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

[DuRsT]

I pulled up the Ford Racing page yesterday but couldn't find the pre-built rears you guys are talking about. Anyone have a link?

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[Bluemustang]

Buy a used 3.55 Torsen diff housing out of a 2018 or 2019. It's what I did. The 3.55, 3.73, 3.31s won't fit in the housing used for the 3.15s I believe.

But if you swap out the entire housing, you can get a better differential and shorter gears. The auto pinion flanges must be the same for all 15-19 cars since I used a complete 2018 PP housing to swap into my 2015 car.

 

[Jetnoise]

https://www.steeda.com/ford-racing-...tial-housing-3.55-15-16-all-m-4001-88355.html

 

[Burkey]

3.15 to a 3.55 might not sound like a % jump ....
But it is
You'll definitely notice the difference

13% is fairly substantial. Hell, we all rave about the difference from 93 to E85 which is roughly 10%

 

[Balr14]

I am going to ask my local dealer if they can do it and the cost. I'm guessing $2k total... I think it's worth it.

 

[Sparko]

It’s very feasible. I did it at the dealer on my 2013 gt 500 vert...from 3.31 to 3.73. Made a huge difference. All parts and expert labor ( with warranty) cost about $ 1200

 

[Intrepid175]

I swapped the rear diff on my 2016 GT convertible w/ MT. I bought the car used and it came with the optional 3.55's which was the one option I really didn't want so I found a complete differential off of Ebay for $430 with the standard 3.31 gears and took a chance. A mechanic friend of mine got permission to use the shop he worked at on an off day and it took us a little over two hours to swap the differential assemblies. We removed the exhaust and the braces first and the rest of it went very easily. My reason for making the change was, first, I really didn't care about the performance difference. That's not really why I bought the car. I found the lower gearing combined with the close ratios of the first four gears on the MT to be a bit fussy. Lots of shifting and not a lot of going down the road in normal driving around which gets old in a hurry for me. When you're hard on it, it really scoots but that's not practical most of the time. Besides, I bought this car with the intent of taking as many road trips as I can and I prefer the more relaxed cruising rpms with the higher final drive. It only works out to about 200 rpm at 70 in 6th gear which doesn't sound like much but it does make a difference. It also added almost 10 mph on the top end for each gear. I've only tested that through 4th. Anyway, I like the difference in how the car feels and I don't have to row gears as much in normal traffic which is something I like.

One other thing you'll need to do is have the ECU refreshed to reflect the change in gear ratios or else you're speedometer won't be accurate. I found that my car wouldn't accept large throttle applications until I got that done. I could nurse it up to about 60 mph if I did it "very" easily but stomping down on it returned nothing. It was like the throttle wasn't even connected. I've still got my original 3.55 differential assembly if anyone might be interested. It's got about 17k miles on it and I'll make you a good deal but we need to talk about that directly.

 

[Brazos609]

There is a brand new FRPP 3.73 loaded Torsen differential assembly for sale here. You can install it yourself with just wrenches.

https://www.mustang6g.com/forums/threads/ford-racing-torsen-diff.127698/

 

[Daryl333]

I swapped the rear diff on my 2016 GT convertible w/ MT. I bought the car used and it came with the optional 3.55's which was the one option I really didn't want so I found a complete differential off of Ebay for $430 with the standard 3.31 gears and took a chance. A mechanic friend of mine got permission to use the shop he worked at on an off day and it took us a little over two hours to swap the differential assemblies. We removed the exhaust and the braces first and the rest of it went very easily. My reason for making the change was, first, I really didn't care about the performance difference. That's not really why I bought the car. I found the lower gearing combined with the close ratios of the first four gears on the MT to be a bit fussy. Lots of shifting and not a lot of going down the road in normal driving around which gets old in a hurry for me. When you're hard on it, it really scoots but that's not practical most of the time. Besides, I bought this car with the intent of taking as many road trips as I can and I prefer the more relaxed cruising rpms with the higher final drive. It only works out to about 200 rpm at 70 in 6th gear which doesn't sound like much but it does make a difference. It also added almost 10 mph on the top end for each gear. I've only tested that through 4th. Anyway, I like the difference in how the car feels and I don't have to row gears as much in normal traffic which is something I like.

One other thing you'll need to do is have the ECU refreshed to reflect the change in gear ratios or else you're speedometer won't be accurate. I found that my car wouldn't accept large throttle applications until I got that done. I could nurse it up to about 60 mph if I did it "very" easily but stomping down on it returned nothing. It was like the throttle wasn't even connected. I've still got my original 3.55 differential assembly if anyone might be interested. It's got about 17k miles on it and I'll make you a good deal but we need to talk about that directly.

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