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Old 07-29-2010, 06:36 AM   #1
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Question on gear ratio for my YJ

I running stock 3:07 in my 92 YJ with 33s. My plan is to replace the rear end with a ford 8.8 with 4:10 gears a locker and then replace the front gears to 4:10. My question is how big of a difference will the 3:07 to 4:10 make? I'd love to move up to a 4:56 or 4:88 but can't see spending the $$ if the 4:10s will do the job. Any opinions?

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Old 07-29-2010, 10:14 AM   #2
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4.10 will put it back to a stock feeling. I ran 4.56 with 33's for a while. little better for going up hill.

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Old 07-29-2010, 05:58 PM   #3
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Well it depends on what tire size your jeep came with stock. There are a few different tire sizes that were available from the factory. Assuming your jeep came with 30" tires you will be considerably lower with 4.10 than the 3.07

Here is what the numbers look like based on a 30" tire size. As a constant we'll use 2000 rpms and 4th gear.

Stock setup is 3.07 gears on 30's which puts you at 58.1 mph.

With 3.07 gears and on the 33's your running now, your at 63.9 mph and with the 4.10 gears you'll be dropping to 47.9 mph. That is about 10 mph difference from stock.

The closest to stock on 33's would be 3.50 gears which would get you to 56.1 mph.


Now I'm not saying put 3.50 gears in Jeep because you also have to take into consideration the extra mass your turning. If your wanting near stock I would go with 3.73 gears.

It really boils down to what function your Jeep serves. If it is a daily driver and goes out on the trail once in a great while I would go with 3.73 or stay with the 4.10's that come with the 8.8. If you do a lot of wheeling and don't get out on the highway much I would go 4.56 or 4.88 gears. Cost is another issue you need to consider. Since you're asking the question I have to assume that you won't be doing the work yourself since this isn't your average DIY job. It normally costs between $600-$1000 per axle to get your gears changed. Most shops that I've talked to lean more towards $800 and up. So if cost is an issue I would go 4.10 gears.

Just my 2 cents.
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Old 07-29-2010, 06:29 PM   #4
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Your best bet is 410 Eps if it's a every day driver. 456 is great for off road it just sucks slot of gas if you use it every day
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Old 07-29-2010, 09:11 PM   #5
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I'd go 4:10s. Why change to axles? It's expensive enough to do one. I went from 3:07 to 4:10s & like it. A HUGE difference in power. I wouldn't go any deeper.
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Old 07-29-2010, 09:12 PM   #6
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great info. Thanks. My original plan was to use the limited slip differential that comes in some of the later 8.8 rear ends. But I'd prefer and actual locker b/c I've heard some not so great reviews of ford's LSD. To throw a monkey wrench in my plans I had a ford machanic tell me today that the 8.8 is a piece of crap. So, I've got 2 more questions for you guys.

Should I scrap the 8.8 and look for a dana 44? (seems like in the end that's gonna cost more)

How do you guys feel about the Aussie lockers? Seems like a good bang for the buck. I like to ride wooded trails, mud and play around on some small rocks. I'm not looking to build a rock crawler or anything.

Thanks for the advice
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Old 07-29-2010, 09:16 PM   #7
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Quote:
Originally Posted by Mikedavis33 View Post
great info. Thanks. My original plan was to use the limited slip differential that comes in some of the later 8.8 rear ends. But I'd prefer and actual locker b/c I've heard some not so great reviews of ford's LSD. To throw a monkey wrench in my plans I had a ford machanic tell me today that the 8.8 is a piece of crap. So, I've got 2 more questions for you guys.

Should I scrap the 8.8 and look for a dana 44? (seems like in the end that's gonna cost more)

How do you guys feel about the Aussie lockers? Seems like a good bang for the buck. I like to ride wooded trails, mud and play around on some small rocks. I'm not looking to build a rock crawler or anything.

Thanks for the advice
Did you backhand him and walk out?!?! Loads of Jeepers are running them. He doesn't know what he's talking about.

I never had any issues with my 8.8 and it was on 35's and behind a moderately built Chevy 355.

I don't know about the Aussie lockers. I don't have any first hand experience with them.
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Old 07-30-2010, 11:52 AM   #8
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i like my 8.8 and its supposed to be strong enough for the LS1 im putting in (we'll see though)

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