Thread: Seventh Gear!
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Old 06-18-2010, 02:49 PM   #32 (permalink)
comptiger5000
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Join Date: Feb 2010
Location: CT, USA
Posts: 544

RaceJeep - '98 Jeep Grand Cherokee (ZJ) 5.9 Limited
90 day: 13.62 mpg (US)
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I'd love taller gearing for my Jeep. I turn about 1825 rpm at 60mph with stock tires and stock 3.73 gears. Going from the small-ish stock size of 225/70/16 to a 245/70/16 (optional size) will get me down to 1750 and give me a little more ground clearance to the diffs for offroad.

If it wasn't for the insane cost and amount of fab-work required, I'd love to swap in a T56 with either a 2.97 1st gear and the super-tall 0.5 6th, or the more common 2.66 1st / 0.5 6th, and regear the axles to 4.56 or 4.88, that would give me a stick, plenty of low end power, and still lower highway rpm (4.56 would be 1560 at 60mph, 4.88 would be 1670 at 60mph). If I kept the stock 3.73s and did that, my off the line power would be lacking a bit, and I'd be dropping out of 6th on most hills turning only 1270 at 60mph.
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Call me crazy, but I actually try for mpg with this Jeep:



Typical driving: Back in Rochester for school, driving is 60 - 70% city
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