3.73 gears for '12 V6

[onlycodered]

Hey guys,

I've had a few recommendations for you and I will be looking to put 3.73 gears in my '12 V6 at some point, unless you would recommend something else. I would like to to some 1/4-mile races at some point. I have the manual 6-speed Getrag MT82 transmission.

The 3.73 gears may not be best as I want to get the best acceleration yet I don't want to end up having to shift right in the speed trap. Let me know what your suggestions would be. I have an axle-back exhaust right now and plan on adding a CAI and 93 race tune at some point but that's about it in terms of future performance mods.

Let me know how much labor would cost for having those installed. Thanks!

 

[EHA Racing]

What gears and rear tire do you have. Is 4th gear 1:1 on that trans? What's the max rpm you would shift at and what trap rpm are you shooting for?
Gear install would be $250 plus parts. No need to change axle or carrier bearings in a '12.

​

 

[ford20]

The MT82 in 4th is 1.24, I know some people (second hand stories) that run N/A cars that have the 3.73s that are just barely making it in 4th crossing the traps at around 6500-7000 with the 3.73s and some people who have 100-150 shots that have to shift into fifth gear (All GT's). I am not sure about the V6 though and what size tire he would be running and what an estimated MPH is.

Just wanted to throw some stories and expierences your way so you can make the best recommendation and have some more info to help you two out.

 

[onlycodered]

My tire size is 255/40ZR19. Perhaps 3.55's would work better then? I haven't run my car yet so I have no idea what the trap speed is but from what I've read from others with the new V6 it would be shy of 100 mph by a few with the 2.73's. I just want to avoid shifting into 5th gear if possible.

 

[ford20]

I just ran some calculations and with your car assuming you hit 100 MPH at the traps with 3.73s your RPM's would be 5749 and I THINK the redline in the V6 is 6000 RPM ( I am probably wrong ) but you still have some room before having to shift into 5th. The 3.73s are good for that.

But also the MT82 in your car as a 4.something first gear ratio which is pretty high so you may want to go with 3.55s just for ease of driveability if it is a DD. But Doug would more than likely steer you in the right direction as to which was the better option. Sorry if I confused you even more lol

 

[onlycodered]

I just ran some calculations and with your car assuming you hit 100 MPH at the traps with 3.73s your RPM's would be 5749 and I THINK the redline in the V6 is 6000 RPM ( I am probably wrong ) but you still have some room before having to shift into 5th. The 3.73s are good for that.

But also the MT82 in your car as a 4.something first gear ratio which is pretty high so you may want to go with 3.55s just for ease of driveability if it is a DD. But Doug would more than likely steer you in the right direction as to which was the better option. Sorry if I confused you even more lol

Oh no you're not confusing. That helped a lot actually. Also, my redline is at 7000 RPM so I feel like the 3.73's might be the best route. A lot of folks with the new V6's have the 3.73's and use them for daily driving and they're fine. I'll be buying a daily driver before winter anyway. Thanks for the tips!

 

[ford20]

Oh ok well thats even better! You learn something new everyday

Glad I could be of some help rather than a hindrance.

If you ever want to calculate your tire size in the future there is a simple formula to use to figure this out.

Tire sizes are usually expressed in XXX/YY/ZZ
XXX - Treadwidth, width of the tire in mm
YY - Aspect Ratio, the sidewall height as a percentage of the treadwidth.
ZZ - Size of the wheel/ rim that the tire is designed for.
Ex. 255/40/19 255mm
[2(.YY)(XXX)/25.4] + ZZ
[2(.40)(255)/25.4]+19
[204/25.4]+19
[8.03]+19

27.03" tire size

I also used this to calculate what RPM you would cross the traps at

Stan Weiss' - Automotive Performance Software / Interactive JavaScript to Calculate Speed(MPH) for given RPM, Rear Gear Ratio and Trans Gear Ratio

I took a guess at the MPH and used 100 since you said that is around the MPH that people usually get with the 3.7L

 

[onlycodered]

Oh ok well thats even better! You learn something new everyday

Glad I could be of some help rather than a hindrance.

If you ever want to calculate your tire size in the future there is a simple formula to use to figure this out.

Tire sizes are usually expressed in XXX/YY/ZZ
XXX - Treadwidth, width of the tire in mm
YY - Aspect Ratio, the sidewall height as a percentage of the treadwidth.
ZZ - Size of the wheel/ rim that the tire is designed for.
Ex. 255/40/19 255mm
[2(.YY)(XXX)/25.4] + ZZ
[2(.40)(255)/25.4]+19
[204/25.4]+19
[8.03]+19

27.03" tire size

I also used this to calculate what RPM you would cross the traps at

Stan Weiss' - Automotive Performance Software / Interactive JavaScript to Calculate Speed(MPH) for given RPM, Rear Gear Ratio and Trans Gear Ratio

I took a guess at the MPH and used 100 since you said that is around the MPH that people usually get with the 3.7L

Awesome! Thanks for all the info! Just looked at a few others who had minimal mods with the 3.73 gears and they're running low 13's in the 1/4 mile with a trap speed of around 110 MPH. I love the new V6! Can't wait to buy these now and have Vanstrom install them!