Gear Ratio Causing Problems? - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Wrangler Forums > TJ Wrangler Technical Forum > Gear Ratio Causing Problems?

Engo LED Flush Mount Lights *PAIR* Flood or Spot 1,600 LumYukon Ultimate 35 axle kit for c/clip axles with Yukon ZipRockridge 4WD IS Taking Zone Offroad Suspension Lift Kits

Reply
Unread 04-19-2010, 02:44 AM   #1
RoyalCask
Registered User
2000 TJ Wrangler 
 
Join Date: May 2009
Location: FL
Posts: 6
Gear Ratio Causing Problems?

2000 Jeep Wrangler 4.0L I6, Auto.

I purchased a jeep for a steal about a month ago, and the previous owner had upgraded a lot of things on this jeep. Two of the many upgrades are 33" Tires, and a 4" lift. I have been getting terrible gas mileage, and have a hard time getting over 70MPH, god forbid I am on any incline. So, I slid under and took a gander at the gear ratio it had and it is 3.07. What gear ratio should I have with my Jeep, and these upgrades? Would the gear ratio be causing the very low MPG's, and trouble gaining speed?

Also, every so often my oil gauge will drop almost instantly from 80 to 0, and then slowly start going up, and then drop back to 0 again. After a little bit it will make it's way back to a steady 80. Any ideas?

Also, also, will I have any problems with this setup having the stock yoke and drive shaft?

My Jeep (Sorry for the bad pictures, will post better ones later.):





RoyalCask is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 08:12 AM   #2
mainliner
Registered User
1999 TJ Wrangler 
 
Join Date: Oct 2009
Location: Sarasota, FL
Posts: 21
Do you know of the speedometer gear has been changed? If it hasn't, then with 3.07 gears and 33s, your speedometer is going to be way off. I have the same setup and for me 70 mph on the speedo is actually 84mph. It's a near 5:6 ratio, 5 speedo/odometer miles for every 6 actual miles.
mainliner is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 08:15 AM   #3
slafferty
Registered User
2000 TJ Wrangler 
 
Join Date: Sep 2008
Location: Kimbolton, Ohio
Posts: 1,403
with 33's and an auto 4.10's.. I'd find the stock complete rearedns out a 4 cylinder, this would save you some money. if you plan on 35's 4.56. A sye and new shaft would be better but if you dont have any viberations with your current set up you may be fine,
__________________
'00 TJ, 4.0, nv3550 spd, E-lockers Front and Rear, 4.88 gears. Homebuilt Bumpers/ tube doors.. Homebuilt Long Arm in the making... 35 inch MT-R's ordered[QUOTE=RUBtjICON;9622056]If you arent scratching it, you arent trying hard enough :tea:[/QUOTE]

[U][I][B]MY BUILD THREAD[/B][/I][/U]
[URL="http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html"][COLOR="RoyalBlue"][SIZE="4"]http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html[/SIZE][/COLOR][/URL]
slafferty is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 08:16 AM   #4
slafferty
Registered User
2000 TJ Wrangler 
 
Join Date: Sep 2008
Location: Kimbolton, Ohio
Posts: 1,403
and yes an undergeared jeep will hurt power and milage, but its never going to be great
__________________
'00 TJ, 4.0, nv3550 spd, E-lockers Front and Rear, 4.88 gears. Homebuilt Bumpers/ tube doors.. Homebuilt Long Arm in the making... 35 inch MT-R's ordered[QUOTE=RUBtjICON;9622056]If you arent scratching it, you arent trying hard enough :tea:[/QUOTE]

[U][I][B]MY BUILD THREAD[/B][/I][/U]
[URL="http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html"][COLOR="RoyalBlue"][SIZE="4"]http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html[/SIZE][/COLOR][/URL]
slafferty is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 08:18 AM   #5
2GPS4ME
Senior Member
 
2GPS4ME's Avatar
1998 TJ Wrangler 
 
Join Date: Jan 2008
Location: 44.1N, 103.2W
Posts: 849
Look at the factory info sticker near the hinges on the driver's door. My factory tire size was 205/75-15, which translates into about 27.5" diameter tires with 3.07s. That explains why I couldn't go faster than about 73mph on a flat highway, even with the 4.0 & 5-speed.
__________________

WJ (WIFE JEEP) PROJECT COMING SOON
2GPS4ME is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 08:46 AM   #6
Jay12
Registered User
1997 TJ Wrangler 
 
Join Date: Aug 2008
Location: Gainesville, VA
Posts: 2,180
welcome to jeepforum. please fill out your profile so we can see your jeep's specs in the future. and yes if you regear your jeep will get its power and mpg back. About the driveshaft..do you have vibes? On 4" of lift you would have vibes without a change from slip yoke to the slip yoke emilinator. maybe the PO dropped the tcase?
Jay12 is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 10:17 AM   #7
slafferty
Registered User
2000 TJ Wrangler 
 
Join Date: Sep 2008
Location: Kimbolton, Ohio
Posts: 1,403
please fill in your profile, I figured he has a d30/35 combo since he said 3.07 gears, he stated he has a 4.0 and an auto which should be the 32rh 3 speed
__________________
'00 TJ, 4.0, nv3550 spd, E-lockers Front and Rear, 4.88 gears. Homebuilt Bumpers/ tube doors.. Homebuilt Long Arm in the making... 35 inch MT-R's ordered[QUOTE=RUBtjICON;9622056]If you arent scratching it, you arent trying hard enough :tea:[/QUOTE]

[U][I][B]MY BUILD THREAD[/B][/I][/U]
[URL="http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html"][COLOR="RoyalBlue"][SIZE="4"]http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html[/SIZE][/COLOR][/URL]
slafferty is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 11:18 AM   #8
RoyalCask
Registered User
2000 TJ Wrangler 
 
Join Date: May 2009
Location: FL
Posts: 6
Sorry guys, I got my profile updated. I do have the 3-speed auto.
RoyalCask is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 11:43 AM   #9
RoyalCask
Registered User
2000 TJ Wrangler 
 
Join Date: May 2009
Location: FL
Posts: 6
I have small, and I mean hardly noticeable vibs right on take off, but that's it.

As for the ratio, is it easier to buy a kit and have it installed, or buy new axle assemblies with 4.10 ratio? I found this listing for a D35/30 set with 4.10, but to be honest I have no idea if these would work with my Jeep:

ksl.com - Classifieds for Utah, Idaho, and Wyoming

If so, $200 OBO is a nice price.
RoyalCask is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 11:54 AM   #10
LJameson
Registered User
1990 YJ Wrangler 
 
Join Date: Jun 2008
Location: Elizabeth Lake, CA
Posts: 3,764
You can make them work, but it's not worth the effort. Those came off a YJ and have different brackets on them. What you would do is cut them off and weld on the TJ brackets, but again it's not worth it for a d35
__________________
"Anything to do with the land, I love."
"So it's probably eighty percent luck and twenty percent skill."

-Chris LeDoux

I never could figure what the sky was thinking, but the soil, she don't keep too many secrets.
LJameson is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 02:45 PM   #11
RoyalCask
Registered User
2000 TJ Wrangler 
 
Join Date: May 2009
Location: FL
Posts: 6
So my best bet is to find a pair that came off of a TJ? I am also thinking of holding out until I find some 44s. Would they be worth the wait, and would I be okay running my Jeep how it is until some come up?
RoyalCask is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 03:14 PM   #12
slafferty
Registered User
2000 TJ Wrangler 
 
Join Date: Sep 2008
Location: Kimbolton, Ohio
Posts: 1,403
depends on your wheelng style, If you plan to stay with 33's and not to hardcore trails you'll be better off finding a 30/35 combo with 4.10's if you wanna lock the front and rear and run 35's you'll at least want to swap with d35 with d44
__________________
'00 TJ, 4.0, nv3550 spd, E-lockers Front and Rear, 4.88 gears. Homebuilt Bumpers/ tube doors.. Homebuilt Long Arm in the making... 35 inch MT-R's ordered[QUOTE=RUBtjICON;9622056]If you arent scratching it, you arent trying hard enough :tea:[/QUOTE]

[U][I][B]MY BUILD THREAD[/B][/I][/U]
[URL="http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html"][COLOR="RoyalBlue"][SIZE="4"]http://www.jeepforum.com/forum/f22/slaffertys-2000-tj-build-1121555/index2.html[/SIZE][/COLOR][/URL]
slafferty is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 03:18 PM   #13
RoyalCask
Registered User
2000 TJ Wrangler 
 
Join Date: May 2009
Location: FL
Posts: 6
This Jeep is my dd, and it sees 95% pavement, and maybe 5% off-road action. So I am guessing stick with 30/35's. Now is it easier to just swap the ring and pinions, or the whole axle assembly. Note, I haven't ever attempted to swap ring and pinions, so this would be a first. I know a shop will probably charge an arm and a leg, is this something that a average Joe with some auto knowledge would be able to do without making things worse?

By the way, thank you everyone whose put input so far!
RoyalCask is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 03:22 PM   #14
RoyalCask
Registered User
2000 TJ Wrangler 
 
Join Date: May 2009
Location: FL
Posts: 6
Also, I would like to note I can get a hold of ring and pinions (4.10) for both the front and rear 30/35's for $50.00 total locally, if that plays any into having just the ring and pinion swapped. (Is that all that is needed to switch gear ratios, the ring and pinions?)
RoyalCask is offline   Reply With Quote Quick reply to this message
Unread 04-19-2010, 04:01 PM   #15
asknight
Registered User
2006 TJ Wrangler 
 
Join Date: Jul 2008
Location: Southwest, Arkansas
Posts: 2,189
Quote:
Originally Posted by RoyalCask View Post
Also, I would like to note I can get a hold of ring and pinions (4.10) for both the front and rear 30/35's for $50.00 total locally, if that plays any into having just the ring and pinion swapped. (Is that all that is needed to switch gear ratios, the ring and pinions?)
It's also a good idea to get a master overhaul kit for each diff @ about $100 each, as well. This includes all fresh bearings, setup shims, etc.
asknight is offline   Reply With Quote Quick reply to this message
Reply

Tags
gas mileage , gear ratio , low top speed , oil pressure

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
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


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.