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3.31 To 3.73 Gear Change????


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Purchased a new 2014 GT500 last August and got to drive it for 10991.6 km (6829 miles) before putting it away for the winter. I am now thinking about changing the gearing from 3.31 to possibly 3.73? As well as accelerate a little harder...I think it will give the car a more usable 6th gear overdrive. The maximum posted speed limit in British Columbia is 100 kph (62 mph) and in 6th gear the engine is turning around 1200 rpm. I was told it is not good to lug a supercharged motor...where I live has lots of elevation changes and 1200 rpm feels too low.

Any replies to this subject would be appreciated!

Cheers

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Edited by konakenny
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The main purpose of the gearing for sixth gear on the 2013-2014 GT500 is to eliminate the gas guzzler tax in the USA. Just keep it in fifth gear. You don't have to drive the car in sixth gear since it

Well technically a portion of your drive-line warranty was voided when the 3.73 gears were installed so no reason to stop now. You will need to go with an aftermarket calibrator tool that is need

I'd be interested to see how you get the power to hook up on the tires with 3.73's.

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The main purpose of the gearing for sixth gear on the 2013-2014 GT500 is to eliminate the gas guzzler tax in the USA. Just keep it in fifth gear. You don't have to drive the car in sixth gear since it is designed to be a real overdrive gear for the highway. Think of it as a five speed with the extra gear. Keep in mind that the stock 0-60 and quarter mile times are where they are at with the 3.31 because there is less shifting involved to get those times.

 

Pete

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nah, go with 3:73. the gears are taller across the board in the '13-14 MY. partly for fuel efficiency and partly for the astronomical top speed (and marketing strategy). 3:73s will make that car more usable and more fun in normal driving conditions (0-100mph).

Edited by 2007tungstenGT500
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Thanks for the replies, it is nice to hear what others think and get different opinions! The car is quite a performer out of the box...long legs and all! Making 6th gear more usable is something I would like as I do a lot of traveling on the highway in the summertime. But most importantly and why I bought the car is acceleration, with 3.73 gears it should accelerate a little harder and have a bit more headsnap. I plan on doing a trackday on the road course track and a test & tune day at the dragstrip (Mission Raceway) every summer.

 

14 GT500...Did changing the gears effect the launch control feature?

Edited by konakenny
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Thanks for the replies, it is nice to hear what others think and get different opinions! The car is quite a performer out of the box...long legs and all! Making 6th gear more usable is something I would like as I do a lot of traveling on the highway in the summertime. But most importantly and why I bought the car is acceleration, with 3.73 gears it should accelerate a little harder and have a bit more headsnap. I plan on doing a trackday on the road course track and a test & tune day at the dragstrip (Mission Raceway) every summer.

 

14 GT500...Did changing the gears effect the launch control feature?

the only effect is how hard it launches :shift: no negative effects

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I remember the difference it made on my 08 Gt500,reading this post made me decide to go talk to my dealer about putting 373's in my 2014. Parts ordered! As soon as the weather here permits, gears in. Hopefully next week or 2

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My 07 has the 373s and soon the 13. It is like driving an automatic around town never leave 1st.

I seem to recall last Sept going through the 1/4 trap in second 107mph and the 1/2 at 13? mph in third. Just too tall of a gear.

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I was asking myself the same question, 3.31 To 3.73 Gear Change? I asked my Ford service technician, who also races his mustang on the weekends. He recommended against it, because he says Ford changed the gearing in the transmission to match with the 3.31 rear end, so they would be in-tuned with one another. Does that make sense, and do you agree with him?

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no. service techs are not engineers. by race his mustang on the weekends he probably means from stoplight to stoplight. ford did change the gearing in the transmission, but it was in conjunction with the taller 3.31 gears in order to achieve the top speed and the fuel economy rating. in other words, the gears in the newer transmission are ALSO geared taller than 2007-2012. how do i know? because my car had 3.31 gears from the factory and it won't do no 200mph...even with 650+ hp. in any event, it's a simple mechanical change. swapping out gears is a completely independent modification that has nothing to do with your transmission. in your case, it will merely result in translating the power from the transmission and velocity of the driveshaft such that each gear in your transmission will feel like it is spooling up quicker but your will not be traveling as fast as before in terms of miles per hour.

Edited by 2007tungstenGT500
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I was asking myself the same question, 3.31 To 3.73 Gear Change? I asked my Ford service technician, who also races his mustang on the weekends. He recommended against it, because he says Ford changed the gearing in the transmission to match with the 3.31 rear end, so they would be in-tuned with one another. Does that make sense, and do you agree with him?

 

According to Ford, they went from the 2.97 first gear to the higher 2.66 on the 13-14 GT500 both to reduce the rear wheel torque on hard launches and to eliminate the shift from 0-60. For me the high first gear with the high rear end ratio makes the car a pain for driving in traffic ( a big consideration in L.A.).

 

I've had my car for a few months now, and I knew in the first ten miles that I would be going to 3.73s. I want the car to be "matched" to my driving conditions. The car will never see 155 MPH (the limit on convertibles) with me behind the wheel anyway so a lower top gear won't matter.

 

With the stock 285/35/20 tires and 3.31 gears the engine is turning about 1400 RPM at 70 MPH, with 3.73 gears it will go up to about 1550 RPM. Not much of a change really, but it will make every gear more useful to me.

 

The only other changes to the 13-14 transmission were that second went from 1.78 to 1.82 and fifth went from .74 to .77. Not that much of a change.

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One of the car magazine (Muscle Mustangs and Fast Fords) tested a 2013 gt500 with stock gears and a gt500 with 3.73 gears (no other mods)....they wrote that the car with 3.73's was .40 faster through the 1/4 mile. The super snake with 850hp gets 3.73 gears! My Boss 302 had 3.73's and driving it around town was great...you could let the clutch out with no gas...when visiting Vancouver, it was much nicer to drive in the heavy bumper to bumper traffic. The ZL1 has 3.73's, uses six gear to reach top speed, has wider tires and better brakes...I wished Ford would have done all that to the gt500. 200mph in 5th gear seems as useless as a 6th gear overdrive that you can't use...unless you live in Germany...lol.

I do get and understand the 0-60 and not having to shift if you are drag racing from light to light...but the penalty for drag racing on the streets here is so severe that it is just not worth it anymore...now I just sit there and scare the hell out of them. :)

 

I LOVE my Shelby!!!

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... 200mph in 5th gear seems as useless as a 6th gear overdrive that you can't use...unless you live in Germany...lol.

Yes, the 50% overdrive in 6th is pretty extreme. A 4.10 rear end may not even be too low, especially if you go up to 305 or 315 on the tires for better traction.

 

 

 

... now I just sit there and scare the hell out of them. :)

Me too! Driving crazy in L.A. can get you on the 6 o'clock news. :)

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Got mine back from the dealer today. I like the 373's much better than the 331. Only thing[which didn't surprise me] the dealer could not calibrate my speedometer so now it's 10 mph off. I'll have to use a sct to get the speedo correct.

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mine as well get one even if you don't use to to reflash the pcm. it's useful for gear ratio changes, tire revolutions (for different wheel/tire combos) and for reading and clearing engine codes. get one used from somebody and you can save $150 over new. just make sure it's "unmarried", meaning the car it was used on has been reflashed back to stock, thus unlocking the device for use with another vehicle.

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I would like to do this mod eventually as well. I had 4.10s in my 03 Cobra and thought it was too much on the highway. So I am curious to see how 3.73s will perform on the freeways.

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I installed the 3.73 in my 2013 Shelby and feel that it is the perfect gear for these cars. I have a 2003 Mach 1 with 4.10's and they are too deep. My Shelby is a blast with these gears.

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Will a gear change void the warranty if a ford dealer installs them?

Good question with no straight answer. it might it might not depends on the dealer. Now if you are asking this question you might want to wait till after warranty. once down the mod road: if it breaks you fix it with your $$.

bottom line is you got to pay to play.

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I would like to do this mod eventually as well. I had 4.10s in my 03 Cobra and thought it was too much on the highway. So I am curious to see how 3.73s will perform on the freeways.

 

I have been giving a lot of thought to this since I got the car.

 

With our very high 50% overdrive in 6th and stock 3.31 rear end ratio, the engine is turning about 1400rpm @70mph (with the stock 285 tires), that makes 6th almost unusable for me.

 

According to my calculations, with 3.73s the rpm would go up to about 1575, and with 410s up to about 1750. Either way, the engine would still be turning slower than my Expedition or my F250 at the same speed.

Edited by Joraft
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Will a gear change void the warranty if a ford dealer installs them?

 

I see a lot of this type of question on the forums. In my younger days I spent several years as a service manager in a Nissan dealership. I can tell you that a new car warranty is offered by the manufacturer, and a dealership has little say in what will be covered and what will not.

 

And unless federal law has changed in the last twenty years, a vehicle manufacturer cannot arbitrarily void a new car warranty because of a lack of maintenance or modifications to the vehicle, UNLESS it can be proven that the failure was DIRECTLY related to the lack of maintenance or modification.

 

If you spin up the supercharger or flash a tune that advances the timing and fry a piston, you're probably going to be on your own for the repair. If you do nothing but change the rear end ratio and fry a piston, a relationship between the two would be impossible to prove, and the warranty could not be voided.

 

That said, if the dealership installs the new gears, the warranty for THAT work should covered by them directly. If an independent shop does the work they would be responsible for any warranty on the installation.

Edited by Joraft
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Not yet, I couldn't figure out how it worked. lol. I'm going to call about it on Monday. I was only out in the country so I didn't really care what the speedo read, I had my foot on the floor the whole time.

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