2012 jk 6 speed with 4.88 gears??? - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > JK Jeep Wrangler Forum > JK General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 01-15-2013, 03:23 PM   #1
Jeeper
 
zx6r's Avatar
 
Join Date: Jan 2012
Location: central pennsylvania
Posts: 325
Images: 1
2012 jk 6 speed with 4.88 gears???

My local 4x4 shop only deals in yukon gears and yukon does not offer 4.56 gears that i "think" i would like. I am running 35/12.5/15 tires. My only other options are 4.88 and 5.13 . Are 4.88 gears too much for a jk that sees most of its miles on the roadways?

zx6r is offline   Quote Quick Reply
Old 01-15-2013, 03:46 PM   #2
Jeeper

WF Supporting Member
 
Elarson's Avatar
 
Join Date: Aug 2012
Location: Saginaw, MI
Posts: 583
Quote:
Originally Posted by zx6r
My local 4x4 shop only deals in yukon gears and yukon does not offer 4.56 gears that i "think" i would like. I am running 35/12.5/15 tires. My only other options are 4.88 and 5.13 . Are 4.88 gears too much for a jk that sees most of its miles on the roadways?
It depends on your objectives. With 4.88 and 35's your RPM will be higher than normal gearing and stock tires so your MPG will go down but it will feel much more aggressive and responsive from an acceleration standpoint. If you don't mind the reduced mileage its awesome. If thats an issue than stick with 4.56 or 4.10.

__________________
Eric

CLICK HERE FOR MY BUILD THREAD:
Elarson is offline   Quote Quick Reply
Old 01-15-2013, 06:23 PM   #3
Jeeper
 
Join Date: Nov 2010
Posts: 248
4.88s will be about right with 37s, so if you plan on that down the road..go that route. If not, 4.56 would be better suited for 35s IMO. My 4.88s w/37s buzzes too high for me on the highway.
goodysgotacuda is offline   Quote Quick Reply
Old 01-16-2013, 07:24 AM   #4
Jeeper

WF Supporting Member
 
bo9roadking's Avatar
 
Join Date: Jul 2011
Location: San Antonio
Posts: 650
Quote:
Originally Posted by goodysgotacuda View Post
4.88s will be about right with 37s, so if you plan on that down the road..go that route. If not, 4.56 would be better suited for 35s IMO. My 4.88s w/37s buzzes too high for me on the highway.
Are you saying that your rpms are higher than you would like on the highway with 4.88 gears and 37" tires?

I agree that 4.88 is a good choice for a 37" tire and 4.56 would work for a 35" or a 37" tire. The 4.88 gear may be too much for 35" tires on a daily driver at least for a 2012+ with an auto transmission. On a 6 speed manual, your rpms will run about 100 rpm less than the auto in the top gear, so you have a little lower rpms.

I'm running 4.56 gears with 35" tires and at 70 mph, my rpms are slightly out of the green ECO marks on the tach. I think I'm running about 2600 rpm at 70 mph, but my 35" BFG KM2 tires are closer to 34". If I had a manual transmission, my highway rpms would be about 2500 with 4.56 gears. IMO, the 4.56 gears are almost too much for a 35" tire if you do a lot of highway driving.

I didn't have any problem with my 4.10 Rubicon gears with 35" tires, but because of adding extra weight on my JKU including significantly heavier axles and getting ready for 37" tires, I moved up to 4.56 gears. My rpms should drop back into the ECO area of the tach at about 2400 rpm when I do the tire swap.
__________________
2012 Unlimited Rubicon
Deep Cherry Red Crystal Pearl
bo9roadking is offline   Quote Quick Reply
Old 01-16-2013, 07:50 AM   #5
Jeeper
 
foo.c's Avatar
 
Join Date: Sep 2011
Posts: 284
Quote:
Originally Posted by Elarson View Post
It depends on your objectives. With 4.88 and 35's your RPM will be higher than normal gearing and stock tires so your MPG will go down but it will feel much more aggressive and responsive from an acceleration standpoint. If you don't mind the reduced mileage its awesome. If thats an issue than stick with 4.56 or 4.10.
I don't think 4.88's would be like you describe. Think more like a big rig where you shift almost immediately after getting going. It won't be quite that bad, but I would find it tiresome.

Personally I think 4.10's and 35's are almost perfect. I would only go lower if more of an offroad only rig, or you tow a lot.
__________________
2012 Black Forest Green JKU Rubicon
1998 Dark Slate Grand Cherokee 5.9 Limited
foo.c is offline   Quote Quick Reply
Old 01-16-2013, 05:09 PM   #6
Jeeper
 
Duke79's Avatar
 
Join Date: Sep 2012
Posts: 211
Images: 3
I have a '12 6 speed and just installed 4.88s. Like you said 4.88 are cheaper than 4.56. Northridge said they had to go through Mopar to get 4.56.

I find the 4.88 too low if your going to be doing anything over 60 mph for any length of time. They do rev quite a bit higher than the stock 3.21/32" combo.

I love it off road, highway they are really reving too high with a 35"tire. I was 3.21 with 35's and could only really use 5th gear on the flats and down hill....never see 6th. Now I am in 6th at 50 mph and at 65-70 its out of its "good mileage range".

I pull a camper so I wanted that extra power to get up the big hills here.

In my opinion 4.56 would be the "perfect gear". If you travel highway speeds alot stay away from 4.88.

I would say my mileage is a little worse overall with the 4.88 than the 3.21, but overall driving is much nicer.

__________________
'79 CJ7 304,'80 CJ7 360, '81 CJ8 304, '97 Sahara..All Gone
'10 Powerwheels, plastic wheels.
'12 JKU Sahara, 35"Duratracs, Spacer lift, 4.88s, Truetracs F/R. Flat Fenders
Duke79 is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may 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




» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 10:50 PM.



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