MRGTX

Hey, guys...
I just ordered up my Sterling Grey 2011 GT and I'm extremely excited to pick it up...in about 8 weeks.

So...I'm trading in my 2009 GT which was equipt with the 3.31 gears...which was my only regret on an otherwise excellent car. The gears really held back the performance compared to my friend's 3.73 equipt machine...So this time I went with the 3.73s figuring that the higher redline and the 6spd would negate any ill effects that the 4.6L/5spd car would have suffered. Plus, all of the car mags are testing with the 3.73s so I figured that this was probably the hot set up.

After reading a lot of threads on this forum, I'm starting to question my decision...and it seems that these might not be the best gears...and even a 3.31 car has been seen turning mid 12s?

My car will be daily driven with plenty of highway...my goal is to have the quickest possible ride that will be at least as livable as my 2009 GT was.

What do you think- Did I screw up? It's probably not too late to change the order. Thanks for any opinions or advice!!

Mustang05

Hell No. I think 3.73s are the best street/strip gears

MRGTX

Glad to hear it...thanks for the input.

So you think it's still a good choice for a car that will live half its life on the freeway?

2K3 Mach

I too had an 07 with 3.31s. Yanked them out for 3.73s and never looked back. Fuel economy loss is minimal.

And I'm not buying the argument that the 3.73s will be slower cause of the shift points. That's a good problem to have. It's like saying "Your girlfriend is too hot"...

825LTRGT

From the trans gear ratios, it looks like 3.73s in the '11s are close to 4.10s in the '05-'10s.

3.55s are close to 3.73s

and 3.31s are close to 3.55s

It looks like 1st gear in the '11s with .73s is pretty steep. But it depends on what you like.

Tony Alonso

Does "livable" mean "not turning higher RPMs" at freeway speeds?
Is acceleration around town (0-60mph) more important than that at freeway speeds (60mph+)?
Is fuel economy more important than acceleration?

These are the questions I would be asking myself to see if I selected the optimal gear for my application.

m4reapr

in 6th gear there is about a 150rpm difference in each rear ratio
or
in 6th gear 2k rpm equals 76mph, 70 mph, 66 mph for 3.31, 3.55, 3.73

i always benchmark 2k rpm on the highway because V8s have usually been low revvers, 5500-6200 redlines

this is a dohc motor, 7k redline, it will want to live or feel right at home in a little higher rpm range
that being said, it has huge hp and tq so it could run around with a 2.73

can't go wrong with any ratio
don't hear or read anybody who got the 3.73 complaining about it being too short or 3.31 too tall, does that mean 3.55 is just right
i ordered it with 3.73
the threads you are reading are on the fine edge of deciphering what if...?

the internet is great but with all the info and opinions i think everybody becomes an information hypochondriac

joe91898

We just bought a 2010 GT auto trans with 373s (installed by previous owner). I would rather have 355s like my 03 Mach1. Our car spends most of the time on the highway. To me it revs to high at 75mph, plus I don't plan on racing it on or off the road. I know if I were to buy an 11 it would have the 331's just because of the type of driving I would be doing. I may change my 10 355s

MRGTX

Well put.


Well... this is interesting...and I appreciate the specifics
There was always a crowd who insisted that 4.10s are just fine in a daily driver... but is this the same crowd that favors the 3.73s here?

Any guesses on the impact/ long term longevity of the motor?

Thanks again to everybody for the insight and opinions. This forum is superb.

krnpimpsta

I'd say go with 3.73 for maximum accelleration.

In some cases, you may get better drag strip quarter mile time with the 3.31, but that's only an artifact of the quarter mile run - it's because the 3.73 may have to shift one additional time before the quarter mile is over.

In the real world, you just mash the pedal down and keep going, even after you've gone 1/4 of a mile... so it doesn't matter if you have to shift 1 second earlier or 1 second later. If you want maximum performance in the real world, go with the 3.73.

coffeejolts

Your worry is misplaced. The 3.73s will be great. I have attached a spreadsheet that details the RPMs in each gear for 3.73, 3.55, and 3.31 ratios. The difference at 70mph in 6th is about 200 RPM. You won't even notice it on the highway, and the increase in bottom end acceleration will be way worth it. The only reason I can see to get 3.31 or 3.55 gears is if you want to avoid a possible shift to 5th in the 1/4 mile.

Tony Alonso

Given the Ford durability tests for powertrains, gear selection should not have an impact.


If you decide to add forced induction to the engine, then I would start to worry about engine longevity. That, of course, is an entirely different topic with many more considerations.

SuperSugeKnight

3.31 - Highway/Max MPG gears.

3.55 - Good all around gear.

3.73 - Max performance streetable gears, Good street/drag racing gears.

dmhines

IF you were in Georgia ... I'd swap my 3.55 rear axle for your 3.73 rear axle.

Automagically

I will make my decision when I drive the 2011 with the different gears, only then can I tell. Still leaning towards the 3.31, I need the highway mileage. 3.55 might work if only I feel it's more fun.

MRGTX

Spectacular.... this pretty much alleviates all worry. Thanks!!

Who would have guessed that math would be useful for something??!

Gene K

Compared to your car:

In 1st the axle will act one axle ratio lower than it is.
In 6th the axle will act one axle ratio taller than it is.
In the traps 4th will act exactly like 3rd did except you will be turning 10% more rpm because you are going 10% faster.
The gear ratios are way closer in the new trans and the engine is so torquey and smooth that at times you have to look at the tach or floor the throttle to tell which of 3 different gears you are in.

I said months ago that I felt all the gears would be within 1/10 Showroom Stock.
So far Ive seen nothing to change my opinion. Buy what you like.

Best 3.31 Pass - Mike at Powerhouse in a 400A / M6 / 3.31 / 18" AS - 12.77 @ 112
Best 3.73 Pass - Evan at MM&FF in a 402A / M6 / 3.73 / 19" AS - 12.69 @ 112.61 (On a 2.06 60' which is unusually lackluster for him - Crappy track prep most likely).

Evans 60' tells me these cars have a 12.4 in them sooner rather than later (1.8's are doable in Showroom Stock 2005+ Cars.)

JMHO That and a buck will buy you a cup of cheap coffee...

AWESOMO 4000

These cars aren't even broken in yet - there is a lot of potential left to be had. Most of them have under 1,000 miles. I know my 07 GT felt like a total DOG compared to my 04 GTO at that time. When I finally ran it with 10k on it, it ran .10 faster than my GTO did at the same point in its life.

cdynaco

True except that with 3.73's and the new 6 spd, 1st redlines too fast. And too much 1st gear torque simply spins tires. Either problem wastes portions of seconds - and that matters in the 1/4. Can you start in 2nd?

I'd go 3.55's with the 6 pd.

Gene K

Hmmmm.... I think I already did. Unfortunately we have to pay for the privilege. The Canadians get them standard.