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3.73 automatic

6K views 15 replies 7 participants last post by  El Fufi 
#1 ·
Hello All,

I know there have been a few posts on the various gear ratios out there. Im actually scheduled to get 3.73's installed on my 2012 gt automatic next week; however after reading up a bit im starting to have some doubts. Ive read that it will decrease gas mileage, but how significant is the decrease? Im averaging 19mpg overall right now with most of that being city miles. I do drive 9miles to work everyday but its mostly spent in stop and go traffic. I also do drive on the freeway almost daily, but not for any significant distances. My 2 main concerns are mpg decrease, and also noise level increase. I just installed the Roush axlebacks and love the sound, however if the 3.73s would make them even louder it might get to the annoying level of sound. Any input would be appreciated.

thanks!
 
#3 ·
I have the 3.73 gears on my 11 auto and i dropped a full 2 mpg but i also cant keep my foot off the gas lol the sound didnt change much if anything it helped decrease droan on hwy which is nice my commute is almost identical as yours so this should be pretty accurate for you...the FEW times i driven conservative for a few days the mpg jumped back within a half mpg of what i was getting....still get great mpg for longer hwy trips

---------- Post added at 01:28 PM ---------- Previous post was at 01:28 PM ----------

Btw i have single chamber flowmaster exhaust which is very similar sound as the roush

---------- Post added at 01:30 PM ---------- Previous post was at 01:28 PM ----------

Do the 3.73 and dont look back combined with a tune its best bang for buck mods there is
 
#4 ·
Another question i had was about the tune. Im actually getting them installed through my dealer for 500 installed including the gears. Will they tune them upon install? or will i have to get an aftermarket tune such as BAMA etc? the reason im having them done through the dealer is so as not to void the warranty.
 
#5 ·
If you drive freeway a lot then you will be at higher rpm's than usual which means a loss in mileage, since you do mostly stop and go it shouldn't make much of a difference... Some people have actually gotten better mileage from higher gears because since you accelerate quicker you don't have to get on the gas as much in stop and go.
 
#6 ·
19?? At 60mph I get average 28 and climbing. Mine is a manual with 3.73s. At 75mph I average around 24-25.
 
#7 ·
breheiser said:
Another question i had was about the tune. Im actually getting them installed through my dealer for 500 installed including the gears. Will they tune them upon install? or will i have to get an aftermarket tune such as BAMA etc? the reason im having them done through the dealer is so as not to void the warranty.
dealer cannot calibrate your spedometer for the gears so an aftermarket tune is required...the tune will void warrenty

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86custom said:
19?? At 60mph I get average 28 and climbing. Mine is a manual with 3.73s. At 75mph I average around 24-25.
sounds like you drive like a girl the only way i could get that kind of miledge would be to drive very slow and thats not going to happen....btw your manual car is litter which helps a little with mpg are you tuned?
 
#8 ·
godsdisciple85 said:
dealer cannot calibrate your spedometer for the gears so an aftermarket tune is required...the tune will void warrenty

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sounds like you drive like a girl the only way i could get that kind of miledge would be to drive very slow and thats not going to happen....btw your manual car is litter which helps a little with mpg are you tuned?
Well I have my share of fun on short trips. I have a six hour drive home. So I try to squeeze as many miles as I can on long trips. Yes I'm tuned it helped me about 2-3 miles per gallon. I do drive crazy at times but not stupid.
 
#9 ·
godsdisciple85 said:
dealer cannot calibrate your spedometer for the gears so an aftermarket tune is required...the tune will void warrenty

---------- Post added at 04:11 PM ---------- Previous post was at 04:09 PM ----------



sounds like you drive like a girl the only way i could get that kind of miledge would be to drive very slow and thats not going to happen....btw your manual car is litter which helps a little with mpg are you tuned?
Im pretty sure they can.. They did on my old 04 gt when I had them done.. I realize completely diff car but I'm pretty sure you can w fords procal tuner at the very least.. They offer it with some of their various performance pkgs..
 
#10 ·
11stangGT said:
Im pretty sure they can.. They did on my old 04 gt when I had them done.. I realize completely diff car but I'm pretty sure you can w fords procal tuner at the very least.. They offer it with some of their various performance pkgs..
they cannot 100% i know from experience...,they said they could at first but they can only change the gears for the manual (only the three options from the factory) but CANNOT on the automatics. The procal can go up two increments i think to 3.55 on the autos but i am not positive, the procal voids warrenty anyway so might as well get a bama or other aftermarket
 
#12 ·
wnt2gofst said:
Best bang for the Buck on an auto is a stall. Do a stall over gears. Stall will drop. 5 on average where gears you may gain .2.
maybe best bang for the buck if all your doing is drag racing but i think for mainly street stuff its not advisable at least thats my experience...not to mention mpg will be GREATLY affected

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Attually i think dr or slicks are best bang for buck drag racing mod
 
#13 ·
godsdisciple85 said:
maybe best bang for the buck if all your doing is drag racing but i think for mainly street stuff its not advisable at least thats my experience...not to mention mpg will be GREATLY affected

---------- Post added at 07:13 PM ---------- Previous post was at 07:12 PM ----------

Attually i think dr or slicks are best bang for buck drag racing mod
Even on the street a stall wakes an auto up. Big time.

Any time your racing a tire is a must. Be it stock or tune or a 3000whp monster.
 
#14 ·
im not looking to drag race or really do any racing at all (aside from an occasional red light to red light). I just hate how the auto feels sluggish, and ive heard new gears really make it come alive. I considered a stall, but since i wont be taking it to a track the investment isnt worth it to me.
 
#15 ·
breheiser said:
im not looking to drag race or really do any racing at all (aside from an occasional red light to red light). I just hate how the auto feels sluggish, and ive heard new gears really make it come alive. I considered a stall, but since i wont be taking it to a track the investment isnt worth it to me.
You just need a tune then really. It wakes them up big time. A stall is great even for red light to red light. Even if not going to a track though.
 
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