bruins004

So I have been pondering if I should change my order and get the 3.31 gears for the V6 Mustang.
Will it accelerate that much faster?
Cant these gears be added afterwards?

Also, I already put an order in.
If it hasnt been pulled yet can I add this option?
And if so would my order go to the back of the list again?

Thanks

Boomer

I'd get the gears, but that's just me.

eci

If you plan on driving 100 miles per day commuting on the Interstate you want the 2.73's. Otherwise, no.

future9er24

You'll enjoy the 3.73s for sure. if its too much of a hassle to change your order, you can always get it done aftermarket

jeff s

Yes, the gears can be added after.

Yes, if your order hasn't been pulled you can still make the change.

No, you won't go to the back of the line, if the order hasn't been pulled.

I would get as much gear as the factory offers, but that's just me!

bruins004

Yea it seems cheap enough to do and I think I am going to add it.
Just wanted to get the info from all of you guys first since everyone here knows the up and up.

Since the 3.31s were getting around 13.7 - 13.9 in the quarter I was guessing the 2.73s would get roughly 14.5 in the quarter.

codeman94

2.73.... should help you pull a higher top speed it you get a tune..

but you won't get there very quick.

Skotty

Are 3.31 already available as an option? Separate from the performance package available later this year?

fritzOSU03

Indeed they are, I've ordered mine with such an option added...

Skotty

Well that's nice. Cheers to that.

Five Oh Brian

Gears are a torque multiplier, by definition, and going from 2.73's to 3.31's yield 21% more leverage. Therefor, a stock '11 V6 with 3.31's and 280 lb ft torque will accelerate comparably to an '11 V6 with 2.73's that has a bump in torque up to 340 lb ft.

cinque35

Definitely change your order and get the 3.31's!!!

Skotty

That's not exactly true. For the sake of argument, assume some aftermarket shop went crazy and developed a 8.19 rear axle ratio. That's 200% over the stock V6 2.73. If you were to install it in a V6, it would not be like having 840 torque.

Ultimately, it comes down to pushing the car from the rear tire treads. I think the main thing a higher ratio axle buys you is the ability to keep the motor turning as close as possible to the peak torque RPM.

I bet if someone were able to develop a CVT transmission and set it to keep the engine running at the RPM of peak torque, you would achieve maximum thrust and changing the rear axle ratio would have no impact on acceleration.

David Young

Get the 3.31 gears. I ordered my V-6 with them. I read in a road test with the 3.31 gears the engine is still only doing 1,800 r.p.m. at 60 m.p.h.

laserred38

If I were getting a V6, I'd get the MCA pkg, then upgrade to the GT brakes and 3.73s at delivery.

Bert

hmmm . . . then it also follows that it is 21% less fuel efficient because it's always running at 21% higher RPM?

I think we need Doug to do some gear / torque / speed curves for us . . . I get the idea that the higher gear ratio increases the torque at the rear wheels when you are comparing 1st to 1st, 2nd to 2nd, etc. . . . but we don't drive around in the same gear all the time; we shift gears to match the situation; won't there be lots of situations where the car with the 2.73 rear will be at high RPM's in first while the 3.31's will have shifted to second and the 2.73's will actually be delivering more torque?

I do get that the higher rear gearing will generally be quicker in the 1/4 mile because you will keep the RPM's up while also keeping the torque multiplication up . . . but it also depends on how quickly you shift since there might be an extra shift involved . . .

Anyway, I'm still wondering whether the lower gearing would realy make a noticeable difference in street driving; whereas I think the higher gearing will give a noticeable difference in gas mileage???

EDIT -- after doing a little more reading -- I'm convinced that the 3.31's are the way to go, with minimal efficiency penalty for the improved performance . . . here is a quote from TheMustangNews test drive report, which from the pictures was based on a Performance Pack V6(though it isn't 100% clear whether the mileage results were from the PP car or a different car):

And since we are talking efficiency, Ford sent the press out on a driving loop to test the 2011 Mustang V6’s efficiency. A prize was given out to the journalist who achieved the highest mpg. We pushed the car hard and fast wanting to see how the automatic performed, admittedly scuttling our chance at winning the contest. After some hard full throttle sprints at stop lights and a high-speed freeway romp during the 15 mile loop we still achieved a 27mpg combined city/highway cycle. Other journalists who made a true effort at hyper-miling achieved 32-33 mpg combined city and highway. That is actually quite astounding.

EDIT #2 -- a contradictory write up from the recent Edmunds Insideline article:

Of course, you'll get nowhere near that kind of fuel economy if you're using the V6 up near its 7,000-rpm redline all the time. In fact, during our two weeks with this very blue Mustang, we averaged just 20.7 mpg, which ain't bad, but it ain't gonna pass any Priuses at the pump. At least it runs on cheaper 87 octane regular. We should also mention that we averaged about 26 mpg on pure highway runs.

EDIT #3: on another closer read, it seems the high mileage numbers above were from an automatic car, not the PP car . . . so the high mileage is with the 2.73 gears; the lower mileage is from a test of a PP car when they were revving the heck out of it . . . so between the gears and the driving manners the mileage takes a big hit . . . my mileage may vary . . .

hmmmmmm . . . .

Five Oh Brian

Guys, steeper gearing is a torque multiplier - it is a basic law of physics. The problem, though, when you go to extreme gears (like Skotty's mention of the fictitious 8.19 gears) is that there is a diminishing marginal return as steeper and steeper gearing has higher parasitic losses in power just to turn them. However, when we're discussing small steps (3.31's vs 2.73's, in this example), the increases in torque multiplication isn't offset by much parasitic loss. Keep in mind that nearly every drag racer that has put 4.10's to 4.56's in their Mustang that came with 3.XX gears will tell you that there is a very measureable improvement in ET's at the drag strip. Empirical results don't lie, nor do laws of physics.

orange3.9stang

You will only feel the difference between 3.31 & 2.73 from a dead stop, but once moving and up in the power band I would think the torque feel in each gear would basically be the same just at 21% less MPH with the 3.31's.

If you are going to go the drag strip on a regular basis or do a lot of illegal street racing and are rarely out on the interstate doing more than 60 MPH, I guess the 3.31's would be the way to go ... and your crusing RPM's in OD will still be 3% less than a '99-10 V6 MT.

But if this car will be a daily driver seeing 75 MPH pretty regularly the 21% RPM reduction up in OD will be a BIG plus.

I've said this before ... The 2011 V6 MT with std. 2.73 gears off the line will have identical torque multiplication (within 1%) as a 1999-2004 V6 MT with std. 3.27 gears. This was way too much torque for the stock open differential & touring tires but in my opinion just about perfect with a T-Lok and decent performance tires. The 2011 does weigh about 300 lbs more than a '99-04, but there should be more torque at lower RPM's thanks to the variable valve timing so I'm hoping the off-the-line feel will be about the same if not a little better than my '04 which I am completely satisfied with.

In my opinion, the '94-04 V6 MT Mustang's main weakness as a daily driver is 55 MPH & up passing power out on the road. The '99-04 Split-Port was a major improvement over the '94-98, but still not good. I think the 2011 with it's nice power band will have finally adressed this.

--------------------------------------

Now if you want to compare a 2005-10 V6 MT to a 2011, you will be loosing 7.1% torque multiplication off the line with the 2.73's or gaining 12.6% with the 3.31's.

I've never driven a '05-10 V6 MT so I can't comment on the off the line feel, but with the std. open diff. & touring tires it had to suffer from the embarassing "one-wheel-peel" just as bad as a '99-04 !!

If you're an '05-10 V6 MT owner and have added T-Lok and some other performance enhancements and are concerned about maybe loosing a little off-the-line feel, the 3.31 gears would be a wise choise. You should still see an improvement in Cruising MPG thanks to 3% lower RPM in OD and all the other efficiency enhancements.

Doug

fritzOSU03

On the other hand, according to the specs, the V6 maxes out it's torques at 4250 RPM and the 3.31 might keep you closer to that peak depending on what speeds you see regularly. Could easily go one way or the other depending on your preference. I do a lot of interstate driving (75-85 MPH) so the 3.31 is not an economical choice for me; it's a fun one...

Ltngdrvr

One thing I have seen throughout this thread is the incorrect use of the terminology of "higher ratio" when referring to the 3.31 over the 2.73 gear.

The 3.31 gear is not a "higher" ratio, it is a "lower" ratio than the 2.73 gear, it is a numerically higher number but is lower in ratio.

Sorry, just one of the things I see on lots of different discussions about gear ratios that always bothers me.