Best gears for an Auto??

[StangFreak]

I have an auto mustang with a Boss Intake, what gears are my best option? I track the car from time to time not too concerned about mpg.

[cmanley99]

I just made the switch to 3.73 gears...I have not track tested them yet but for day to day driving, I love them!!! I know with the boss intake, you will enjoy them even more as it will help with the low end torque loss. Just make sure you have good, wide tires.

[Mrjeremyt]

What gears do you currently have?

[Dominic Toretto]

How do you tell what gears you have? At 2k rpm I am right at 70mph.

-Alex

[StangFreak]

What gears do you currently have?

4:10s

[Mrjeremyt]

4:10s

Are you sure?? That's the lower gears available from the factory... Most torque in those gears. Why the change? That's a better question, are you looking for low end or all around?

[Mrjeremyt]

How do you tell what gears you have? At 2k rpm I am right at 70mph.

-Alex

There is a tag on the axle if you can decipher it. There is also a vin decoding website, although I don't know what it is. Do you have the window sticker? It also has it...

[kdanner]

3.31 seems to work best up until you trap 126mph or so, then you either need a 30" tire or go back to stock 3.15.

[Dominic Toretto]

There is a tag on the axle if you can decipher it. There is also a vin decoding website, although I don't know what it is. Do you have the window sticker? It also has it...

No window sticker. Car was not purchased new. Guess I could just ask a dealership.

-Alex

[kdanner]

It came with 3.15, they all did.

[Dominic Toretto]

It came with 3.15, they all did.

Thanks.

-Alex

[StangFreak]

Are you sure?? That's the lower gears available from the factory... Most torque in those gears. Why the change? That's a better question, are you looking for low end or all around?

Basically all around I want a good aggressive gear at the track but that's also good for hwy racing.

[Mrjeremyt]

3.31 seems to work best up until you trap 126mph or so, then you either need a 30" tire or go back to stock 3.15.

Mine came factory with 3.31s, and my brothers came with 3.55s... I've also driven a 2012 with factory 4.10s...

[kdanner]

Mine came factory with 3.31s, and my brothers came with 3.55s... I've also driven a 2012 with factory 4.10s...

No 2011+ automatic ever came with anything but 3.15. No 2011+ ever came with 4.10. Manuals are 3.31, 3.55, or 3.73.

[Mrjeremyt]

Basically all around I want a good aggressive gear at the track but that's also good for hwy racing.

I would go with 3.55s, just as a good medium. You won't see extremely excessive gains or losses.

[Mrjeremyt]

No 2011+ automatic ever came with anything but 3.15. No 2011+ ever came with 4.10. Manuals are 3.31, 3.55, or 3.73.

Ya, somehow completely forgot we were on autos.... Wouldn't you have to reset the adaptive values in the TCM if you changed gears??

[StangFreak]

Mine came factory with 3.31s, and my brothers came with 3.55s... I've also driven a 2012 with factory 4.10s...

The 4:10s are aftermarket

[StangFreak]

Are you sure?? That's the lower gears available from the factory... Most torque in those gears. Why the change? That's a better question, are you looking for low end or all around?

I'm not thinking about changing gears just wondering if its the beast option for the A6 with full bultons because if seen some auto with 3:31 running some impressive times mid to lowe 11s. So does that mean if the exact same car with 4:10s would run better?

[kdanner]

I'm not thinking about changing gears just wondering if its the beast option for the A6 with full bultons because if seen some auto with 3:31 running some impressive times mid to lowe 11s. So does that mean if the exact same car with 4:10s would run better?

The problem with a gear like 4.10 and this trans is traction. I did run a 4.30 for a long time and on the rare occasion it would hook it was badass the way it picked up the front end. The 3.31 just made it a better car, it was just as fast, and it goes down the track every time now. Think of it this way, let's go old school C-4 trans, those had a 2.46 1st gear. The 6R80 has a 4.17. So, 4.17*4.10=17.097 ratio in 1st gear. Now try to get a C-4 the same. 17.097/2.46=6.95. You'd agree a C-4 and a 6.95 is a hell of a lot of rear gear right? That's the same you're getting with a 4.10 and a 6R80. Even the stock 3.15 gear is like a 5.34 axle with a C-4. If you wondered why these automatics run so good, right there is a big reason why. Leave the stockers in it, or maybe change to 3.31 to get the very slightest bit more out of it.

[StangFreak]

The problem with a gear like 4.10 and this trans is traction. I did run a 4.30 for a long time and on the rare occasion it would hook it was badass the way it picked up the front end. The 3.31 just made it a better car, it was just as fast, and it goes down the track every time now. Think of it this way, let's go old school C-4 trans, those had a 2.46 1st gear. The 6R80 has a 4.17. So, 4.17*4.10=17.097 ratio in 1st gear. Now try to get a C-4 the same. 17.097/2.46=6.95. You'd agree a C-4 and a 6.95 is a hell of a lot of rear gear right? That's the same you're getting with a 4.10 and a 6R80. Even the stock 3.15 gear is like a 5.34 axle with a C-4. If you wondered why these automatics run so good, right there is a big reason why. Leave the stockers in it, or maybe change to 3.31 to get the very slightest bit more out of it.

What do you think about the 3:55 and you think they trap me in 3rd if raised the rpms to 7700 with the BIM?

[kdanner]

What do you think about the 3:55 and you think they trap me in 3rd if raised the rpms to 7700 with the BIM?

I'd say you won't make it in 3rd unless the car runs a really low trap speed, or unless you put a really tall tire on. 3.31 with a 28" is the best bet for most cars to be able to trap in 3rd. Once you get to like 126-127 MPH, time to start thinking about 3.15 with a 28" or 3.31 with a 30" tire.

[Yagermeister]

I'm not thinking about changing gears just wondering if its the beast option for the A6 with full bultons because if seen some auto with 3:31 running some impressive times mid to lowe 11s. So does that mean if the exact same car with 4:10s would run better?

StangFreak, you're probably thinking of my red auto. Had a Boss intake and 4.10s and always crossed the finish line in the middle of 4th...not ideal. Went to 3.31s and cross the finish line at the top of third saving time to make that last shift, easier to launch, have great gas mileage again (just in time for e85!)

[StangFreak]

StangFreak, you're probably thinking of my red auto. Had a Boss intake and 4.10s and always crossed the finish line in the middle of 4th...not ideal. Went to 3.31s and cross the finish line at the top of third saving time to make that last shift, easier to launch, have great gas mileage again (just in time for e85!)

Oh yeah i haven't gotten the car to hook off the line and the extra mpg wont hurt, this is with the RPMs set @ 7700? If I happen to run into used 3:31s would I have any issues with them oppose to ordering new one from AM ? And can they be set to have a" kick" as I like to say, I like how the 4:10s feel.

Thanks

[Yagermeister]

I shift around 7700 and the kick is all in the tune my friend ;)

[Yagermeister]

Oh yeah i haven't gotten the car to hook off the line and the extra mpg wont hurt, this is with the RPMs set @ 7700? If I happen to run into used 3:31s would I have any issues with them oppose to ordering new one from AM ? And can they be set to have a" kick" as I like to say, I like how the 4:10s feel.

Thanks

Used gears can sometimes be risky due to the wear on them. I'd go new Ford Racing ones purchased from anywhere reputable. As mentioned before the "kick" is in the tune. The 4.10s do have a kick due to the torque multiplication but it'll depend on the goals you have but 3.31s work better for me with what I am trying to do

[kdanner]

I've had no problem with used 3.31 from newtakeoff.com, in more than 1 car. They are $80. It's all about having the right tools and knowing how to use them.

[StangFreak]

Thanks for the info guys :cheers: