2013 convertible 3.7 automatic gears

[cdenigris]

Hey guys,

I have a 2013 3.7L v6 automatic Convertible. I have had this car for about 4 years and I have 95k on it now. The car has the stock 2.73 rear gears on it. The car has always been incredibly slow to get up to speed, and when I bought it I didn't understand much. In other words bad acceleration. I have done numerous things to try to correct this over the years...

- I have an aftermarket cold air intake.
- I have a pedal commander to improve the throttle body response
- and I have a Bama tune from American Muscle.

None of these things have really improved the acceleration on this car and after reading, people say that I should swap out my rear end gears.

So I have some questions. I called some places and they recommended that I put in the 3.73gears to make the car more fun without gas mileage taking a big hit.

1) How much will this affect my gas mileage? I'm getting about 20mpg combined driving around Long Island NY with the stock 2.73gears.

2) Will my car get less traction if I do this. As this is my daily driver it still needs to have traction in rain and snow.

3) Will it make the car accelerate smoother then the 2.73 gears or will it be jerky as if there is less throttle delay?

I made an appointment to do the gears on Friday the 26th. I really want to know if I'm doing the right thing before I go through with it. Please give me some feedback on this.

Thanks all! Looking forward to your responses.

 

[JimC]

The 2.73 gears are good for MPG, but not a lot of fun with very slow acceleration.

I put the 3.55 in my 2013 MCA convertible with automatic and was very happy with those. Accelerated much better and didn't affect MPG too badly, plus the 3.55 is better with the gearing of the automatic transmission so that you don't shift too quickly out of first gear. The 3.73 is actually a little too much for that transmission gearing. The 3.73 may give you that jerky unsmooth feeling you are concerned about.

 

[Dino Dino Bambino]

Ford watered down the 3.7 V6 automatic into a grandma car by giving it a sluggish throttle response and lumbering it with ridiculously tall 2.73 axle gears so they could brag about it achieving 31mpg on the highway, but that meant the car's top speed was achieved in 4th gear leaving 5th/6th effectively as overdrive gears. It also makes acceleration in each gear feel slow.
The 3.73 gears will transform the your car into the animal it should have been while barely affecting gas mileage. As for the tune, ditch BAMA and go with Brenspeed. Jerky driving has nothing to do with the axle gearing. It's caused by poor throttle tuning and a twitchy right foot.

 

[cdenigris]

The 2.73 gears are good for MPG, but not a lot of fun with very slow acceleration.

I put the 3.55 in my 2013 MCA convertible with automatic and was very happy with those. Accelerated much better and didn't affect MPG too badly, plus the 3.55 is better with the gearing of the automatic transmission so that you don't shift too quickly out of first gear. The 3.73 is actually a little too much for that transmission gearing. The 3.73 may give you that jerky unsmooth feeling you are concerned about.

You make a valid point here on the 3.55 and I appreciate it because I am weighing the pros and cons here. It's not like I get to test drive this before I do the job so I want to do something that is right. I have been using the pedal commander which is plug and play for the throttle body response and I have found the car to be too jerky just with that. I wouldn't want to see that as a permanent part of the car with the gears. I am fearful that the 3.73 will be too much. Then again I think about like my wife's Honda CR-V which has like 4.5 gears but I guess that doesn't matter because its only a 4 cylinder engine. Nevertheless. I am also concerned about the drive shaft because I know this car has a 115mph limiter and I'm assuming that is based on the stock gears. If I go to 3.73 would that be reduced to a lower speed because of the spin time?

Edit Quote Multi Quote

 

[Dino Dino Bambino]

I think the 115mph limiter is in place because of the tires rather than the driveshaft. There's a Youtube video of a guy in a 3.7 V6 breaking his stock driveshaft at ~135mph. Not sure what axle gears he had though but yes, numerically higher axle gears will reduce the road speed at which the driveshaft is likely to break.

 

[David Young]

Ford was the 'first' to sell a car with 'over' 300 horsepower (305) and 'over' 30 miles per gallon (31mpg). To do this Ford had to use a 2.73 rear gear ratio


I ordered my v6 with the optional 3.31 gears. This should have been the standard gear ratio. I had my local Ford dealer install my 3.73 gears and have been happy ever since .

 

[cdenigris]

Ford was the 'first' to sell a car with 'over' 300 horsepower (305) and 'over' 30 miles per gallon (31mpg). To do this Ford had to use a 2.73 rear gear ratio


I ordered my v6 with the optional 3.31 gears. This should have been the standard gear ratio. I had my local Ford dealer install my 3.73 gears and have been happy ever since .

Hows your mileage on the 3.73 and what type of driving do you do? I am in congested NYC metro area. Lots of red lights and traffic.

 

[David Young]

I don't put a lot of miles on my vehicles. It's mostly kind of, in town but not city driving with a few red lights thrown in but a lot of hills. My 5 cylinder Audi (150 horsepower?) got 22 mpg. My Ford Taurus (145 horsepower?) got 22 mpg. My Dodge 4 cylinder (158 horsepower) got 22 mpg. My 2011 Mustang (300+ horsepower) gets 21 mpg. So, I'm getting 1 mpg less than my past 3 cars with over 'twice' the horsepower on my Mustang .

 

[cdenigris]

Alright so I got the 3.55 gears put in yesterday guys and I loaded the BAMA tune that I called American Muscle to make up for me. My initial thoughts are.... MEGA DISAPPOINTMENT. The car slightly has better acceleration but its so minimal that it seems this wasn't worth all the money I just laid out. I mean every other modern car accelerates from a red light smoothly and quickly too, and they aren't supposed to have the power my mustang has. I've driven rental cars that are Fords Focus's and quicker than the stang to get going lol. I'm hoping that its because this tune just sucks and that I can correct this with a proper tune. The acceleration is barely noticeable until I get up in speed. It's slightly smoother through first gear in traffic and parkinglots but after that it's still that jerky feeling the 2.73's always had. I really have to hit the gas to get the RPMs to go up on a short distance quick acceleration which is only something I would do hard if I need to do an emergency merge, which I did once today. I only drove around town today. Lots of in and out of the car at stores so I got roughly 14mpg which is pretty bad but I'm sure that will go up when I do real combined driving all week.

I thought once I did this I would get rid of the pedal commander too for the throttle body response sensitivity but right now it seems that I may need to keep that.

With all that being said it seems the install itself went well and the car is acting normal. No additional noise or anything, this is just a performance thing for me.

The tune could be an issue. I will look into it this week but any other recommendations. Is it me?

 

[Dino Dino Bambino]

I loaded the BAMA tune that I called American Muscle to make up for me.

There's your problem.

 

[JimC]

Get a tune from MPT. That was the best tune on my 2013 3.7 convertible with automatic and 3.55 gears.

 

[cdenigris]

I'm going to look in to the MPT since so many seem to recommend them. I don't like the idea of laying out more money after a tuner with free tunes and gears but I want to finish this job and do it right and enjoy my last 2 years with this car. This bama tune is not only not that quick but its a rough shift on my auto too. I want the thing to be quick and like butter. My wife hates the jolt out of 3rd gear and I'm not fond of it either.