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Discussion Starter · #1 ·
So I have finally figured out why my jeep 2001 tj 2.5 sounds like ass and viberates like your moms.... teeth... anyways. I have a question for all??? how do I figure out what size this ring and pinion is? I haven't changed anything. But if theres a way to tell please let me know. Thanks.
 

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What size? The 2.5 will have a Dana 35 rear, which is a 7.6" ring gear, and the front is a Dana 30, which has a 7.2" ring gear.
 

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Are you asking for the gear ratio or actual size? The ratio will be written on a metal tag attached to the diffrrental cover bolt. 3.73, 4.11, 4.56 ect
 

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Jack up the rear. Put a mark on the tire and on the drive shaft. Turn the tire one revolution and count the turns on the ds. If it turns a tick over 3 times you have 3.07's and so on with the other ratios.
 

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Yes if your transmission is the 5-speed, your axle ratio is 4.10/4.11. Yes your f/r axle ratios are .01 different. :)
 

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Discussion Starter · #8 ·
SOOO what your telling me is that my rear end gear is going to be a 4.10 and not a 4.11? I just bought a 4.11 for my rear end today. I got told how to figure out the ratio is to divided by the amount of teeth on both gears. 37 divided by 9 was 4.11. that was what was in the rear end.
 

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He told you it would be 4.10 front and 4.11 rear, so you are fine.
 

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Discussion Starter · #10 ·
Sorry It was a long day and I saw f/r axle and I thought that meant front axle for some unknown reason. THANK GOD! After all this I know it sounds bad but reading all of these forums makes me want to throw a 4.88 in there just cause of my 35s. Any ideas? I know you guys are gonna say swap rear ends. Well that might happen but for right now thats a easy job. Thoughts?
 

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35" tires? Your rear axle isn't up to 35" tires... especially if you regeared to 4.88 which wouldn't be enough gear for that big of a size anyway due to your 2.5L engine. 33" is the biggest size I'll recommend for a stock Dana 35 rear axle.
 

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Such charts are EXTREMELY misleading because those charts don't take into account the transmission and engine type. Without correctly interpreting those numbers, the wrong axle ratio is too easily selected by the novice buyer. For example, the correct axle ratio will very greatly between the 32RH or 30RH 3-speed automatic, AX-15 or AX-5 5-speed, NSG370 6-speed, and 42RLE 4-speed automatic.

For example... let's take that you want to run the "right" ratio for 33" tires...
2.5L engine and 5-speed AX5 transmission: 4.88
2.5L and 3-speed automatic:4.56
4.0L and 42RLE: 4.88
4.0L and AX-15: 4.56
4.0L and 32RH 3-speed automatic: 4.10.
4.0L and NSG-370: 4.10

So just for 33" tires, you can see the right ratio can be 4.10, 4.56, or 4.88. :)
 

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I have 2.5 with 35s. I would say a 4.88 is a hell of a lot better than my 4.11 right now.
First, 35" tires are too big of a tire for your stock rear Dana 35 to be reliable with. Next, 4.88 isn't enough gear for the 2.5L and 35" tires. :)
 

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Discussion Starter · #18 ·
I planned on upgrading my rear and front end. I'm going to get introduced to a guy with muddy buddies out of ohio. So hopefully he can hook me up with some sort of set up. In my mind i'm just wanting to upgrade something that i'm going to have to replace anyways. funny thing is my ring and pinion just showed up and I ordered it last night.
 
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