I had 3:55's in my '05 and it was ok. I was not thinking when I ordered the 3:73 in this car because I plan to add a blower. With a supercharger 3:55 would have been the way to go.

 

I'm giddy with my 3.73 gears.If you have 3.55's or 3.31's your probably happy with them.

Either way different gears (if your not happy) are available & can be changed.Don't see what the big deal is.

If seconds are ticking away while your shifting your probably doing it wrong!

The way I see it different people different opinions different mods & different preferences.

 

Yup!

As I've stated many times, if you plan on adding moderate to significant power to the 5.0 you want the 3.55's
If you are going to add major power 3.31's are ideal.

Even stock 1/4 mile runs at a good DA track and 3.55's are best since you can hold 4th without hitting a rev limiter.

Honestly I'm not really sure where the 3.73's would be advantageous over the 3.55's in this car (other than in a stock car during a rolling run contest on the street that either goes to 110 mph or up to 130 or so.

On a race track the 3.73's would just mean more shifting and more wheel spin when putting the power down exiting corners in the lower gears. Same reasons you don't want the 3.73's in auto x either, too much shifting, too much wheel spin out of corners.
On any straights that 120 mph is possible, the 3.73's require a shift to 5th to get up to 120 mph, which costs time and acceleration because from 111 mph to 120 mph a 3.55 car will accelerate harder in 4th than a 3.73 car will accelerate in 5th. And since the 3.55 car can hit about 120 mph in 4th it will be accelerating harder and save the time needed to shift to 5th.

The 3.73's probably feel awesome as lower gearing gives that feel of multiplied torque and more of a push, and for many that's great. But 3.55's are IMHO (and many others who plan to mod and/or race this car) the best gear option for the 5.0)

 

You must not be watching drag races on espn.

All other things being equal, if one car reaches the quarter in 3 gears - rather than needing 4 gears - which car wins?

 

Your right....but again thats only in the 1/4. Its not going to be anywhere close to seconds unless you are retarded. Its going to be tenths.

 

Just because it can make it thru the 1/4 in 3 gears it does not mean it will be in the power band as quickly as the steeper geared car.

Maybe we should all put 2.73's in.

 

Right...

Right... that's why I said all other things being equal.


I just know that as fun as the Bullitt is on 2 lane twisties with 3.73's/Tremec 5spd, Ford engineers also tweaked the ECM & raised the redline to 6500 just so the B would finish the qtr without needing to shift to 4th - like 05-09 GT's with 4.10's have to. Obviously they chose the stronger 3.73 rear end from the KR GT500 because the 1/4 is an important aspect of the car's stock performance (for 2008).

But it looks like 4th is needed for the new 6spd regardless.

 

No, we should put 4.88's in because we will rip through the power band like a stabbed rat!

Am I doing it right?

 

does anyone happen to know what the installation cost would be to put in 3.73s?

Thinking of changing from my 3.31s. I know the new gears would be $180 themselves but didnt know how much it would cost to install them at a Ford dealer.

 

Great thread with some great info in it ... thanks guys.

I've been thinking that my 5.0 will have 3.73's in it when I do finally order it, but now I'm really thinking 3.55's ...

It won't be a drag car, it will be my weekend toy, and don't think I need the 3.73's for that ... it seems to be a very small difference going from 3.55 to 3.73, except some extra shifting at lower speeds and maybe an extra shift in the 1/4, which is not where my car will live

 

Agreed

Were talking about roughly 100 rpm difference in every gear at any speed between the 3 ratio's. And that is nothing to sweat over regarding fuel mileage and how much you shift the car.
I came from the F-body world and had 3.90's installed in my M6 LS1 from the stock 3.42's. The difference in acceleration was great, rpm in every gear changed by about 300 yet it had no noticeable change regarding fuel mileage.
They way the MT82 is geared and with 3.73's it's like having the LS1 T56 with 4.88's and another 1000 useable rpm.
I personally have yet to take the Mustang to the track. I have the 3.73's and I knew of the probable shift to 5th to finish the quarter but I do plan on going with a tune to raise the limiter a few hundred rpm and that should be enough to keep from going to 5th.

 

has anyone went from the 3.19's in the auto to 3.55's? I would think that with the auto 3.73's would be a tad much but 3.55's might be a nice addition.

 

The first 2 gears in the A6 equate roughly to the manual with 373's.

 

Are you talking with the 3.19's??

 

a very good read, thanks for all the deliberation! On just this topic, I rang a buddy up the other day to ask him (SCCA American Iron) about the ratios, and this thread put more particulars to the conversation.

 

I went with 3.55's with the intention of adding FI down the road. Now that I decided to stay NA, I would rather have kept the stock 3.31's and used the money to add in 4.10's.

 

Your car has 3.15 gears from the factory. Gears 123 in the 6r80 are geared to give you the equivalent of a 4.10 in the rear end. And that is a good thing.

 

3.73's rode the limiter in 4th thats why i trapped only 109mph on a 12.57 run

it was like hitting the brakes at the 1000' mark.

i would go 3.55's if i knew then what i know now.. i was under the impression that the gear ratios were going to be the same in the tremec when i ordered it.. when i finally realised what the ratios were i was already given a vin and it was too late to change..

 

What 1/4 mile times should I be expecting on a stock 2012 GT 6MT with 3.31 gears?

 

Hi 12's at 110 mph if you have good traction and can launch/shift well.