GT automatic stock 3.15 or 3.55

[NavyChief]

I have 3.55 and at 65 mph my tach is at 2000. And the instant mpg says 25mpg. I only have 312 miles on her. I'll take that mpg anyday. I drove a 3.15 auto and did not like the thumb when you gave it gas and from what I have seen I am getting almost the same mpg as the 3.15 auto but have more fun. I miss my 4.10 in my old stang and when warranty is up I'll install them again. :cheers::cheers:

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[Eco-T]

Hope this hasn't been dead for too long... any input on where to upgrade my 3.15 to a 3.55? is this something my dealership can install before i pick her up? thank you

 

[15GTBEN]

Hope this hasn't been dead for too long... any input on where to upgrade my 3.15 to a 3.55? is this something my dealership can install before i pick her up? thank you

It is a factory option.

 

[Eco-T]

It is a factory option.

And if its a car already in the lot?

 

[15GTBEN]

And if its a car already in the lot?

You would have to have aftermarket gears installed by the dealer or by a speed shop. Not all dealers do gear swaps.

 

[Spartan]

I'm sure the 4.10's are fun but at the cost of horrible traction in 1st on street tires and highway mileage. Mike R himself has said that anything more than 3.31's with the 6R80 are negligible. It's the torque converter that holds the 60ft back.

OP, If mainly for daily driving, not plan on making big power and want a little extra kick in the pants get the 3.55's.

They don't offer the 3.31 in the auto in the GT, surprised they didn't put that option in there and instead put the 3.55. If that's true then 3.31 is all they needed.

 

[Quiksilver15]

I say go drive both before making a decision. I did, and I instantly knew I couldn't live without the 3.55s. The extra kick down low puts a smile on my face daily

 

[craigsix]

No worries...

I was bored again this morning.

city 3.15 & 3.55- 16MPG
highway 3.15- 25MPG & 3.55- 23.5MPG
total 100,000miles. 50% highway miles cruising in top gear.

city- 50,000miles/16MPG=3,125gal.
highway- 50,000/25=2,000
5,125x$3= $15,375
or
city- 3,125gal.
highway- 50,000/23.5=2,128
5,253x$3= $15,759

$384 more per 100,000miles @ $3/gal

i get 29mpg at 65mph with 3.15 cruise control

 

[Old 5 Oh]

i get 29mpg at 65mph with 3.15 cruise control

Me, too. But I know guys are getting 26 with the 3.55s. So his math is close. It's not a big dollar difference.

 

[danny0441]

for me 3.55 were a must i went with the factory 2.73 wth my 2014 v6 and hated the way the car drove and figured the auto 3.15 would not be as enjoyable im sure im wrong but upgrading after market runs easily 700 bucks from factory 395 well worth it i didint buy my 5.0 for fuel economy

 

[sigintel]

Bump for jimdohc chart for gearing!
Thanks dude your post is sticky worthy alone.

My worthless opinion:
3.15 for 6R80 with power adder strip, street or track
3.55 for 6R80 for 18" hoonage on street if you like fishtailing alot and playing with back end out.
3.15 for 6R80 for those wanting quieter cruise and taking work calls on highway.
3.55 for 6R80 if going to much wider tires and tracking

 

[Gdyup50]

SO I saw that 3.15 was suggested for a SC car, mine came with the 3.55 and I'm getting ready to go with either a Paxton or a KB setup. What's the major difference between gearing for these? Thanks

 

[Higgs Boson]

SO I saw that 3.15 was suggested for a SC car, mine came with the 3.55 and I'm getting ready to go with either a Paxton or a KB setup. What's the major difference between gearing for these? Thanks

dont worry about it, you will be fine. 3.55 are not aggressive gearing, 3.15s are for gas mileage. enjoy your car.

 

[2015 Silver GT]

3.15s are for gas mileage.

My best with just some bolt ons was 11.2 with 3.15's. So they're not just for gas mileage.;)

 

[Higgs Boson]

My best with just some bolt ons was 11.2 with 3.15's. So they're not just for gas mileage.;)

even a honda civic can run 7's....just add power.....doesn't make it an ideal platform.

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