MRGTX

Do you regret opting for the 3.55s?

Like most 3.55 gear folks, I picked them based on very rational grounds such as wanting a more useful 1st and 2nd (especially for autocross), slightly better MPG, avoiding a 4-5 shift in the quarter mile (with any power improvements), etc.

I can't help but think that the way I'm actually driving this car, I would have done better with the 3.73s...but I have only driven 5.0s with 3.31 and 3.55s so far...so I don't know for sure. I suppose they can be changed later...The difference between the 3.31s and the 3.55s is fairly substantial (though both are plenty quick, really).

What do you think? Have you driven both? Is there a big difference?

Modshack

If I had the choice I'd have gone with the 3.55's. 3.73 now.

cdynaco

I agree with your reasoning for choosing the 3.55's with the new 6spd.

However, it sounds like you need to rev that sucker!! Let it breathe and I bet those 3.55's will talk to you!

danimal15

I'm pretty happy with 3.55 and am glad I didn't pick 3.73. Even with 3.55, the 1st two gears aren't that useful. Since I stop at lots of red lights on my commute, I can't imagine having the higher gears, which would mean even more shifting.

Anyone who's tried the 3.31 - is there a noticeable difference at low gear compared to the 3.55 and 3.73?

falhulk

Not sure what you guys are talking about.....even with 3.73's 1st is perfectly usable. 2nd goes all the way to 60 so thats crazy to say the first 2 gears are not usable. I would think that in autocross it would be better to have the car in 2nd the whole time. The 3.73's would be better.

3Mach1

I have not driven a new Gt but here are my thoughts. If I could afford one I would chose the 3.55 and here is why. When I bought my Mach 1 I thought that the 3.55 gears in it would be too high. Nothing could be further from the truth. They are almost perfect for me. For those of you who dont know the Machs had a .62 fifth gear. Comparing it to the new GT's rpm wise I would get lower gears 1 through 4 with 5th being the same as my 4th. The 6th gear on the GT would actually lower my rpm by 100 at 70mph.

Its the best of both worlds and with another 100 hp on tap whats not to like. The Mach 1's are like a six speed with no fifth. That last gear is really high. But, for my type of driving it works well. I doubt at the end of the day there is much difference performance wise or Fuel economy wise. Im sure there is a bit but isnt a 3.31 car still the fastest one documented stock down the quarter? Im just glad Ford gave the option but when you think about it they are making pure profit because it costs the same to put in a 3.31 as it does a 3.73 or 3.55.

cdynaco

A Champion Autocrosser would disagree with you...

falhulk

Well, I dont autocross so I will digress....but at the same time he states "road course". When I think autocrossing I think big parking lot and cones. Others who race road courses have said that the 3.73's are perfect for them. The 1/4 argument holds water but everything else I doubt.

kn7671

I don't really think you should stress over this too much. Unless you are just trying to gain every last little bit of acceleration, then it only makes a marginal difference in acceleration along with a slight drop in economy, and slight increase in rev's.

Here are some quick numbers:

3.31's @ 65mph in 6th = 1725 rpms
3.55's @ 65mph in 6th = 1850 rpms
3.73's @ 65mph in 6th = 1950 rpms

Top speed in 4th gear @6800 rpms:
3.31's = 126mph
3.55's = 117mph
3.73's = 112mph

Liquid

I haven't pulled the trigger yet, but this is the hardest decision I'm facing.

falhulk

It's not the 4th-6th gears that it makes a diffrence in. At the same time, like I said at first, the change from 3.55 to 3.73 does not all of a sudden make 1st and second "unuseable". 2nd is the best gear in the car!

kn7671

Well even based on that, the differences are not that great. Here are gears 1-5 @ 6800rpms with stock diameter tires. And I don't know about you, but a 5mph difference @ 6800 rpms in 1st gear, and a 7mph difference in 2nd gear between 3.31 and 3.73 gears does not make 1st or 2nd unusable.

Top speed in 1st gear @6800 rpms:
3.31's = 45mph
3.55's = 42mph
3.73's = 40mph

Top speed in 2nd gear @6800 rpms:
3.31's = 68mph
3.55's = 64mph
3.73's = 61mph

Top speed in 3rd gear @6800 rpms:
3.31's = 98mph
3.55's = 92mph
3.73's = 87mph

Top speed in 4th gear @6800 rpms:
3.31's = 126mph
3.55's = 117mph
3.73's = 112mph

Top speed in 5th gear @6800 rpms:
3.31's = 166mph
3.55's = 155mph
3.73's = 148mph

cdynaco

In case you didn't open the thread he was responding to road course questions. But yes, his autocrossing is cones etc. and I think there was another post about why he felt 3.31's were best for parking lot courses.

cdynaco

Where I'm coming from is comparing the 3.73's with the 5spd Tremec. For the 5spd, 4.10's were too much (1st is pretty useless as it raps too fast and in the 1/4 you have to make an extra shift to 4th. Seconds ticking away each shift.).

So my thoughts have been the 3.73 with the 6spd would be similar to the 4.10/5spd setup.

By your chart the 3.55's came closest to my 3.73/5spd for 1st & 2nd. 1st redlines (6500) at 45, 2nd at 65, but 3rd tops out at 105 and finishes the 1/4 without an extra shift.

As to 2 lane mountain twisties, 2nd and 3rd is where I live.

Killa-B

I ordered mine with 3.73s and while I dont regret it, if I were to order this car again, I would go 3.55. The reason is that I want the Roush supercharger and I think it would work better with the 3.55s. When ordering the car I didnt even consider the idea of a supercharger. As the car is now, I am completely happy with the 3.73s, I like shifting gears........

SD CALSPCL

I don't have any regrets. I think it is a nice blend of performance and economy. Most of my driving is on the Interstate, and this ratio seems just right.

AWESOMO 4000

Another thing to remember too, if you are going to get a tune - which pretty much everybody here will end up doing - is you're going to be making a little more power to go faster through 4th (i.e., through traps for drag racing at the strip), but you're also raising the rev limiter another 300-500rpm. Also, remember, 4th gear in a 6-speed isn't really the "4th gear"/1:1 ratio we're used to...it's 3rd gear in the previous model(s).

kn7671

Or you can say, 5th is the new 4th.

Driver72

I did all my calculations and consideration BEFORE i ordered my 5.0
and it was (along with other racers) a no brainer to get the 3.55's

I concluded it's the best ratio for this car.

BTW, redline in 4th on the 3.55's is 119 mph according to my speedo and GPS.
Add intake, exhaust, tune and even the 525 hp supercharger to the car, with a slight increase in redline and you should still be able to hold 4th gear in the 1/4 with the 3.55's too.

It's the reason Ford uses that ratio on the GT500 (and even with the SVT PP they only give it the 3.73's because the rear tires are taller than the non SVT PP GT500 so they needed to give the SVT PP version 3.73's to equal the 3.55 ratio of the non SVT PP car).

3.31's would probably be the best choice for anybody considering the 624 hp supercharged version or for as Sam has stated autocrossing.

3.55's seem best to me for stock performance levels and especially for power increases of up to 100-120 hp over stock if at a drag strip or track where with a 250 rpm redline increase you'll be able to do around 124 mph in 4th.

So don't regret getting the 3.55's for a second, you made the right choice to begin with.
You can shift to 5th at 40 mph and still have plenty of acceleration.
And even with the 3.55's this car seems to need a pretty decent amount of shifting, the 3.73's in town (at least a town with traffic and a decent amount of traffic lights) would mean shifting way too much to even be considered fun in my book.
3.55's rock, worry not.

falhulk

Again,absolutely untrue. Under normal conditions there is no more shifting with 3.73's then 3.55's. You still shift at the same speeds!