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-   -   Gear ratio questions (http://www.wranglerforum.com/f210/gear-ratio-questions-49053.html)

Mattfochler 04-18-2010 12:32 PM

Gear ratio questions
 
Hey Guys,
Well the rear differential in my jeep decided to shit the bed on me the other day and it looks like we are gona throw some new new gears in it. I talked to a friend who has a good knowledge of mechanics and he says I should go with 3.50 or a 3.55 gear ratio. The jeep is a 97 with a 4.0 and 5 speed Hurst shifter. Ive got 33's on a 15 inch rim and was wondering if you guys could help me pick out the proper set of gears for this set up.

Thanks for the Help,
Matt

jdhallissey 04-18-2010 12:35 PM

Umm no- go with 4.56's or 4.88's. Your jeep will be all kind of pissed off at you driving on those gears. I run 5.13's in my jeep FYI on 33's.

Mattfochler 04-18-2010 12:42 PM

Ok, how is the gas millage going to be like with those? My jeep is my daily driver and it only goes off roading occasionally. I just need something that is going to be reliable but still has potential for light off roading.

Atthehop 04-18-2010 01:04 PM

Reminder - both axles must match

jdhallissey 04-18-2010 01:15 PM

Your driving a brick. Your gas mileage will be around 14 depending on how you drive-- IE lead foot etc etc

Ken Steele 04-18-2010 03:00 PM

I ran 4.56's on 33's for a few years. I would not recommend going any numerically higher with your ratio than that. 4.10's would probably be perfect, but if there is even a chance of bumping up to 35's later then 4.56 is a good choice.

KBR97 04-18-2010 03:13 PM

From what I have read on this forum...4.56 is ideal for 33's and 4.88 is ideal for 35s. That will regain any lost power, torque, performance or gas mileage.

And as Atthehop stated if you regear the rear differential you MUST also regear the front to match.

HyperBuzzin 04-18-2010 03:34 PM

Quote:

Originally Posted by Mattfochler (Post 601229)
I talked to a friend who has a good knowledge of mechanics and he says I should go with 3.50 or a 3.55 gear ratio.

Maybe he knows mechanics.... but not Jeeps or what axle ratios work with what tire size.
I'm running 3.73's w/32's and could stand to gear lower (higher number)

KBR97 04-18-2010 04:15 PM

BTW you say you have a 1997 4.0...chances are you already have 3.55 gearing. 97 was the only year that was offered and I think most 97 Wrangler "sports" came with that gearing. Check the tag on the diff cover and see what it says...there will be 3 numbers

Ken Steele 04-18-2010 05:02 PM

I don't know about most 97 Sports, but mine came factory with 3.07's. I put 33's on it in 2002 and it was a dog. I swapped in a Dana 44 w/ 3.73's and it was much better. I later regeared to 4.56 and it was just a tad too much gearing. I am now on 35's and the 4.56 gears seem to be the best fit for power and fuel economy-much better than it was on 33's with the same gears.

KBR97 04-18-2010 05:45 PM

Your right Ken...there was 2 options...3.07 or 3.55

Ken Steele 04-18-2010 11:29 PM

I have no idea why they ever made 3.07s. Those gears were horrible even with stock tire sizes.

jdhallissey 04-18-2010 11:41 PM

I had a buddy that has a 97 mustang v-6 that came from the factory with 2.73's hahahahaa

Kilroy 04-19-2010 06:16 AM

Quote:

Originally Posted by Ken Steele (Post 601832)
I have no idea why they ever made 3.07s. Those gears were horrible even with stock tire sizes.

...to meet federal fuel economy requirements.

Kilroy 04-19-2010 06:21 AM

4:10 is ok for those tires if most of your driving is on the flats. Else 4:56 to make it feel like a Jeep.


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