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Unread 07-29-2009, 06:01 PM   #1
abe51
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Rear end swap

Can anyone tell me how can I find out what cars can I get a rear end out of to swap out.I love my jeep but want to get better gas millage. Only use it to go bach and forth to word and dont need a Dand 35 in it. I have a 2000 Jeep Grand Cherokee, 6 cyl auto ,run great buy rear end makeing noise now.I was think if I have to change it out why not try to get better gas mil too. Hope someone can help me.

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Unread 07-29-2009, 06:10 PM   #2
blackjack12982
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Aside from the grammatical and spelling errors, you want to swap your rear axle to get better gas mileage? Buy a Prius if you want better gas mileage. What do you mean you don't need a Dana 35 in it?
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Unread 07-29-2009, 07:56 PM   #3
abe51
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Thank You for your Insults. My X wife was pretty Good at that too. You must be someones X also or will be in the future. As far as your Prius comment,just because I own a Jeep doesn't mean I have to take it out in the wood or climb hills. I have owned this car for 10 yr. now and still don't fell so macho I have to insult others to feel good. Have a blessed day.
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Unread 07-29-2009, 08:06 PM   #4
blackjack12982
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No, not insults just facts. I'm not saying you own a Prius or you must wheel your Jeep. I'm just saying that you aren't going to get great mileage in a Jeep. It's not going to happen, I own a Liberty as well (as non-Jeep as it is), it still sucks at MPG's. Stop being childish and let us help you.

At no point in your response did you clarify what rearend you will swap in to get better gas mileage. The D35 rear you have is the lowest rung to get, you only go up from there. If you wish to have a direct swap, you're going to need to get a WJ rear to swap 99-04. Those will be direct swap-in's. The only way to get better gas mileage is to baby the skinny pedal, and don't drive in the city. You could change the gear ratio, but in doing so, you'll raise the RPM's needed to launch your vehicle and sucking down more gas. Swap in a new rear, upgrade the intake/exhaust, ensure that your catalytic converter isn't plugged, and all O2 sensors are good, and your MPG's should raise a bit.

BTW-You have a WJ, not an FSJ Cherokee
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Unread 07-29-2009, 08:31 PM   #5
sandman
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wow. abe51, calm down. everything blackjack said and asked made complete sense. what do you mean you dont need the d35? swapping an axle wont give you any better gas mileage, so he suggested buying a more gas friendly car, a prius. and your grammar is bad, next time you should re-read your post before you submit it because its hard to completly understand what your asking.

this is just a guess because this thread is full of fail but if your talking about swapping gears this can slightly help if your running big tires.
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Unread 07-29-2009, 09:07 PM   #6
abe51
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Thank you, That's the answer I wanted the first time. Please over look my typing. I don't type much and was going in a hurry, my wife wanted to use the computer. I was told I have a dana 35 in my jeep and was thinking of changing the gears to help with gas. I did make a call to the dealer and he told me I could but did not tell me what axle I could use.I thought someone here could help.In the old days we change the gears in our axle to get more power.I thought I might be able to do the other way around.
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Unread 07-29-2009, 09:13 PM   #7
gatorayde
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Lower gears = worse MPG

If you want a car with good MPG, consider taking the cash for clunkers offer.
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Unread 07-30-2009, 06:34 PM   #8
abe51
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Cash for clunkers offers up to $4,500 for old gas guzzler. That would be the trade in value.I wouldn't take that for my car,would you. Lower Gears= better excelleration,lower top end,bad gas millage. Taller Gears=slower excelleration, Higher top end,better gas millage. Look this wasn't that hard of a question.But has become a lot of trouble to get a straight answer. I'll check with my local Pul-a-Part, they are usually good on answering questions like this. Thank you for your support
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Unread 07-30-2009, 07:57 PM   #9
JrMechanic
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Quote:
Originally Posted by abe51 View Post
Cash for clunkers offers up to $4,500 for old gas guzzler. That would be the trade in value.I wouldn't take that for my car,would you. Lower Gears= better excelleration,lower top end,bad gas millage. Taller Gears=slower excelleration, Higher top end,better gas millage. Look this wasn't that hard of a question.But has become a lot of trouble to get a straight answer. I'll check with my local Pul-a-Part, they are usually good on answering questions like this. Thank you for your support
There's a medium there on both sides. Just installing a numerically lower gear set wont necessarily net you better mileage. The higher the gear ratio, the harder it is for the engine to turn the wheels resulting in more fuel consumption per matched RPM. Some I6 owners report that a lower gear ratio, such as 3:55's to 4:10's offers an increase in fuel mileage. Even though the engine is turning at a higher RPM, less load is being inflicted on it.

Now, you can pass that medium ground. Installing too high of a gear ratio results in the engine speed being increased too much, which over comes the advantage of less load on the engine and uses more fuel.

Being that you have a 4.0, you most likely have the 3:55 gears, unless you have the tow package in which case you should have 3:73's. Any lower than 3:55 you will lose any performance that you might have and believe it or not you WILL suck up more gas accelerating. Any higher than 3:73's on a bone stock 4.0 and you will gain performance, but cruising mileage will slowly dwindle away.

Basically, the Dana 35 with 3:55 gears (what you have stock) is most likely the best choice for you.
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Unread 07-30-2009, 09:00 PM   #10
abe51
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Thank You, If I do have to replace the axle I will stay with the stock axle for replacement.
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Unread 07-31-2009, 09:22 AM   #11
Mikeg175
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The gearing helping your mileage also reflects on your driving styles and road conditions . If you live in a nice flat area with lots of highway miles and very little stop and go then the 3.55's aren't bad . If you live in area with alot of hills and/or stop and go , then the higher 3.73 will be better for you . The major problem with this swap is , if your Jeep has 3.55's in the rear , then you will need to regear front if you change rear ratio . At that point , I am not sure how long it would take to recoup the cash outlay for the axle and gear swapping . I'd say check Car-parts.com and find a nice stock rear , that will bolt right in and call it a day and get another 10 years out of it .
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Unread 07-31-2009, 11:26 PM   #12
RedlegWJ
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The gist of it is, the Dana 35 is as small as you want to go. It's fine for what it is, but it isn't a good choice for the guys that enhance their performance with tire size and horsepower. The vehicle gets fairly decent mileage with the 4.0 and 3.55's for an SUV when you keep your foot out of it. The WJ 4.0 breaths a little better so you can get a little power out of it when you need it. If you DO have 3:73's, 3:55 will be better for mileage, but since you would have to swap the front too, that's gonna negate your savings for a couple years.
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Unread 07-31-2009, 11:34 PM   #13
GraKee99
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The cost of regearing alone isn't worth it. You won't make back what you spent to do it.
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Unread 08-01-2009, 02:48 PM   #14
abe51
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Thanks for your input.Luckily my car is only rear wheel drive.The dealer told me my biggest problem would be my on board computer.Also I have been running a hydrogen cell on it for about 9 months now.It helps a lot with the gas.With it off I get 13 mpg in town,with it on I get 24. I was looking for a way to improve on that.If I have to replace the rear end anyway, I thought it wouldn't hurt to check. I do thank y'all for your help and support.
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Unread 08-01-2009, 07:57 PM   #15
StrokedWJ
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Your on board computer has absolutely nothing to do with your rear axle or gear ratio. Please elaborate on your hydrogen cell setup...

What kind of noise is your axle making that makes you think you need to swap it out?
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