Rear Locking Diff / Drive Ratios: 3.73 vs 4.27?

VTBronco

Big Bend
Well-Known Member
First Name
Sam
Joined
Jul 29, 2020
Messages
89
Reaction score
234
Location
Vermont
Vehicle(s)
Honda Civic
Hi all, I’m going to short and sweet.

I don’t know anything about drive ratios. I’m getting the BB 4door. I live in Vermont so I deal with ice and snow. There’s the option to get the real locking differential on my BB build.

What would the real locking diff + 4.27 gearing be useful for? Quick online reading indicates the 4.27 gearing will provide more torque but a lower top speed. If this is correct, how drastic is this? For a daily driver, should I just skip both the locker/gears? I won’t be doing much off-roading, if any at all.

Any info on this topic would be appreciated. Thanks!
 

colintrax

Well-Known Member
Base Sponsor (Level 1)
Joined
Jul 11, 2020
Messages
169
Reaction score
405
Location
Georgia
Vehicle(s)
Chevy Colorado, Ford Explorer
3.73 means the driveshaft spins 3.73 rotations for 1 rotation of the tires. 4.27 is well, 4.27 rotations.
Get the rear locker.
Ratio is up to you. 3.73 will get better gas mileage, 4.27 will have more punch and might get more life out of the transmission. Top speed is gonna be limited by the computer. These aint gonna be race cars.
 

Austin26

Base
Well-Known Member
First Name
Austin
Joined
Sep 27, 2020
Messages
777
Reaction score
1,145
Location
Houston, Texas
Vehicle(s)
2019 Subaru Crosstrek
I did the math breakdown of rpms versus speed for various configurations of wheel diameters and rear end gear ratios and if you vary wheel size it can get a little more complicated but I found there to be a negligible difference in the 10-spd auto at least. I did this for highway fuel economy concerns, not for weather really like you stated. With traction control though neither should matter and it would kick on if you're sliding around on ice or losing traction somehow. It's just a torque multiplier.

Overdrive for the manual is almost exactly the 10th gear (auto has two overdrives for some reason) ratio FYI.

Basically, either shouldn't vary engine rpm in the last gear more than a 100-200 rpms which isn't of concern in my opinion. Don't worry, I worried about this with my Mustang back when I was a kid and was doing the same thing. The only difference was going from like 3.55s to 4:10s in a manual had me at like 2750 rpms at 70 lol.

This smart kid explains it well:
 

Incognito

Base
Well-Known Member
Joined
Aug 19, 2020
Messages
993
Reaction score
2,293
Location
Phoenix
Vehicle(s)
2017 jk
The 3.73 will give better mpg highway.
The 4.27 will accelerate better, so city mpg will be better.
Your call .

Don't use the locker in ice and snow.
You will instantly spin the rear downhill, or sideways into the ditch.

If the model you are buying allows the Advanced transfer case, get it.

The active 4hi mode will be much safer than 2 wheel drive on pavement in winter.
In layman's terms, it works like a Subaru full time 4wd.
 

Advertisement







 
Ridergraphix


Advertisement
Top