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Sticks 08-30-2010 05:28 AM

Realistic cost of regearing?
Wife'e jeep is an '06 LJ, 4.0, 6 speed manual, OEM tire size, 2" lift.

Living in Denver, even the slight inclines we have around town and in the foothills are enough to cause the Jeep to loose speed in 6th running 65+ mph. Pretty much runs in 5th all the time and occasionally has to downshift to 4th on some hills (have not taken a trip into the mountains yet, so I know that holding the speed limit is not gonna happen).

I have no clue what axles are under it. I know the front diff cover is round/circular, can't remember if the back is the oddball shaped cover.

Anyhow, running 65mph in 5th holds the engine around 3k rpm. I am guessing the axles are probably 3.73.

Eventually the wife will be towing a 2k# pop-up camper behind it. Once that happens, I know she is going to loose even more holding power, even on the flats.

Aside from installing an under-drive unit (not even sure it would fit, but would be cool to have a 12 speed). Most of the outer city highway speeds are 75mph. Having the engine purring along at 3200 - 3700 in 6th at that speed would be fine.

What gear ratio should we be looking at?

What should I expect to pay to have it done?

What kind of impact are we going to see fuel economy wise (running unloaded)?

4Jeepn 08-30-2010 05:51 AM

What size tires will you be running? Rear should be dana 44. I would say for the money you will be spending if you have 3.73's you will want to jump at least 2 gear sizes so 4.56, but that usually is for 33-35's tires. I had a TJ with 4.56's and 35's lifted etc. got about 14mpg on the highway with the 5spd. gear install figure 1000 to 1500 depending who does the work. Ask how many they have done. what the warranty is from them etc.

Neil F. 08-30-2010 06:07 AM

There will be a label plate attached to two of the bolts on the front and rear differential coves with the gear ratio stamped on it.

Jerry Bransford 08-30-2010 09:12 AM

Guaranteed he has 3.73 gearing, no need to look at the tag on the axles. All non-Rubicon Unlimiteds come with the Dana 44 rear axle which always comes with 3.73.

With stock size tires, the lowest ratio I would go for is 4.10 which is not enough of a ratio change to warrant the typically $1100-1200 cost to regear. For that cost reason, I would only bother to regear when you get to 33" tires where you can make a bigger ratio jump to make spending that kind of $$$ worth it. :)

Sticks 08-30-2010 12:51 PM


With the altitude that the Jeep is driven at, and ultimate towing, the 4.10 may be worth it. It will never pay for itself in fuel savings (if any) but will make driving less frustrating.

It will be staying with the stock tire size - 31 or 30" (can't remember)

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