3.55 gears make much difference over 3.31?

I have a manual tranny '18 eb with the 3.31 gears, non-pp. I bought ford racing 3.55 gears because they were cheap but now having second thoughts about hacking into my brand new car's differential, plus looks like the intal kit cost more than the gears did.
Does anyone know if the 3.55 gears make a noticable difference? Might be hard to tell because I don't think there's an abundance of manual trans eb without pp, and the a10 is 3.15 I think but wondering if anyone had test driven a pp back to back with a 3.31 non pp...

Also wondering if the stock differential is "torsen" or if it's not limited slip like the pp, even if I upgrade the gears?

Im going to be honest with you, I switched out my 3.31s for 3.55s when I had to have my diff rebuilt so I figured I would go up a gear (so to speak) and no the difference is not that huge, it is not like we are coming from 2.73s which would be a hike of a difference. You will notice a difference for sure because its a different ratio but its just going to increase your rpms on the highway, lower your MPG by about 1-3 mpg (your miles may vary) but its not a mind blowing difference.

So in my opinion unless you have to do it, I would not go with anything but 3.73s if you are coming from 3.31s. If you were an auto I would go with the 3.55s.

Huge difference. Makes the car more driveable on highways/freeways, too (6th is actually useable around 55 MPH) I test drove both, and it swayed me to the dark wheel side (Performance Pack...)

ElAviator72 said:

Huge difference. Makes the car more driveable on highways/freeways, too (6th is actually useable around 55 MPH) I test drove both, and it swayed me to the dark wheel side (Performance Pack...)

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Well yeah it will make 6th gear a hair more usable, that is true. Not alot of upside if your diff is in good shape no need in the MT to upgrade.

5.0yote said:

Well yeah it will make 6th gear a hair more usable, that is true. Not alot of upside if your diff is in good shape no need in the MT to upgrade.

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More than that. With the MT, acceleration is definitely snappier with the 3.55...

ElAviator72 said:

More than that. With the MT, acceleration is definitely snappier with the 3.55...

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You'll get more torque to the dirve wheels in each gear, which equates to snappier acceleration, but your zero-to-sixty time will likely suffer because you can get to sixty in second gear with the 3.31 rear end and a manual tranny. You have to upshift to third to reach sixty with the 3.55. If you're road racing the 3.55 gears are the way to go. For everyday driving the taller 3.31 gearing makes better sense to me, primarily because I value this car for its efficiency. I wouldn't want to give up the fuel mileage.

TorqueMan said:

You'll get more torque to the dirve wheels in each gear, which equates to snappier acceleration, but your zero-to-sixty time will likely suffer because you can get to sixty in second gear with the 3.31 rear end and a manual tranny. You have to upshift to third to reach sixty with the 3.55. If you're road racing the 3.55 gears are the way to go. For everyday driving the taller 3.31 gearing makes better sense to me, primarily because I value this car for its efficiency. I wouldn't want to give up the fuel mileage.

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If you're looking to build a drag car, you want an automatic anyways...no one is competitive on the drag strip anymore with a manual :doh:

ElAviator72 said:

If you're looking to build a drag car, you want an automatic anyways...no one is competitive on the drag strip anymore with a manual :doh:

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True, but 0 to 60 time is also a pretty good indicator of everyday drivability because it's a good indicator of how quickly can you get up to highway speed.

If getting the most power to the ground at all times in every gear is the most important consideration, then get the shorter gears. IMHO, however, the taller gears make more sense for a daily driver. To each his own brother!

I like my 3.15s, even my buddy wants them for his 800+hp JPC turbo 2016 GTCS
:first:

5.0yote said:

Im going to be honest with you, I switched out my 3.31s for 3.55s when I had to have my diff rebuilt so I figured I would go up a gear (so to speak) and no the difference is not that huge, it is not like we are coming from 2.73s which would be a hike of a difference. You will notice a difference for sure because its a different ratio but its just going to increase your rpms on the highway, lower your MPG by about 1-3 mpg (your miles may vary) but its not a mind blowing difference.

So in my opinion unless you have to do it, I would not go with anything but 3.73s if you are coming from 3.31s. If you were an auto I would go with the 3.55s.

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AGREED.

I do love the 3.55 but if I had 3.31 I’d go to 3.73. If I’m going through the motion of a diff swap might as well get the torsen with the higher ratio.

DUNDEM said:

AGREED.

I do love the 3.55 but if I had 3.31 I’d go to 3.73. If I’m going through the motion of a diff swap might as well get the torsen with the higher ratio.

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Well the 3.55 were really cheap when I got them and I was told it’s only few hours labor to install so I thought the swap wouldn’t be that of a deal. I was under impression 3.73 hurts gas mileage quite a bit and makes first gear unusable?
I love the car so far but it does seem like it could use a hair more low end toque before the turbo kicks in... but I’m comming from a normally aspirated 6 so maybe I just need to take more time to adjust. A more useable top gear would be nice too. Lesser gas mileage not so nice...still undecided!
Where’s our dahm ‘18 fp tune lol

My 17 EB with Perf Pkg came with 3.55 gears. I do a lot of highway driving so I decided to swap for 3.31 gears. It's a little quieter and a little better mileage at highway speeds. And to my surprise my best 0-60 improved by about .2 second. Whatever I lost off the line, I must have more than made up for it at top end.

Blue Moon said:

My 17 EB with Perf Pkg came with 3.55 gears. I do a lot of highway driving so I decided to swap for 3.31 gears. It's a little quieter and a little better mileage at highway speeds. And to my surprise my best 0-60 improved by about .2 second. Whatever I lost off the line, I must have more than made up for it at top end.

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Interesting. Was the swap difficult/expensive? Did you have to buy that install kit?

justme97 said:

Also wondering if the stock differential is "torsen" or if it's not limited slip like the pp, even if I upgrade the gears?

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According to the window sticker for my car it's equipped with a "3.31 ratio limited slip axle." A limited slip differential is standard for all S550 Mustangs. I believe the Torsen option is part of the Performance Pack on the GT, but you'd have to check with Ford to determine if your car is so equipped.

TorqueMan said:

According to the window sticker for my car it's equipped with a "3.31 ratio limited slip axle." A limited slip differential is standard for all S550 Mustangs. I believe the Torsen option is part of the Performance Pack on the GT, but you'd have to check with Ford to determine if your car is so equipped.

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So the standard mustangs don’t have torsen, only the pp mustangs?
Funny the differential is the one muscle car feature that never seems to get much explanation from the manufacturer. In the past I’ve checked the box for torsen LSD just because it looked like a low-cost performance option that would be a pain to install later without even knowing fully what it did. I wish the eb had it as a stand-alone option.