shop to do the install because setup will determine if you end up w/ noisy gears. Also make sure to purchase the proper bearing for the 13/14's, the normal install kit includes the bearing for the 07-12 cars. Lethal sells the install kit minus the bearing and then you just purchase the proper 13/14 bearing separately.

Just out of curiosity, what rear wheel/tire do you run?
-J

07 Black Beauty · Jul 11, 2017

biminiLX said:
Just out of curiosity, what rear wheel/tire do you run?
-J

11" 13/14 SS wheels w/ 295/35/20 MPSS

Questions on rear gear swap?

paluka21

Well-Known Member

kwhodson

Member

Jam421

Jam421

Turbo98GT

Mod Motor Mustangs

biminiLX

never stock

07 Black Beauty

Well-Known Member

biminiLX

never stock

07 Black Beauty

Well-Known Member

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