4.56 gears, 245 75 16's

[Cardhu]

Anybody run the SIFS steel diff with 4.56 and not 32's or larger?

Any expectation of rpms at 65ish with 245 75 16's , worse millage then 245 75 16 on 3.73's?

Just for my own clarity, is the steel diff a dana 30 LP and not a dana 30A? I think thats what i got out of 20 pages of posts circa 2010. Therefore the gears for that diff are dana 30 gears and not 30A?

 

[tommudd]

Anybody run the SIFS steel diff with 4.56 and not 32's or larger?

Any expectation of rpms at 65ish with 245 75 16's , worse millage then 245 75 16 on 3.73's?

Just for my own clarity, is the steel diff a dana 30 LP and not a dana 30A? I think thats what i got out of 20 pages of posts circa 2010. Therefore the gears for that diff are dana 30 gears and not 30A?

yes correct

 

[Cardhu]

Apparent Gearing Chart

From my best guess at calculating engine RPM with the 42RLE and 245 75 16, its putting RPM at ~2600 at 75, vs 2500 if you were running 32's.

The gut feeling from most on here as 32's would prefer 4.56's and 4.10's would be best suited to "31's". If i'm going to go through the trouble of regearing and moving to the steel diff, would seem silly to want to do it twice. least it would give me the option of 32's later and have to do nothing, or atleast be able to tow in style.

More to the point, the engine prefers more higher rpm then lugging, at what point is it screaming and mileage taking a real dump. I would prefer to still be able to drive on the highway for 400 km without needing a gas can.

 

[tjkj2002]

My 3.7 likes 2800-3000 rpm's on the highway,it gets the best mpg's in that rpm range.

 

[ridenby]

3.7 seems to enjoy being wound tight. 4.56 or 4.88 would have been my choice.

 

[tommudd]

I'd be REAL happy with 4.56s
:rockit:

 

[tjkj2002]

I'd be REAL happy with 4.56s
:rockit:

Yeah 4.56's and 32's would have been about perfect.