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Is it feasible to change rear-end gears in 2018 GT Premium convertible?

Balr14

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The 3.15 gears seem a little too tall for the engine. 3.55 seems like a better choice, especially for a convertible. Is swapping gears a big deal? I was also thinking of wider rims and tires. I assume wider 18" wheels and tires would fit OK?
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Gear ratio swapping is relatively straightforward. Might as well be sure to get the upgraded limited slip while you're in there.

Plenty of tire-wheel size-application discussion can be found by a thoughtful search of the forum.
 

3star2nr

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Its not worth the effort imho... Its not going to give you a dramatic increase in acceleration for how much ur paying...
I suggest you just try to make more power.

The rear end should be one of the last mods you do...that said if u really want to do it, id research just swapping the entire diiff verses messing around swapping out gears. You can find these cars at junk yards now and with a little patience you can pick up any ratio you want...

I'm not sure if there are any case differences between verts and coupes but that should be something a service advisor may be able to answer.

Also hang on to your 3.15 once u start adding power u may want to go back to it
 
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TheReaper

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The 3.15 gears seem a little too tall for the engine. 3.55 seems like a better choice, especially for a convertible. Is swapping gears a big deal? I was also thinking of wider rims and tires. I assume wider 18" wheels and tires would fit OK?
Do it, you will love the 355 with the 10r80.
 

I Bleed Ford Blue

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I'm not sure if there are any case differences between verts and coupes but that should be something a service advisor may be able to answer.

Also hang on to your 3.15 once u start adding power u may want to go back to it
Ford racing sells preloaded center sections with trac-loc or torsen diffs and nowhere in the catalog do they mention it only fits coupes. I know it's not a definitive answer, but it's something to consider.
 

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3star2nr

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Ford racing sells preloaded center sections with trac-loc or torsen diffs and nowhere in the catalog do they mention it only fits coupes. I know it's not a definitive answer, but it's something to consider.
I agree i don't see any reason for them to be different but convertibles sometimes have extra reinforcements done to the frame to accommodate the missing roof so i was suggesting to ask just so there's no issues on install
 

I Bleed Ford Blue

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I have a vert and the brace actually runs under the car from where the b pillar would normally be to behind the rear suspension cradle and its bolted to the car and the rear cradle.
 

Sigster

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I also am curious about the 3.55 upgrade from 3.15 with the 10A. I know the PP cars come with that ratio in automatic. But the percentage of difference between those 2 numbers is not a lot. It also appears that you have to change your entire differential to accommodate any gear swap, so now you are talking significant money. And as someone pointed out in another thread, your 10A has TEN gears already! So I'm very curious to hear from anyone that has actual done this swap - especially on a heavier convertible - and see what the results if any were felt in low/mid range grunt. Unless someone has had great results, I'm personally holding out for the long awaited Ford Performance power pack 2, if they'd ever get off their duffs and release that for MY 18/19...
 

Jetnoise

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the percentage of difference between those 2 numbers is not a lot.
3.15 to a 3.55 might not sound like a % jump ....
But it is
You'll definitely notice the difference
 

DuRsT

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Ford racing sells preloaded center sections with trac-loc or torsen diffs and nowhere in the catalog do they mention it only fits coupes. I know it's not a definitive answer, but it's something to consider.
Did not know this, appreciated.
 

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MaskedRacerX

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I also am curious about the 3.55 upgrade from 3.15 with the 10A. I know the PP cars come with that ratio in automatic.
PP cars have the 3.55 with a TORSEN lSD, but there's also a standalone 3.55 for non-Perf Pack cars (it's cheap too, like $795). The 3.55 was one of my must have options, either via a PP or the option, it makes a big difference, even with 10 gears :)
 

MaskedRacerX

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Oh, and you certainly don't have to stick with 18", you can go 19" (see the Perk Pack setup), or 20", and in any of those, go much wider.

I'm running a 20x10 front with a 285/35 tire, and a 20x11 rear with a 305/35 tire :D
 
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Balr14

Balr14

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Oh, and you certainly don't have to stick with 18", you can go 19" (see the Perk Pack setup), or 20", and in any of those, go much wider.

I'm running a 20x10 front with a 285/35 tire, and a 20x11 rear with a 305/35 tire :D
Road conditions around here are very hard on 19" and 20" wheels. The more sidewall I have the better. I'd used to opt for 16" wheels on past cars I've owned, when everyone else was going 17" and 18".

Does that standalone 3.55 require other changes?
 

MaskedRacerX

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Road conditions around here are very hard on 19" and 20" wheels. The more sidewall I have the better. I'd used to opt for 16" wheels on past cars I've owned, when everyone else was going 17" and 18".

Does that standalone 3.55 require other changes?

Ahh, I hear you (and see your location now), still, you can get sporty sized setups and use tires with slightly taller sidewalls. Like for my setup, some people go with a 30 series tire, I went with a 35, it looks great, fills the fenders a little more, and slightly improves the ride while offering a little better wheel protection.

When I said "standalone" above, I mean, it was a factory option that wasn't bundled into another package. Like someone said, you can get complete rear ends ready to bolt up - I'm not sure if you'd need to flash the ECU with the gear change[?] I'm sure it's easily done at a dealer, or a shop with a programming tool.
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