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Discussion Starter · #1 ·
I have read bad things about 4.88 in the Dana 30, What is your Opt. I am Running 35's with no plans on any larger.

I am working on a 8.8 for the rear, And planning on a HP D30 front. I am Leaning more to 4.56 with the 35's because my jeep sees more road than trails, but more so because the problems I read about the pinion on the 4.88 being so small in the Dana 30, Is this true for the 4.88?

Also looking at the RPM's I feel like the 4.56 will have better street maners than the 4.88.

I have 4.0
35" tire no plan on bigger
Nv3550 5 speed
axles will be 8.8 and HP D30

4.56 or 4.88????
I have been searching for info on this.
 

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From what I have read, the NV3550 has a 0.73 overdrive which is getting close to the 0.69 that the auto overdrives have so with 35s, the 4.88s might still be the best choice. I put 4.88s in an LJ for a friend of mine about 2 years ago and it is fine. It's not so much the size of the pinion (it is smaller) but it only has 8 teeth on it. But, the 4.56s only have 9. The 4.88s on the LJ with 35s and the 4speed auto turned out to be the perfect combo for her. She lives in Florida but it restored the performance back to stock. Prior to the change, the OD was useless and even then, the performance and fuel mileage was still bad.

There are plenty of folks on here that can give you the pros and cons.
 

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Discussion Starter · #3 ·
From What I have read The NV3550 has a .78 5th Gear, making me want to lean to the 4.56 more.
 

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With a .78 OD, depending on how you drive, probably could go either way. Also with the TJ being lighter than an LJ, 4.56s might still be ok but again, a lot of it is how you drive and if you have heavy gear (bumpers, winch, spare, tools, etc.)

Running some quick numbers, at 60 mph you should be turning about 2080 rpm in 5th with the 35s and 4.56s and 2230 rpm in 5th with 4.88s. My rule of thumb for a light TJ with no larger than 33x10.50s is about 2100 at 60 for the sweet spot for the 4.0. For 33x12.50s and up, heavier gear, and LJs, you need to add a little more for each item in consideration. That being said, I think the 4.88s would still be the best choice but the 4.56s wouldn't be horrible.
 

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4.88 is fine in the D30, that's a very commonly installed ratio that I have run in two TJs. The rumor you heard about the 4.88 pinion gear being too small is 100% BS. I would run nothing but that ratio with 35's and 5-speed transmission, its highway RPMs are perfect.
 

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What you also have to factor in, is RPM's should be HIGHER at a given speed than stock because you are running heavier tires that require more to rotate them.
 

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2002 jeep wrangler x
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What would be the best set up for the infamous 42rle having the 2.4l engine if I wanna roll on 33" tires? Will it reach the freeway's speed?
 

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4.88 which should work very well with the 42RLE and 33" tires. Don't even consider a higher ratio like 4.56.
 

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4.88 which should work very well with the 42RLE and 33" tires. Don't even consider a higher ratio like 4.56.
Those jeeps carry the 4.56 gears stock. No kidding!! All the jeepers make the wtf face when I tell them that. :happyyes:
 

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2002 jeep wrangler x
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all tjs from 2003 to 2006 have the 4.56 gears when the 2.4 engine and the 42rle automatic transmission are present
 

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What Jerry said.


I recently swapped my 410 gears to 488s. I struggled with the same question as you 456 or 488? After conversing with Jerry I took his advice and installed 488 gears. I'm still running 33" tires with the intention of swapping to 35" tires soon. At 75mph I'm turning 3000 RPMs I have the same engine and running gear as you. When I upgrade to the 35" tires those RPMs should drop by about 250 RPMs.

The real benefit is my jeep performers much better getting up to highway speeds. I had 410 gears previously, even with stock tires the 410 gear was a dog compared to what I'm currently running. There is not a whole lot of difference between 456 or the 488. Your upgrading for performance I would recommend the 488s you won't be disappointed.
 

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mine came like that, i'm telling you that because, i wanted to do a suspension lift in order to install 33" tires. 1st thing i got asked what gears my tj has, i told them i didn't know. no need to say they told to me that it was necessary to check at the dealer for my built sheet. i was informed by people from the dealer about this.
 

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mine came like that, i'm telling you that because, i wanted to do a suspension lift in order to install 33" tires. 1st thing i got asked what gears my tj has, i told them i didn't know. no need to say they told to me that it was necessary to check at the dealer for my built sheet. i was informed by people from the dealer about this.
I see that it was an available option
 

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What scenario am i facing if i switch to 33 inches tires? being my daily driver i have my reserves with the 33" tires, because with my 31 tires i have problems reaching 75 miles per hour, and in many spots going uphill on the freeway drops down to 60 creating myself problems with other drivers yelling at me to move over.

33" tires should be combine with 4.88 gears?

i dont care on the mpg department, this is a jeep, i just dont wanna be short one with the jeepers.
 

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I'm running a 04 Rubicon with a 5 speed manual transmission, 488 gears and 33" tires. I just drove from Az to Mn six weeks ago. I could not be happier. My jeep has never performed so well.
 
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