Gearing question (1 Viewer)

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EarthX

Owner of Earth Exploration Technologies
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Mar 6, 2005
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After driving around on my 38s I've decided it's time to re-gear. Now all this gearing stuff is a little over my head right now. I hoping someone will help me calculate what gear I need.
The rig is now set up like this:

fj80 axles with 4:11 thirds
stock slit case
4l60e tranny
38" tires

With the 38s I think I'm feeling the tranny slip while driving up hill while under hard power.
I bolted up some 275/70/16 tires I had sitting around and the difference is amazing! Until I re-gear I may run these, even though it looks ridiculous.
What would be the equivalent of the 275/70 in r&p gears?

Someone educate me.:cheers:
 
Perfect. Thanks for the link.
I think you're right, 4.88s seem to be the sweet spot.
 
Ok, after messing around with that calculator a bit more, Im having a had time deciding which would work better; 4.88s or 5.29s. At 70 mph, 4.88s should put me right around 2114 rpms. 5.29s around 2292. Not a whole lot a difference. Im thinking that the 5.29s might make up for that slightly higher rpm with great low range performance. Any thoughts? Does those rpms seem to high for highway use?
 
you start to sacrifice some strength once you move past 4:56. You also may need to ground down your ring on a ratio higher than 4:56 with and ARB.

Ive heard mixed opinions on the strength of 4.65's. I wont be going higher than that and whatever I choose will be cryo treaded, Im not worried about the strength. Also Im runner factory elockers so no ARB for me.
 

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