Re-Gearing a 2.5L - Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today

Thread Tools

Please support our sponsors and let them know you heard about them on
Old 08-10-2010, 06:59 AM   #1
Join Date: Aug 2010
Location: Dublin, Ireland
Posts: 12
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.

jack01986 is offline   Quote
Old 08-10-2010, 08:12 AM   #2
RSC17's Avatar
Join Date: Nov 2009
Location: Cleveland, OH
Posts: 698
that's overkill in my opinion. 4.88's are fine.

Northeast Ohio 4x4 . com
4x4 Tech Discussion - Events - Classifieds

^Check us out
RSC17 is offline   Quote
Old 08-10-2010, 11:22 AM   #3
Join Date: Aug 2010
Location: Dublin, Ireland
Posts: 12
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?
jack01986 is offline   Quote
Old 08-10-2010, 11:32 AM   #4
Knows a couple things...

WF Supporting Member
Jerry Bransford's Avatar
Join Date: Nov 2005
Location: Escondido, Calif.
Posts: 38,474
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.
When you have a choice, buy American.

Jerry Bransford is offline   Quote
Old 08-10-2010, 11:38 AM   #5
Join Date: Aug 2010
Location: Dublin, Ireland
Posts: 12
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.
jack01986 is offline   Quote
Old 08-10-2010, 12:00 PM   #6

WF Supporting Member
::WF Administrator::
4Jeepn's Avatar
Join Date: Apr 2005
Location: Florence, KY
Posts: 11,095
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.

4Jeepn is offline   Quote

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Getting every pony from 2.5L & 4.0L quicksand97 TJ General Discussion Forum 6 09-13-2010 10:03 AM
Axle & gearing (again) nu arty boy TJ Tech Forum 0 05-29-2010 07:47 AM
Can someone explain the gearing to me? Dirt Diver YJ Tech Forum 7 02-21-2010 04:49 PM
Gearing Suggestions? Vaultzz YJ General Discussion Forum 24 11-02-2009 03:53 PM
2.5L Block Swap? hobbystock8 YJ Tech Forum 0 11-27-2007 06:38 PM

Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 04:00 AM.

User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2015 DragonByte Technologies Ltd.

Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC. is not in any way associated with the Chrysler Motors LLC