A10 3:15 vs 3:55

Grintch said:

So it has you in 10th gear at 40 mph? That's terrible, does putting it in Sport mode make it not rush to shift up as much?

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To clarify - it will stay in 10th down to 42 mph before it downshifts to 9th. Yes, Sport is much better.

I wish i had the 355. With my good sticky tires it bites and barely spins,and is gone and could certainly handle a bit more snap in first gear to make it more fun. Once moving I find the choice meaningless with the 10 gears as it finds a happy gear anyway. I'd still have got the 355 if i could have found one.

Rash said:

To clarify - it will stay in 10th down to 42 mph before it downshifts to 9th. Yes, Sport is much better.

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Thats a hypermile capability: the ability to stay in 10th at low rpm and lug at light load on 87 with Direct Injection is actually quite an engineering feat.
Many people want to control the downshift themselves by either paddling for a single downshift, or adding a hair of throttle position to trigger the downshift.
Or.. limit acceleration...
Or use sport mode but then you lose that capability.

GM/Chevy programming going back before 2014 has additional hidden shift strategies. Maybe check and see if Ford has them also?
Try this:
After you get above 40 in D, shift to S for at least 10 seconds, then back to D. In the Chevy firmware, this triggers a modified D mode that is somewhere between D(eco) and S or “trailer” mode. Shift to neutral and then back to D to clear it.

With Direct Injection and light loads, you can operate like a diesel for hypermiling and see what kind of mileage you get. Not sure from your posts if you are asking if its ok? Dude, rock that hyper mileage!

Enjoy your DI technology. Ford engineers certainly set the upshift before any damaging loads on rings lands or bearings.

If you want to accelerate, press the gas hard enough to grab the next gear down. If you want to hypermile, just keep babying it like you are.

I *hear* there is more than one engineer at Ford that has been known to be *that* driver that leaves 20 car lengths ahead coming into a red light to allow light acceleration to keep pace w traffic. Lol. 30+ mpg on a V8?
Hypermile your Mustang!

Make sure to factor in any wheel/tire change as well. On my 16', I went with a 3.15 and when combo'd with my 305/35/20's (28.5" tall rears), the gears were loooooong.

I was not going to make the same mistake again and went with the 3.55's. Regarding mileage, I had the cruise set on 78mph and was getting high 23's mpg with only 200 miles on the car. Even if there were a few mpg's salvaged, the fun factor of the 3.55's is worth it.

So to revive this thread a bit.

A dealer I am working with has a convertible coming in with all the specs I want (Royal Crimson, Auto, AE, Black Accent, Safe and Secure, 400a, Ceramic).

However it has the 3.15 rear end and I really think I want the 3.55.

It will be simply a comfy cruiser and daily so I am not sure it would be worth letting this go and waiting on most likely a 2019 in the right rear end.

I do plan at some point getting at least a 93/Flex tune...so that in itself might make the point moot.

Only positives on waiting would be:

2019 model year (hopefully fixed any lingering issues with 2018s)
400a package would then include heated steering wheel and memory seats I believe (used to take safe and secure and 401a for these)

Negatives:

No Royal Crimson, waiting longer, possible worse incentives.

Thoughts?

is there any video showing two cars running with the different gear ratio? back 10 years ago this gear ratio difference would be a big deal.

greengoblin31 said:

is there any video showing two cars running with the different gear ratio? back 10 years ago this gear ratio difference would be a big deal.

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Was at the track with my 3.15 , friend had the 3.55 PP both autos all other options the same except my car was non pp, they both had and used drag mode I was never behind by more then 0.15ish. so if that is a big deal is for you to decide, lol.

kidamer said:

Was at the track with my 3.15 , friend had the 3.55 PP both autos all other options the same except my car was non pp, they both had and used drag mode I was never behind by more then 0.15ish. so if that is a big deal is for you to decide, lol.

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So essentially the difference is a car and a half through the 1/4. Can you remember your 60' and 1/8th compared to his?

*Edit* Is this with the '17 you have in your sig. or a '18 with the 10 speed?

MX Raptor said:

So essentially the difference is a car and a half through the 1/4. Can you remember your 60' and 1/8th compared to his?

*Edit* Is this with the '17 you have in your sig. or a '18 with the 10 speed?

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sorry yes its an 18 now with the 10 speed, yes the head to heads we did I usually was at his rear qtr panel. From memory the 60fts where he did get out faster then me his were 1.85's mine were 1.92's. I dont recall the 1/8th sadly. he just ever so slightly, pulled from me until the roughly the 1/8 mi then I would say both cars were equal we both finished at the same distance at the end of the 1/4 mi as we were at the 1/8. take that as you will

sigintel said:

I *hear* there is more than one engineer at Ford that has been known to be *that* driver that leaves 20 car lengths ahead coming into a red light to allow light acceleration to keep pace w traffic. Lol. 30+ mpg on a V8?
Hypermile your Mustang!

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LOL, that's what engineers do. It's also fun to blow by the car that was in a hurry to get to a stop.

greengoblin31 said:

is there any video showing two cars running with the different gear ratio? back 10 years ago this gear ratio difference would be a big deal.

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Agreed, 10 years ago there would be a decent difference between the 3.15 and 3.55's. Remember when the difference in the 80's was a 3.08 vs the 2.73? With the 2.73's you were practically done with the 1/4 when you were shifting into 3rd!

The A10 keeps the engine in the powerband so the impact isn't as great as it used to be except for lower RPM ranges during takeoff etc..

Dory said:

As a follow up question, if you don’t get PP1 or PP2, but custom order the 3:55, is it the same 3:55 you would get with either PP? It is confusing to me. Do all Mustangs have a positraction or just the PPs?

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If you get a PP car you get a Torsen rear and with a non PP car you get the regular limited slip traction lock type rear.

I have a 2016 base GT w/3.55:1 and specifically hunted 1 down. But yes, 10 years ago it would have big implications. I enjoy "barking" 2nd gear sometimes without trying and my mileage is still 20-23 on these Texas highways.

I'm not much on the technical jargon. I have had both 315 & 355 geared Mustangs Supercharged & naturally aspirated.The 315 gears got better gas mileage. They were all automatics. S197 & S550 generations.355 seems much quicker for power on regular highway driving. My 2018 GT Premium A10 PP1 has 355 gears. Its still all about preference & usage.:shrug:

3.15's will pay dividends when you start making big boy power. the 8.99 pass was on 3.15's and beefcakes 9.2-9.3 used 3.15's.