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Difference in Speedo After Gear Install

3.1K views 40 replies 12 participants last post by  Diehard  
#1 ·
So my 3.73 gears are being delivered today. Of course I want to get them put in ASAP but Im still deciding if I want to wait for a drive shaft or not...

Anyway, when going from 2.73 to 3.73 gears how much is the speedo off by? I dont have a tuner and to be honest I dont plan on tuning it right now, so Ill have to live with my speedo being off a bit.
 
G
#9 ·
Will you be accelerating really hard or something? If not that or high speeds, I don't think an aluminum driveshaft is gonna give you what you will be spending on it? The MPG change and performance is almost non-existent. Since you have a manual, it would be $700 to get rid of the vibration issue that some of those have. But that is about it.

However, it is your car and you are the Staff here! So whatever choice you make, the rest of us can live with :)

I bought into the Driveshaft gimmick and wish I spent the $700 on some good headers and something else. lol
 
#11 ·
Lol, thanks Kevin and yes Im the staff here so dont make me mad...:angel:

To be honest I feel kind of the same way. Yes the DS has advantages, but will it be worth it for me? I guess I could always add it later like some one else said. I just thought since it will be in the shop getting the gears done they could do the DS too. My gut tells me to wait. Thanks for the advice guys!!
 
#12 · (Edited)
I just went from 2.73 to 3.73. The car was done about 30 minutes before the snowstorm in VA. I didn't want to risk getting stuck while tuning it at the shop so I drove home without tuning it for the updated gears.

My car is a 2014 v6 Automatic. If I remember correctly, the speedo said 70, but my actual speed was 45-50. I'm not sure how much, if at all, it differs on a manual. But hopefully that gives you a rough idea. Since you have a manual, you won't have to worry about the shift points.

-edit for your last post-

Lol, thanks Kevin and yes Im the staff here so dont make me mad...:angel:

To be honest I feel kind of the same way. Yes the DS has advantages, but will it be worth it for me? I guess I could always add it later like some one else said. I just thought since it will be in the shop getting the gears done they could do the DS too. My gut tells me to wait. Thanks for the advice guys!!
I also really wanted the aluminum driveshaft. I wanted to get it installed at the same time as my gears. The shop convinced me that the advantages don't justify the money for my intentions. The first questions they asked me were "do you track the car?" "how often do you need to go over 110mph?" both answers being no/never, they told me not to waste my money and put it towards something else/save it.
 
G
#15 ·
I mean, if you REALLY want the DS then go for it. But the install is soo easy it is stupid. I did it myself. 8 bolts. Thats all that is holding it on. So if it had to wait, you wouldn't be missing out on a 1 time thing.



Sent from my SAMSUNG-SM-G900A using Mustang Evolution mobile app
 
#18 ·
That's a 37% increase in revolutions of your driveshaft and a 37% increase on your speedometer. That a lot more than a bit. You'll definitely show a big improvement on your 0-60.:eek:
 
#26 ·
So I'm kind of in the same boat as the OP. On Tuesday I get my car back with my 3.73 gears and I have a bama x4 tuner that I will use as soon as the shop hands me my keys. When I ordered my tuner they asked me the questions about the upgrades I have in my car and I selected 3.73 gears. My question is, when I install the performance tune (for break in period) will my speedo be calibrated or do I have to do something extra to get it right. I'm totally new to tuners btw. 2014 mustang v6 auto


2014 Mustang V6, Sterling Grey, Borla S Type's, GT500 Spoiler, Boss 302 Strut Bar, MMD Classic Louvers
 
#27 ·
When you selected 3.73 in the tune request sheet, that told the tuner to build the tune for those gears, including the speedo calibration.

Sent from the Death Star.
 
#28 ·
#37 ·
Picked up my car with the new 3.73's installed and immediately plugged in my bama tuner so the spedo would be fine(and it is). The guy said to take it easy for 1,000 miles! He said freeway driving was good for it as well. I'm excited to finish the break in period and see what this baby can do. Fyi I'm at 2600 rpm at 80mph


2014 Mustang V6, Sterling Grey, Borla S Type's, GT500 Spoiler, Boss 302 Strut Bar, MMD Classic Louvers
 
#39 ·
Yeah but 30 mph at what speed?
According to my little speedometer calculator, when you're doing 60 your speedo will read 82 mph.
Or at 65 mph your speedometer reads 89 mph.
Does that sound about right?
Speedometer Correction Calculator