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Old 05-15-2007, 05:20 PM   #1
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Questions on axle ratio and Throttle body

Have a 99 TJ with a 4 banger. Need to put a 2" BB lift with probably OME shocks. Looking for more tq. Has the stock 3.07 ratio in the rear. Would like to add a TB from a 4.0 with the 1" spacer. What year TB from the 4.0L should I get?

What axle ratio should I be running with 31-32" tires?

Will do some 3-5 rated trails in the area. Won't be doing any thing more than 5's. Budget won't allow that for now, neither will my other half who is scared of heights/exposure. We live up at 5K in Colorado. Trails with alot of exposure, just won't work for her. So we'll do the milder stuff. Just good to get out with the family......

Dirk will be getting the suspension $, who has the TB's? And who has good pricing on the ring and pinion?

What should I expect to pay a shop to put in the ring and pinion?

I can do the shocks, TB, etc myself easily.

Just rebuilt the motor in my Harley, so the minor stuff, I'm good to go....


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Old 05-15-2007, 05:38 PM   #2
Knows a couple things...

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With the 2.5L engine, it wouldn't (shouldn't) have the 3.07, it should be 4.11. That can be verified by finding the ratio that is embossed into the steel tag between two bolts at the 9 o'clock position of your differential cover.

Regarding the TB, I'm in agreement with Jp magazine that you won't notice a difference running the 4.0L TB on your 2.5L. They tried it recently and didn't notice a thing.

With your 4.11 gearing, the only worthwhile gearing to go to is 4.88 but that would be a pretty low ratio for only 31" tires. Personally, I wouldn't regear for 31" tires, it's expensive and it's too easy to go too low (of a ratio) with a tire that small.

If you were going to 33" tires I'd strongly recommend that 4.88 ratio. If you did have lower gearing installed, it's typically pretty close to $1200 total for both axles including all parts and labor.

When you have a choice, buy American.

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Old 05-15-2007, 06:18 PM   #3
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Yup, 4:11's just like you said, thanks!

Is there any performance mods you would reccomend?
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Old 05-15-2007, 06:23 PM   #4
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exhaust like a flowmaster 40 or 50 Little more power.
99 sahara
flowmaster40,hpd30 with aussie locker,currie upper joints,4.88's, lca skids,chromo shafts,vanco brakes,d35 with super 35 and arb locker,re 4.5" springs,currie arms,re front uppers,Re shocks in back,walkerevens shocks up front, Re track bars with currie jj joints,anti rock,ss brake lines,re rear sway bar links,jks 1.25" bl and mml,bfg 35x12.5 km2's,craiger soft 8's,ome steering stabilizer,currie hd steering,rockmen front bumper,emp tank skid,lots more too.
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Old 05-15-2007, 06:41 PM   #5
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Originally Posted by Demodave View Post
Is there any performance mods you would reccomend?
There are several combinations of things that you can do to a 4cyl that will give you minimal gains under the hood. However all of these combined will be way more expensive than just re-gearing the axles.
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Old 05-15-2007, 08:01 PM   #6
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but we already said he doesnt need to regear.

So i would just go with exhaust and if you still have jeep money left over, then go for something else, like a locker
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Old 05-17-2007, 09:21 AM   #7
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i don't think exhaust gives any more power.

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