Is anybody running 3.73s with an ax-15 and 31s? What rpm does it run around 55-65mph? How about mpg?

 

http://www.grimmjeeper.com/gears.html

 

Wow! Thanks. It seems to be off by a couple hundred RPMs though. With my 3.07s at 65 mph I run about 1900 and it says it should be just over 1700. Probably not a significant enough amount to cause problems though.
I've been leaning toward 3.73s but I don't want to kill my commutability.
Thanks for your help.

 

I'm running 33's with an AW4 and 3.55's. I think I'll jump down to 4.55's. Getting to 65 is kind of sluggish.

 

^^^
yeah. i'm gettin tired of it too.

 

It's not horrible because I don't have a lead foot anymore, but it seems like it kinda just rolls into OD and not a firm shift. Gears are expensive though. Lol

 

yeah i don't beat on mine either, but ur right its shifting behavior has def changed.
I drive mine 3rd around town. I won't shift it into OD until 50. I won't let it shift into OD @ 40 anymore. I don't want to bake my tranny..haha.

 

I actually need to readjust my TV cable. I adjusted it a couple weeks ago and since then it seems to not like shifting into OD unless I let off the accelerator a hair.

 

Your 31s may not measure 31.

 

^^^
this is true when using the gear calc. i have 33s but they measure out to 32.5
keep that inmind.

 

I guess I never thought to measure. It says 31 so I figured that's what it was.
2200ish rpms on the freeway shouldn't kill my mpgs too bad should it? (Trying to decide between 3.55s and 3.73s)

 

An excellent point. Unless you're measuring by GPS, speedo tooth count, final gearing ratio, and actual tire diameter all mess with things.

3.55s are very good for AX-15 and 31s and are reaally easy to find.

 

these engines are most efficient right around 2100 rpm's so 2200 isn't bad at all.

 

And FYI guys, these engines get the most oil to your cams between 2000 and 2500 rpms. Stop trying to lug them around at 1200.

 

Could be why majority of us have 4.0s that sound like diesels? Too much wear on valve train from too low ROMs/ insufficient oiling?