3.39 gear ratio change

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Rayme20

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I saw on another post it is possible to switch the gears out in the non pp sho to 3.39, and I have a couple questions regarding this. I am currently running 12.7s in the 1/4, how much difference would this make? Also the only 1 I really trust to tune my sho is Livernois, is this type of work that they will do? And will they do it for around the same price quoted on the other post of $3000?
 

Livernois Motorsports

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Yes, it is possible. You would be altering your trans, center diff, rear diff, along with tuning. However, you are talking about a metric ton of money to do so for very, very little gains. The actual measurable performance for the 2 setups are almost no different. I would even venture to say that at big power levels, the standard car is actually better. Even if only by a small margin.
 

krewat

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Is there a 3.39 gear available for the 6F55? I thought it was only the 6F50s...
 

Rayme20

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So as the HP goes up the gears mean less? I have a friend that has a stock 2006 mustang that has nothing but 4.10 gears in it and he runs high 12s low 13s, for him the gear swap was good for about half a second. Figured the same may be true for me, but I realize there are many factors I don't understand that's why I asked
 

Livernois Motorsports

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There is only one set of powered wheels with more displacement. There is not enough displacement in the 3.5L to power through the extra gearing on both drive axles.
 

SilverSH0

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So as the HP goes up the gears mean less? I have a friend that has a stock 2006 mustang that has nothing but 4.10 gears in it and he runs high 12s low 13s, for him the gear swap was good for about half a second. Figured the same may be true for me, but I realize there are many factors I don't understand that's why I asked
With the SHO you're also comparing 2.77 to 3.16 gear ratios (I believe those are correct but not 100%). Likely your buddies Mustang changed from something in the low 3's or around 3.20 to 4.10s. Just like in the Mustang there's not a huge gain when switching from 3.73 to 4.10 gears.
 

92BlackGT

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There is only one set of powered wheels with more displacement. There is not enough displacement in the 3.5L to power through the extra gearing on both drive axles.

wut? shorter gearing multiplies torque more... easier for the engine to turn the wheels. and what does displacement have to do with anything?
 

Livernois Motorsports

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Okay, so I will use your logic to prove that too much gearing is a bad thing.

If you look at all of the quickest (not more powerful) 4th gen SHO's they are all NON-PP cars. Why? Because the 3.16 gearing requires the transmission to shift at about the 1100' mark. Thus, slowing them down. So, even more gearing would result in even earlier shifting, and worse performance still.

As for displacement, you have to have torque to power through gearing...? For example, you would not install 4.10 gears in a Fusion because its lack of displacement would lead to not having enough power for your gearing.
 

SilverSH0

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Gears are simply a torque multiplier. A S2000 has 4.10 gears (that people Will swap to 4.77 gears)with only a 2L engine and no torque. Higher gearing makes it easier for the car to move itself. That's why accelerating in 1st is easier than 4th. It's why of road vehicles that don't have power and big engines swap in higher gearing. Its why it was common in the mustang world to run 4.10 on a NA motor and 3.73 with boost (boost usually has the extra power to make up lower gearing).

The shifting and speed I'll believe. But needing more displacement and torque for larger gearing is backwards because it makes it easier for the car to move at a given torque from the motor.
 

Livernois Motorsports

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I will let these videos speak to the differences in your example and what we are talking about:

S2000

Taurus SHO

Apples to oranges. Does anyone realize that this is a 4 year old thread? Even the dealership that tried to say this was possible realized that it is absolutely fruitless. There is nothing to be gained by trying this. The investment will be far too great for literally a couple hundredths.
 

brucelinc

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This "swap" makes absolutely zero sense in terms of cost, benefit or labor involved.

There has been quite a bit of discussion about drag racing results and how the PP stacks up against the non PP. The results do not lie. The non-PP cars do as well or better. However, there is a difference between drag racing results and street performance results. For a normal street start without brake boosting, the deeper 3.16 gear should have an advantage over the 2.77 at least through low gear. When stock, neither will have a traction issue and even when tuned, wheelspin is minimal on good pavement.

Interestingly, the new Lincoln Continental with the 400 HP engine will come standard with a 3.39 gear. I am not sure what gear will be in the Fusion Sport but the MKZ with the 400 HP engine has a 3.16. Of course, Ford is not equipping these vehicles with drag racing or tuning in mind. Also, the 400 HP 3.0 engine has a different torque curve than the ecoboost 3.5.
 

SilverSH0

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I was not debating speed at all and i thought that was pretty clear. I was saying that the statement about needing torque and displacement to run larger gears is bunk. Larger gears are run in many vehicles with less displacement and torque to make up for the lack of torque. The S2k was simply one example of a smaller displacement motor, with less torque using larger gears. Low range in a 4x4 transfer case makes it easier for the vehicle to move itself and that's roughly equivalent to increasing your gears.

Again, not talking speed. That had a whole slew of factors such as when the car shifts in the track, tire size, and race distance (just as examples).
 
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Livernois Motorsports

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It is not bunk. You are comparing 2wd cars to a car that is has to be able to divide the gearing evenly. That additional division requires more power. That power requires displacement. You would actually slow a 4th gen SHO down if you tried to take a crazy steep gear and install it. You are ignoring the most simple aspect of the mathematics. The FWD biased SHO would not be able to power through 4.10. The upgraded converters would eat up so much power that performance would die. If this were not so, why would this have been a dead thread? The goal is not to argue, but you have to concede that the SHO is not a Mustang. You cannot apply conventional modification to it.
 

SilverSH0

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It is not bunk. You are comparing 2wd cars to a car that is has to be able to divide the gearing evenly. That additional division requires more power. That power requires displacement. You would actually slow a 4th gen SHO down if you tried to take a crazy steep gear and install it. You are ignoring the most simple aspect of the mathematics. The FWD biased SHO would not be able to power through 4.10. The upgraded converters would eat up so much power that performance would die. If this were not so, why would this have been a dead thread? The goal is not to argue, but you have to concede that the SHO is not a Mustang. You cannot apply conventional modification to it.
Again, 4wd vehicles that have small engines with insufficient torque use high gears. They do this to make up for lack of torque and power.

You keep bringing up speed but that's not what I'm talking about.I'm not talking speed of the SHO, I'm talking about simple gearing and great ratios. How gearing works is not car specific, it's physics. How gearing performs in a vehicle is car specific and is an output of the total system effect.

You say I'm ignoring the most simple aspects of the mathematics so please break it down for me in math terms to show increased gearing requires higher input torque to output the same original torque. I work well in math tem so I'm anxious to see what I'm missing.
 

sholxgt

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In the past, I picked gear ratios based more on the top end than anything. Nothing worse than having to up shift right at the finish line.

Looking at the gear ratio options with the factory 20" tires (28.7") tall is interesting.

Here's what the car can do in Third gear depending on gear ratio...
Engine Speed (RPM) MPH 2.77 Gear MPH 3.19 Gear MPH 3.39 Gear

7000 RPM 117.14 MPH 101.72 MPH 95.71 MPH
6500 RPM 108.77 MPH 94.45 MPH 88.88 MPH
6000 RPM 100.40 MPH 87.18 MPH 82.04 MPH
5500 RPM 92.04 MPH 79.92 MPH 75.20 MPH

Here's what the car can do in Fourth gear...
Engine Speed (RPM) MPH 2.77 Gear MPH 3.19 Gear MPH 3.39 Gear

7000 RPM 152.59 MPH 132.50 MPH 124.69 MPH
6500 RPM 141.69 MPH 123.04 MPH 115.78 MPH
6000 RPM 130.79 MPH 113.57 MPH 106.87 MPH
5500 RPM 119.90 MPH 104.11 MPH 97.97 MPH

Everyone is welcome to draw their own conclusions from the numbers above, but it looks to me like a non-PP car with light mods can finish in third gear while a PP car requires an up shift into fourth. That would likely make the 2.77 geared car faster. That is provided that it has enough torque and traction to get an equal 60' time.

It also tells me that a high power SHO would likely be best off with 3.19 gears and finishing in fourth gear.

All of this data is speculation since I haven't run my car at the track yet. You track guys...what gear are you in when finishing the quarter? Will the car let you ride out third long enough to cross the beams?
 

92BlackGT

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Okay, so I will use your logic to prove that too much gearing is a bad thing.

If you look at all of the quickest (not more powerful) 4th gen SHO's they are all NON-PP cars. Why? Because the 3.16 gearing requires the transmission to shift at about the 1100' mark. Thus, slowing them down. So, even more gearing would result in even earlier shifting, and worse performance still.

As for displacement, you have to have torque to power through gearing...? For example, you would not install 4.10 gears in a Fusion because its lack of displacement would lead to not having enough power for your gearing.
i'm not debating that a SHO is fast because of where it shifts, i'm debating your statement about more power required and more displacement. displacement has nothing to do with it. a 2 liter engine can have the same torque curve as a 5 liter engine and that 5 liter will not "power through the extra gearing" better or faster. and, again, lower gearing makes it easier for an engine to turn the wheels so less power is required
 

brucelinc

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All of this data is speculation since I haven't run my car at the track yet. You track guys...what gear are you in when finishing the quarter? Will the car let you ride out third long enough to cross the beams?

My car has the 2.77 gear and will run around 107 - 108.5 in the quarter. It shifts at 6200 and does so before the end of the quarter mile. I would never hold 3rd gear to the end. It is likely the rev limiter would kick in but even it if didn't, those last few hundred RPM would be slow in coming and would exceed red line.

Actually, I am not so sure that a shift slows things down so much. With the Livernois tune, the car shifts so quickly and firmly, a shift actually provides a bit of a lunge forward. I have been in races where we were side by side through first gear and when mine shifted to 2nd, I would jump ahead by 1/2 car length or so due to the quick firm shift.
 

802SHO

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Nothing like coming back 8 years later to say….YES IMG 0720
All that’s needed is the pinion gear set to go along with the ring gear and with some tuning it’s 100% doable! You guys just listened to the self proclaimed internet experts that it couldn’t be done, or that it would cost way too much money and/or it’s not worth it! Why would raising rpm and increasing acceleration not increase performance, in any vehicle let alone ours?

If you don’t care about mpg and don’t need a top speed over 150…what’s there to complain about? Seems like all proven performance gains somehow don’t transfer over to the EcoBoost SHO….according to internet experts anyways

This set is sitting on my table of trans parts ready to go in!IMG 0718
 

Jordan_R

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Nothing like coming back 8 years later to say….YES View attachment 89858
All that’s needed is the pinion gear set to go along with the ring gear and with some tuning it’s 100% doable! You guys just listened to the self proclaimed internet experts that it couldn’t be done, or that it would cost way too much money and/or it’s not worth it! Why would raising rpm and increasing acceleration not increase performance, in any vehicle let alone ours?

If you don’t care about mpg and don’t need a top speed over 150…what’s there to complain about? Seems like all proven performance gains somehow don’t transfer over to the EcoBoost SHO….according to internet experts anyways

This set is sitting on my table of trans parts ready to go in!View attachment 89859
Haters will say it's fake
 

Dmason18704

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I saw on another post it is possible to switch the gears out in the non pp sho to 3.39, and I have a couple questions regarding this. I am currently running 12.7s in the 1/4, how much difference would this make? Also the only 1 I really trust to tune my sho is Livernois, is this type of work that they will do? And will they do it for around the same price quoted on the other post of $3000?
Yes amount of power does play a part in it but how much is directly correlated to the other ratios its working with. Ie a trans with alteady shorter gears an upping ur final drive higher 227 to 316 will always accelerate faster to a cetain speed. U put a set of 593 on a 4 speed ur gonna get to 45 extremely fast but will it help ur 1/4 mile no cuz its screaming 6k rpms in 4th gear maxing at 70 mph.. from the small amount ive seen of these trans gear ratios id say the .3 is the absolute most u could think to gain in the 1/4 an with the sheer cost of doing that swap you could likely get much better gains for less doing other upgrades (unless ur either fbo or very close to it currently)
 

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