Gear ratio 4.46

[philown]

Hi,

This topic may or may not have been answered. I know so little about transfer case that I don't even know how to search if this was answered due to lack of proper terminology.


When you get a 4.46 differential; is it only the first gear that is 4.46 and the rest stay the same as a 3.7? Because I'm wondering how will be affected the 6th gear and if I'll get really bad fuel consumption. I do a lot of highway...

I saw 4.46 is on my special order but I don't recall requesting it but, I was actually regreting not taking the locking differential and it comes with it... so I won't complain. But I would have prefered a 3.7 that locks over the 4.46.


Thank you

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[Boreal]

By the sounds of it, you have the MT. But it would help if you shared your build spec

4.46 Gearing is a pretty versatile set. It doesn’t effect a single gearratio in the transmission or transfer case, but it offers a total driveline reduction at the axles/wheels. (Forgive me if I mix stuff up, currently at work). The gear set doesn’t determine the locker.

With 4.46 gears and 30” tires, at 100km/h(60mph) in sixth I found it slightly overgeared, cruising at a cool 1800rpm or so. Now I’ve stepped up to 33” tires, and I’ve found it to be ever so slightly under geared, running into boost at cruising speeds bit more often than i’d like. There is more economic hit from the excess rolling resistance and unsprung weight rather then the gearing.

 

[philown]

first of all Thanks for the reply

So a 4.46 or a 3.7 isn't something that is happening in the transfer case. It is directly applied to driving shaft ?

I ordered big bend 2.3L Manual non SAS 4 doors

 

[philown]

Would you say a specific différent gearing would be better for fuel economy ?

 

[NC_Pinz]

The 4.46 gearing is in the differentials. It has no bearing on the transmission ratios.

 

[PWillette]

first of all Thanks for the reply

So a 4.46 or a 3.7 isn't something that is happening in the transfer case. It is directly applied to driving shaft ?

I ordered big bend 2.3L Manual non SAS 4 doors

The gearing is in the differentials...your wheel will make one complete revolution for every 4.46 drive shaft revolution.

 

[RagnarKon]

Alright so you have multiple gear ratios in play here:

• Transmission gear ratio
• Transfer case gear ratio
• Axle (differential) gear ratio

Those combined together to create a final gear ratio. I created a calculator that you are welcome to play around with:

https://www.bronco6g.com/forum/thre...or-for-specific-tire-sizes-axle-ratios.21902/

Generally speaking, the lower the gear ratio the better your fuel economy will be at the expensive of some "get-up-and-go". The higher the gear ratio the lower the fuel economy, but your vehicle will have more capability while off-roading, towing, hauling, etc. I stress the "generally speaking" because it is a bit of a balancing act and also depends on the tire sizes you are looking at.

4.46 is more of oriented away from everyday driving and towards off-roading. Doesn't mean that you can't drive it everyday... that's not what I'm saying at all. It's a good "middle-ground" gear ratio that leans more towards performance rather than fuel economy.

 

[Boreal]

first of all Thanks for the reply

So a 4.46 or a 3.7 isn't something that is happening in the transfer case. It is directly applied to driving shaft ?

I ordered big bend 2.3L Manual non SAS 4 doors

Would you say a specific différent gearing would be better for fuel economy ?

This gear set that we are concerned with (3.7 vs 4.46) lives inside of the front and rear differentials. IMO, 4.46 Gearing will be completely fine as a daily and it will offer you room to size up your rubber down the road. The aerodynamics of this toaster on wheels will affect the mpg way more than the gearing, not to mention how often you live in boost.

There is ALSO a transfer case gear set, the standard transfer ratio is 2.72:1 and the advanced transfer ratio is 3.06:1. This gearing is related to the overall reduction as well… but again, the general vehicle aero characteristics, ride height, rotating mass, and simply how you drive will play a much bigger part to your mpg than the gearing in this scenario. The taller gears will allow your rig to run a pinch higher in the RPMs at highway speed, but because we are boosted, it’s sometimes more beneficial to run higher revs with vacuum… if that makes sense

in short, don’t sweat it! Oh, and 4.46 is standard for the MT, but you get 4.7 on badlands and mansquatch!

 

[philown]

Ok thanks for the explanations especially about the difference between transfer case, transmission and differential. I saw on the web that if you ask for a Lockable differential then you are forced to get the 4.46:1 ratio. And moreover it is standard on a manual transmission. Only the automatic one gets the 3.7 is that correct?

 

[philown]

This gear set that we are concerned with (3.7 vs 4.46) lives inside of the front and rear differentials. IMO, 4.46 Gearing will be completely fine as a daily and it will offer you room to size up your rubber down the road. The aerodynamics of this toaster on wheels will affect the mpg way more than the gearing, not to mention how often you live in boost.

There is ALSO a transfer case gear set, the standard transfer ratio is 2.72:1 and the advanced transfer ratio is 3.06:1. This gearing is related to the overall reduction as well… but again, the general vehicle aero characteristics, ride height, rotating mass, and simply how you drive will play a much bigger part to your mpg than the gearing in this scenario. The taller gears will allow your rig to run a pinch higher in the RPMs at highway speed, but because we are boosted, it’s sometimes more beneficial to run higher revs with vacuum… if that makes sense

in short, don’t sweat it! Oh, and 4.46 is standard for the MT, but you get 4.7 on badlands and mansquatch!

What is being "'boosted"?

 

[1970AMCAMX]

What is being "'boosted"?

Turbocharged in this case

 

[RagnarKon]

Ok thanks for the explanations especially about the difference between transfer case, transmission and differential. I saw on the web that if you ask for a Lockable differential then you are forced to get the 4.46:1 ratio. And moreover it is standard on a manual transmission. Only the automatic one gets the 3.7 is that correct?

There are only three axles available with the manual transmission:

• 4.46 open differential
  • Standard on Base & Big Bend
• 4.46 locking differential
  • Standard on Black Diamond
  • Optional on Big Bend
• 4.70 locking differential
  • Standard on Badlands
  • Optional on all trims with the Sasquatch package (except Base 4-door, Outer Banks, and Wildtrak)

The 3.70 and 4.27 axles are only available with the automatic transmission.

 

[The Pope]

Alright so you have multiple gear ratios in play here:

• Transmission gear ratio
• Transfer case gear ratio
• Axle (differential) gear ratio

Those combined together to create a final gear ratio. I created a calculator that you are welcome to play around with:

https://www.bronco6g.com/forum/thre...or-for-specific-tire-sizes-axle-ratios.21902/

Generally speaking, the lower the gear ratio the better your fuel economy will be at the expensive of some "get-up-and-go". The higher the gear ratio the lower the fuel economy, but your vehicle will have more capability while off-roading, towing, hauling, etc. I stress the "generally speaking" because it is a bit of a balancing act and also depends on the tire sizes you are looking at.

4.46 is more of oriented away from everyday driving and towards off-roading. Doesn't mean that you can't drive it everyday... that's not what I'm saying at all. It's a good "middle-ground" gear ratio that leans more towards performance rather than fuel economy.

I "believe" that you've swapped the wording..... and a lot of people mix this up.

For the Differential, the Numerically Smaller the Number, is the Higher Ratio.... It's weird, but the 3.70 is call a Higher Gear Ratio than 4.46 .

You are correct that the 4.46 is: "the lower the fuel economy, but your vehicle will have more capability while off-roading, towing, hauling, etc."

And

The 3.70 is: better your fuel economy will be at the expensive of some "get-up-and-go".

 

[IDyeti]

@philown I believe the excel spreadsheet in the linked thread will fill in some blanks. I mean it isn't going to tell you the gas mileage but standard logic applies of higher rpm = more fuel consumed. It does allow you to see the mechanical difference due to gearing options.

https://www.bronco6g.com/forum/threads/gear-ratio-speed-calculator-2-3l-2-7l-manual-and-auto.3561/

 

[kodiakisland]

You will be fine with 4.46 gears. Your transmission is geared high enough to not be an issue, even at 80mph. I have 4.46 gears, 33in tires, and don't even use 6th gear as it's just too high, even at 80mph. Besides, you're pushing a brick down the highway. Induced drag will be far worse than top end gearing. You want good gas mileage, stay below 65mph.

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