3.15 or 3.55 for my GT Daily Driver? 3.55 Worth the upcharge?

[ListedGuru]

Well to clarify my post is about if you're supercharged then the first few gears on the 3.55 diff are useless meaning shift so quick no traction etc.. so the 3.15 diff tends to do better in those applications. If you option for the 3.55 non-pp version it's also not a torsen differential whereas the 3.55 PP diff is a torsen. I've owned both the 3.15 and 3.55 gears in a Mustang and yes you will notice a difference.

Well dang it your not making this any easier on me, lol. I'm 99% sure I would never supercharge or even mode my non PP GT so I'm guess I'm looking at it from that angle. But you do mention that after having owned the 3.15's and the 3.55's I would notice a difference. I guess what I'm saying is I'll never notice if I don't ever drive a 3.55, lol.

I see that @McSmugger mentioned above that he got the 3.55's non torsen but worries about wearing it out from lots of hard launches. Is there a difference from a wear and tear aspect between the 3.15's and the 3.55's in general. I can see where lots of hard launches especially on a non torsen would be bad but what about just normal daily driving duties. Would you expect that both the 3.15's and 3.55's would last he same amount of time?

Also just an interesting observation that the city mpg's are now rated 16 (up from 15) for the inbound GT's. It appears that bump up is the case for the both 3.15's and the 3.55's w/10A. I had previously thought it might be just the 3.55's getting the city mpg bump but it looks like the 3.15's are too. Not really a big deal just an observation.

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[93-Oct Mayne]

Your comments about still not recommending the EB are interesting. I test drove two EB's and found them to be nice. So nice I initially ordered one, that was until I made the 'mistake' of test driving a GT. My test drive of the GT was really short and at slow speeds and less than optimal weather and road conditions. Just something about even that short drive that made me pony up and want to pay the coyote tax. Maybe it was that intoxicating sound but who knows, lol. Honestly had I not driven a GT I'm sure I would have been perfectly fine with the EB.

I guess that's why I've been asking questions this week about different options as I want to get my GT build just right for me. This week I decided to add active exhaust to my build as it seems like something I will utilize. I figured I would also ask about the 3.55 gears too so here we are. Honestly the more I read and educate myself I'm not sure I would really notice a difference for my use case with the 3.55's compared to the 3.15's. I'm thinking that $1000 upcharge might be better utilized on a warranty to keep my baby safe and protected

It's just really not a Mustang driving experience without the V8. It's tough to describe, but it just feels better. I think you felt it when you described the difference between the two test drives. The Ecoboost is a nice car, but if you're on the forum then you're probably a little more enthusiast than the average person and you'll end up wishing you had the V8

 

[ListedGuru]

Well dang it your not making this any easier on me, lol. I'm 99% sure I would never supercharge or even mode my non PP GT so I'm guess I'm looking at it from that angle. But you do mention that after having owned the 3.15's and the 3.55's I would notice a difference. I guess what I'm saying is I'll never notice if I don't ever drive a 3.55, lol.

I see that @McSmugger mentioned above that he got the 3.55's non torsen but worries about wearing it out from lots of hard launches. Is there a difference from a wear and tear aspect between the 3.15's and the 3.55's in general. I can see where lots of hard launches especially on a non torsen would be bad but what about just normal daily driving duties. Would you expect that both the 3.15's and 3.55's would last he same amount of time?

Also just an interesting observation that the city mpg's are now rated 16 (up from 15) for the inbound GT's. It appears that bump up is the case for the both 3.15's and the 3.55's w/10A. I had previously thought it might be just the 3.55's getting the city mpg bump but it looks like the 3.15's are too. Not really a big deal just an observation.

Just talking to myself here but it just hit me regarding the 16 mpg city rating on the inbound cars I'm seeing. All have the auto stop start system so I bet this is the difference. The 10A cars without auto stop start should be rated at 15 city whereas if it has auto stop start it should be 16 city. But I guess if you get a GT w/ auto stop start and you turn off that feature your city rating is back to 15 LOL. Honestly I really won't want auto stop start on my car but it sure looks like it will have unless I can find one on a lot but that's tough to do around me with my specs.

 

[JediMindTrix]

Well dang it your not making this any easier on me, lol. I'm 99% sure I would never supercharge or even mode my non PP GT so I'm guess I'm looking at it from that angle. But you do mention that after having owned the 3.15's and the 3.55's I would notice a difference. I guess what I'm saying is I'll never notice if I don't ever drive a 3.55, lol.

I see that @McSmugger mentioned above that he got the 3.55's non torsen but worries about wearing it out from lots of hard launches. Is there a difference from a wear and tear aspect between the 3.15's and the 3.55's in general. I can see where lots of hard launches especially on a non torsen would be bad but what about just normal daily driving duties. Would you expect that both the 3.15's and 3.55's would last he same amount of time?

Also just an interesting observation that the city mpg's are now rated 16 (up from 15) for the inbound GT's. It appears that bump up is the case for the both 3.15's and the 3.55's w/10A. I had previously thought it might be just the 3.55's getting the city mpg bump but it looks like the 3.15's are too. Not really a big deal just an observation.

3.55 will definitely have harder launches than the 3.15 gears but I would not anticipate it to last significantly less longer due to that fact. Every unique buildable combination is thoroughly tested during R&D for durability to meet certain internal and external standards even these kinds of user test cases such as McSmugger pointed out. If you are just daily driving your mustang and doing the spirited driving kind of launches, then you will have no issues with wear and tear or longevity. You will definitely get better MPG's with the 3.15 gears rather than the 3.55 gears but at that point you're splitting hairs. This is a performance coupe so my opinion would be to opt for the packages that enhance the experience without breaking the bank. GT base 301A, 3.55 gears, active valve exhaust and the brembo package equals the best bang for you buck in a daily driver.

 

[HWill]

I have driven both 3.15 and 3.55. You will notice a difference.

I got 3.55 with my auto cause I plan to go FI. I would have went 3.73 if they offered it like I had in my Whipple F150. I never had traction issues with the higher gears.
IMO the least I would run in a FI 10spd Auto is 3.55

 

[ListedGuru]

I have driven both 3.15 and 3.55. You will notice a difference.

I got 3.55 with my auto cause I plan to go FI. I would have went 3.73 if they offered it like I had in my Whipple F150. I never had traction issues with the higher gears.
IMO the least I would run in a FI 10spd Auto is 3.55

So I will still notice a difference even if I don't plan on supercharging or really doing any mods at all?

Any idea what the rpm's are at 70 or 75 mph with the 3.55's? I know they will be higher than with the 3.15's but I wonder how much higher? The mpg's on the sticker for both cars are identical so I would think the mpg difference the two would be very small (if any)?

 

[ListedGuru]

3.55 will definitely have harder launches than the 3.15 gears but I would not anticipate it to last significantly less longer due to that fact. Every unique buildable combination is thoroughly tested during R&D for durability to meet certain internal and external standards even these kinds of user test cases such as McSmugger pointed out. If you are just daily driving your mustang and doing the spirited driving kind of launches, then you will have no issues with wear and tear or longevity. You will definitely get better MPG's with the 3.15 gears rather than the 3.55 gears but at that point you're splitting hairs. This is a performance coupe so my opinion would be to opt for the packages that enhance the experience without breaking the bank. GT base 301A, 3.55 gears, active valve exhaust and the brembo package equals the best bang for you buck in a daily driver.

So when you say the 3.55's will have harder launches does that mean only when your really ripping on it? If I'm just taking of normally from a stop will the 3.55's feel the same (nice and smooth) as the 3.15's? I mean I shouldn't notice any jerkiness or anything similar when driving normally with the 3.55's just faster smooth acceleration correct?

You also mention I'll see better mpg's with the 3.15's compared to the 3.55's but honestly it shouldn't be much different at all would it? I mean the GT's with both gears are rated the same for city and highway mpg's.

As far as your take on the best bang for the buck for a daily driver I guess I'm 50% there thus car. I have the 301A pkg and just recently added active exhaust to my build. I'm still debating on the 3.55's - thus all the questions. As far as the brembo's are you talking about upgrading to the 19" brembo system w/performance linings or as I understand it the GT's already come with brembos in the front correct?

Sorry for all the questions just trying to educate myself so I can make the best decision on this GT as I would like to keep it 10+ years

 

[HWill]

So I will still notice a difference even if I don't plan on supercharging or really doing any mods at all?

Any idea what the rpm's are at 70 or 75 mph with the 3.55's? I know they will be higher than with the 3.15's but I wonder how much higher? The mpg's on the sticker for both cars are identical so I would think the mpg difference the two would be very small (if any)?

IMO you are better off going 3.55 if you want to stay NA or FI. But I would definitely recommend them if you are keeping the car stock.

And yes harder launches does mean when you are flooring it. Regular driving the car will just feel like it accelerates better than the 3.15

MPG is a moot point even on paper.

 

[horned-toad]

Yes I'm getting the 10A here in the US. I think the 10A is a $1595 upcharge here and the 3.55's are a $955 or so upcharge here (can't remember exact amount). Honestly I wouldn't mind the manual myself but someone in the household can't drive a stick and really where we live the traffic sucks so there's that too.

3.55 and don't look back. But better would be to teach everyone how to drive stick. There's something wrong with you to sit in traffic day in day out regardless of the trans.

 

[9secondko]

in my experience, there is a notable difference both in actual numbers as well as by the seat of your pants going to 3.55 and again going to 4.11 (4.09 in this case).

get the 3.55s. You’ll be really glad.

3.15s is grandma mode.

 

[dusman59]

I have had 3:55's in all 3 of my Mustangs and find it perfect with the Brogwarner t4, mt82, and a10. I find it the best overall ratio for normal spirited street driving. Going SC it would be too tall. I can't speak with the Tremec ratios as they have many depending on MY Mustang and model(Shelby,Mach1).

 

[JAM486HP]

Let's all be honest here. No one buys a Mustang GT for fuel economy

I'm averaging 13mpg, that's good for the economy of nearest gas station

 

[JAM486HP]

But really how much of a difference does it make? You mention the 3.55's do make a difference in gears 1-2 on the 10A but is it something I would really ever miss? Especially if I don't drive one with the 3.55's.

I've seen posts online that say that the difference (in actual times, etc) isn't even noticeable. Maybe I would notice in the seat of the pants meter but I'm not sure if it's worth the coin for my use case. Like I mentioned in another post that almost $1K might be better spent on an extended warranty

Not trying to doubt you or anyone that the 3.55's do make a difference but I guess I'm just wondering if it's something I would even notice. I guess if I don't test drive a 3..55 I'll never know what I'm missing anyway, lol.

If you have the money go 3.55, you can always lay off the throttle if you don't want a hard launch.

I have 3.15 and I can see why some describe it as sluggish, especially if you had 3.55's. I'm coming from an '88 GT so the '24 GT with 3.15's is a beast.

 

[ListedGuru]

If you have the money go 3.55, you can always lay off the throttle if you don't want a hard launch.

I have 3.15 and I can see why some describe it as sluggish, especially if you had 3.55's. I'm coming from an '88 GT so the '24 GT with 3.15's is a beast.

Curious if you have any experience with 3.55's? Did you test drive a 3.55 24 GT before deciding on your 3.15? Honestly I'm still on the fence about what to do. I think I need to track down a 24 with 3.55's and compare it to one with 3.15's.

 

[9secondko]

Curious if you have any experience with 3.55's? Did you test drive a 3.55 24 GT before deciding on your 3.15? Honestly I'm still on the fence about what to do. I think I need to track down a 24 with 3.55's and compare it to one with 3.15's.

thays peobsbly the only way to sell you on it.
Go to your dealer. Test drive a 3.15 and then a 3.55 and be sure to get on the throttle. My bet is you’ll never give the 3.15s a thought again.

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