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Unread 05-07-2009, 06:21 AM   #1
Timothy_90
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Gears

So I think my I6 ZJ has 3.73 gears in it b/c it came with the tow package (correct?), I'm planning on a 3.5 in lift and 31 or 32 inch tires most likely mounted on steel wheels so will I want to re-gear? And if so to what? I'm thinking if I don't it will end up rather sluggish, but if I have to re-gear I'd like to throw in a front aussie locker while Im in there which means I also want to get rid of my 249 and replace it with a 242 or 231. Will it be bearable to drive until I can afford gears at a later date or should I save up a whole bunch of money and do it all at once?

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Unread 05-07-2009, 07:43 AM   #2
WhiteOut
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With 32's and the I6 I would regear, swap in the 242 and simply use the LSD in the rear (if it has one). This also depends on the type of wheeling you do. I have driven both the I6 and V8 and even stock I found the I6 to be a little weak, even stock. I couldnt imagine driving one with a lift and 32's.
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Unread 05-07-2009, 09:00 AM   #3
SnowLeopard
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I'm trying to go the regearing route myself, but it looks to be expensive to get them installed. I think the I6 setup might've been better off with some lower gearing in the first place. Perhaps 4.11. It'd certainly give it more pep where you need it. I know that 4Runners, I know, bad word, come with 3.93 gearing and 31" tires stock. I'm fairly certain that's the case. With a V6 they seem to perform a bit better on the highway, but that's only the '96-'02 models. I haven't been in them enough to really know though. They're 4...runners. Bleh. Has anyone seen how boring the interior is? I was in an '03 and thought it bland. My '97 ZJ has more bells and whistles, and I love having info everywhere. Above head info center, primary information center, a full array of gauges, etc. And it's...a Jeep.

There's really been a lot of discussion on JF about the I6 and its capability lately. I've come to realize I'll sacrifice speed and acceleration for mpg and reliability. I'll definitely regear or swap axles before going to 31's though. I'm actually going to try and lift and swap axles with the 4.11 gearing before getting new tires. If I manage that, I'll share my experience. I'm curious how it'll perform with stock sized tires.
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Unread 05-07-2009, 02:42 PM   #4
StrokedWJ
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IMO, going from 3.73 to 4.10's doesn't make a lot of sense when you look at the cost of regearing compared to the performance gain. I ran 32's and 3.73's for a couple of years and thought it was ok. Of course, I also felt the I-6 has adequate power in the WJ and not do not consider it a dog (I've never driven a V-8). If you currently think the I-6 could use more gearing, you may want to consider jumping to 4.56 gears with the 32's. I ran that combo for a few months before getting new tires. It was a considerable difference over the 3.73's. The RPM's were a tad high @ 70 MPH, around 2500 IIRC.
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Unread 05-07-2009, 03:02 PM   #5
Timothy_90
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I guess once I finally get it all set up with wheels tires and suspension I'll just drive it and see. I'm trying to build it up more in stages really, I don't think my wallet can handle too many things at once. I may end up keeping it limited to 31s but then again one inch in tire diameter probably won't make a significant impact on the final drive ratio and I'm sure the weight difference is negligible.
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Unread 05-07-2009, 03:16 PM   #6
SnowLeopard
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While I'd not pay to regear, if I can find some axles with the gears already in them... Better axles, that is. I'd consider them. That's me, and I hear something different every day on JF. I don't really want to go over 31-32" so I think 4.11 will bring the curve over when I move up in tire size from 29's. I'm still checking my options. 4.56 seems like overkill to go to 31's though. And just so you know, the WJ's 4.7 V8 is nicer than the I6, but it's not until you're in the HO version that you really see the difference. That thing is powerful. I haven't ever been in a 5.9 ZJ though. So it'd be interested to see what it's like. Only the 4.7 V8, even the HO incarnation, takes regular and gets around the same mileage an I6 does, if not better. I was in an Overland fully loaded down, 5 adults and luggage, and we were doing 75 on the interstate and averaging 20-22mpg according to the overhead display.
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Unread 05-07-2009, 03:19 PM   #7
98zjdave
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Quote:
Originally Posted by Fraser_Brown View Post
With 32's and the I6 I would regear, swap in the 242 and simply use the LSD in the rear (if it has one). This also depends on the type of wheeling you do. I have driven both the I6 and V8 and even stock I found the I6 to be a little weak, even stock. I couldnt imagine driving one with a lift and 32's.
Its not as bad as you think it would be. By no means is it quick, but it really isnt all that horrible for daily driving. Now off roading in the sand or something like that is a different story. I ran mine in sand last weekend and I made it through, but it was boggin down like all hell. Needed more power....

Back on topic. I would suggest stepping up at least 2 gear sizes to make it even worthwhile. going from a 3.73 to a 4.10 just doesnt make sense with the amount of money you will spend. Go to at least 4.56. If that is too much gear for you, then stay at 3.73 because it wont make hardly a difference stepping up to 4.10. \

Oh and about the one inch tire difference between the 31's and 32's, its bigger than you think. I noticed a huge loss in performance when I went from 31's to 32's.
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Unread 05-08-2009, 10:24 AM   #8
SnowLeopard
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Everyone keeps saying you won't notice the difference from 3.73 to 4.11, but they say there's a big difference between 3.55 and 3.73. Since I'm only planning on going to 31" tires, if I did regear, I wouldn't want to go up to 4.56. If it gets you at 2500rpm at 70mph, with OD on, when you have OD go off in the mountains you'd be at like 3500-4000. That's also with 32's. If I'm only going to 31's, it'd be even worse. 4000rpm or more in the mountains..right now it's around 3-3500 on average. I think that stepping up to 4.11 would be enough to keep things in line with the tire size increase. Just thinking.
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Unread 05-08-2009, 11:33 AM   #9
98zjdave
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Quote:
Originally Posted by SnowLeopard View Post
Everyone keeps saying you won't notice the difference from 3.73 to 4.11, but they say there's a big difference between 3.55 and 3.73. Since I'm only planning on going to 31" tires, if I did regear, I wouldn't want to go up to 4.56. If it gets you at 2500rpm at 70mph, with OD on, when you have OD go off in the mountains you'd be at like 3500-4000. That's also with 32's. If I'm only going to 31's, it'd be even worse. 4000rpm or more in the mountains..right now it's around 3-3500 on average. I think that stepping up to 4.11 would be enough to keep things in line with the tire size increase. Just thinking.
Coming from someone that has swapped gears in plenty of things, it just wouldnt be worth going from 3.73 to 4.11. Yes you will be able to tell a difference in rpm, and a SLIGHT difference on the performance side, but not enough to justify how much you will spend to do it. No way would I ever swap my 3.55's for 3.73's, or my 3.31's for 3.55's.
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Unread 05-08-2009, 01:41 PM   #10
SnowLeopard
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But wouldn't 4.56 be overkill? I'm thinking long term here. As in after a lift and new tires, down the line of upgrades. I want to have true-tracs installed at some point, and I figured I might as well regear if they're already going to all that trouble. Just wonder how much the true-trac install would be on its own. What kind of difference would the 4.56 make with the I6 and 31" tires? Mileage, acceleration, rpm's?
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Unread 05-08-2009, 02:28 PM   #11
98zjdave
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Quote:
Originally Posted by SnowLeopard View Post
But wouldn't 4.56 be overkill? I'm thinking long term here. As in after a lift and new tires, down the line of upgrades. I want to have true-tracs installed at some point, and I figured I might as well regear if they're already going to all that trouble. Just wonder how much the true-trac install would be on its own. What kind of difference would the 4.56 make with the I6 and 31" tires? Mileage, acceleration, rpm's?
I recommned he stay with the 3.73's if he keeps the 31's, and regear if he goes with 32's or bigger. And If he is going to regear, just go with the 4.56's. Yes it might be a tad bit high rpm sometimes, but you have to figure if hes running 3.73's now with small 27-28" tires, and he increases the tire size by say 3-4 inches to 32's, its actually going to make his stock 3.73's behave as if they were, oh say 3.55's. So stepping up to a 4.56 with the new tire size would be like running the stock tires with say 4.10's. It wont be as bad as you think it would. Im running 32's with 3.55's and at 80mph im doing like 1800rpms haha its ridiculous. I need to regear myself and would love to regear to 4.56.

Add on... basically what I would recommend is 3.73-4.10's with 31's. Or with 32+ tires I would go with 4.56. Yes mileage will suffer with lower gears, but performance will be much better. Also, if you have a v8, you can get away with higher gearing unlike us sorry guys with the I-6 engine.
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