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Old 08-10-2010, 05:59 AM   #1
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Re-Gearing a 2.5L

Well after doing some searching here on how to increase power in the enigne it seems that it best to keep it stock. It looks like i would have to get the car re-geared to get the best out of its power. The jeep is used mostly for offroading and driving on snow so I dont mid sacrificing some drivability on the road for increased performance off-road. How expensive is this likely to be to get done? I think the ratio I would need to get for the jeep with 34 inch tires is 5.13 for the best power output. Is this right or am I miles off? Ive no real idea about the gearing it wouldnt be my stong point. I appreciate the help.
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Old 08-10-2010, 07:12 AM   #2
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that's overkill in my opinion. 4.88's are fine.

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Old 08-10-2010, 10:22 AM   #3
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Thanks for that, where would one go to get this done? Is there parts you can buy on the net and get them fitted? Would this be what I would be looking at getting?

Also excuse my ignorance but do you need two of them front and back?
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Old 08-10-2010, 10:32 AM   #4
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Your axles can't be regeared to a ratio lower than 4.88 so 5.13 is not even doable. I would stick with 33" tires and 4.88 gearing which is as big of a tire as your 2.5L engine can handle without losing too much power.

Yes you need two sets of ring & pinion gears, one per axle. But don't buy them on your own with expectation to supply them to the installing shop. If you do and something goes wrong, the installer will blame the parts you provided him and not cover them in his warranty. And then the parts provider will blame the installer and not want to cover them either.

Have the shop provide EVERYTHING and then their warranty will cover anything that goes bad which does happen. One of my R&P jobs went bad 3 weeks after completion and the shop covered the whole thing without drama because they provided all the parts and labor.
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Old 08-10-2010, 10:38 AM   #5
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Thanks for that again appreciate the help. Might be a bit tough for the mechanic in Ireland to source the parts but we will see what we can do. 4.88 it is and we'll probably be going down to 33" tires as well.
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Old 08-10-2010, 11:00 AM   #6

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One other thing to consider, the rear dana 35 axle should be okay with 33 tires. However if you plan to add a locker to it.. chances are it will bust on you. You might want to look at either upgrading the whole rear axle or upgrading the shafts.

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