Gearing and RPM Question - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 03-13-2012, 07:28 AM   #1
NASCAR JEEP!!!!

WF Supporting Member
 
kj 92yj's Avatar
 
Join Date: Jun 2010
Location: The 'Nati. Go REDS
Posts: 470
Gearing and RPM Question

Morning All, just had 4.88's installed last week and i'm doing about 2600 / 2700 RPM's at 70 on the highway. I am assuming this is normal, but wanted to ask those who have already done this. Running 35's.

It's VERY strange to drive the Jeep at 2700 RPM's. Something I am definitely not used to, but have to say it hums right a long with no problem. Engine seems to not care at all. Temp gauge still the same and oil pressure is normal.

Thanks!

__________________

Yo Ho Yo Ho a Pirates Life For Me......
1992 Islander - I6 - 3" Body Lift; 2.5" RC Suspension Lift; Mystery Shackle Lift; 35x12.50x15 on 15x8's.
kj 92yj is offline   Quote Quick Reply
Old 03-13-2012, 07:46 AM   #2
Jeeper
 
aalmutawakil's Avatar
 
Join Date: Nov 2008
Location: VA
Posts: 240
LOOOOL i was about to asking something similar. I have 35's on now and when I am at 80 its reading 65. not good. how can I adjust that?

Dont mean to hi-jack your thread...

__________________

__________
l__l__\____\
l/-\l-_l_/ --#llllll#-
\__/ - \____H ___H MUTAWAKIL
(o)__) (o)__)---o-)__) 4847444222
aalmutawakil is offline   Quote Quick Reply
Old 03-13-2012, 07:51 AM   #3
NASCAR JEEP!!!!

WF Supporting Member
 
kj 92yj's Avatar
 
Join Date: Jun 2010
Location: The 'Nati. Go REDS
Posts: 470
you mean when you're doing 65 (measured with a gps or smart phone speedo) your actual jeep speedo says 80? that's a speedo gearing adjustment problem. not sure how to fix tha except to buy a new speedo gear and plug it into your x-fer case.

have you noticed your RPM gauge tho? Is my reading right?
__________________

Yo Ho Yo Ho a Pirates Life For Me......
1992 Islander - I6 - 3" Body Lift; 2.5" RC Suspension Lift; Mystery Shackle Lift; 35x12.50x15 on 15x8's.
kj 92yj is offline   Quote Quick Reply
Old 03-13-2012, 07:59 AM   #4
Jeeper
 
aalmutawakil's Avatar
 
Join Date: Nov 2008
Location: VA
Posts: 240
RPM is fine. there is nothing wrong with it. But do you know what i actually need to get?
__________________

__________
l__l__\____\
l/-\l-_l_/ --#llllll#-
\__/ - \____H ___H MUTAWAKIL
(o)__) (o)__)---o-)__) 4847444222
aalmutawakil is offline   Quote Quick Reply
Old 03-13-2012, 08:04 AM   #5
Jeeper
 
wwch99tj's Avatar
 
Join Date: Mar 2011
Location: Felton Delaware
Posts: 4,828
Quote:
Originally Posted by aalmutawakil
RPM is fine. there is nothing wrong with it. But do you know what i actually need to get?
You need a new speedo gear with a different tooth count....
You need to know your tire size your gear ratio
http://www.raingler.com/tech/speedoChart.asp
Quadratec has the gears for $40
wwch99tj is online now   Quote Quick Reply
Old 03-13-2012, 08:06 AM   #6
NASCAR JEEP!!!!

WF Supporting Member
 
kj 92yj's Avatar
 
Join Date: Jun 2010
Location: The 'Nati. Go REDS
Posts: 470
here's the quadratec link:

Search Results - Quadratec
__________________

Yo Ho Yo Ho a Pirates Life For Me......
1992 Islander - I6 - 3" Body Lift; 2.5" RC Suspension Lift; Mystery Shackle Lift; 35x12.50x15 on 15x8's.
kj 92yj is offline   Quote Quick Reply
Old 03-13-2012, 08:09 AM   #7
Jeeper
 
aalmutawakil's Avatar
 
Join Date: Nov 2008
Location: VA
Posts: 240
thats my question on the other thread. how do i know my rear end and gear ratio?
__________________

__________
l__l__\____\
l/-\l-_l_/ --#llllll#-
\__/ - \____H ___H MUTAWAKIL
(o)__) (o)__)---o-)__) 4847444222
aalmutawakil is offline   Quote Quick Reply
Old 03-13-2012, 08:11 AM   #8
Jeeper
 
wwch99tj's Avatar
 
Join Date: Mar 2011
Location: Felton Delaware
Posts: 4,828

And there should be a tag at the 9 o'clock position with numbers stamped on it
You can see on what would be the bottom left corner of the tag I have 4:11's
wwch99tj is online now   Quote Quick Reply
Old 03-13-2012, 08:16 AM   #9
NASCAR JEEP!!!!

WF Supporting Member
 
kj 92yj's Avatar
 
Join Date: Jun 2010
Location: The 'Nati. Go REDS
Posts: 470
you'll have to crack open the case and look at your actual ring and pinioin to know the ratio. there are charts you can look up on quadratec that can give you an estimation based on tire size and RPM, but you're better off taking the cover off and trying to locate the stamping on the ring/pinion of the actual ratio.
__________________

Yo Ho Yo Ho a Pirates Life For Me......
1992 Islander - I6 - 3" Body Lift; 2.5" RC Suspension Lift; Mystery Shackle Lift; 35x12.50x15 on 15x8's.
kj 92yj is offline   Quote Quick Reply
Old 03-13-2012, 08:19 AM   #10
Jeeper
 
aalmutawakil's Avatar
 
Join Date: Nov 2008
Location: VA
Posts: 240
So I wouldnt need to crack it open?

Quote:
Originally Posted by wwch99tj View Post

And there should be a tag at the 9 o'clock position with numbers stamped on it
You can see on what would be the bottom left corner of the tag I have 4:11's
__________________

__________
l__l__\____\
l/-\l-_l_/ --#llllll#-
\__/ - \____H ___H MUTAWAKIL
(o)__) (o)__)---o-)__) 4847444222
aalmutawakil is offline   Quote Quick Reply
Old 03-13-2012, 08:21 AM   #11
Jeeper
 
wwch99tj's Avatar
 
Join Date: Mar 2011
Location: Felton Delaware
Posts: 4,828
Not if you have the tag still on the cover
wwch99tj is online now   Quote Quick Reply
Old 03-13-2012, 08:22 AM   #12
NASCAR JEEP!!!!

WF Supporting Member
 
kj 92yj's Avatar
 
Join Date: Jun 2010
Location: The 'Nati. Go REDS
Posts: 470
well, i can't see that, but I'll assume it's there. i think it's the glare......and, in my opinion, yes you'll need to crack it open and look because whatever is stamped on your cover certainly is NOT what's inside. that can be determined due to the fact that your speedometer is not accurrate...
__________________

Yo Ho Yo Ho a Pirates Life For Me......
1992 Islander - I6 - 3" Body Lift; 2.5" RC Suspension Lift; Mystery Shackle Lift; 35x12.50x15 on 15x8's.
kj 92yj is offline   Quote Quick Reply
Old 03-13-2012, 08:31 AM   #13
Jeeper
 
wwch99tj's Avatar
 
Join Date: Mar 2011
Location: Felton Delaware
Posts: 4,828
Quote:
Originally Posted by aalmutawakil
So I wouldnt need to crack it open?
If im reading your jeep profile right you have a 2.5 4cyl. They came stock with 4:11's and with you having 35's instead of the stock 28's, that would cause your speedometer to be of greatly
wwch99tj is online now   Quote Quick Reply
Old 03-13-2012, 08:36 AM   #14
NASCAR JEEP!!!!

WF Supporting Member
 
kj 92yj's Avatar
 
Join Date: Jun 2010
Location: The 'Nati. Go REDS
Posts: 470
ahh, good point. i didn't go in and view his profile. yes, that would make a huge difference......but i'm surprised he's able to go 80 on 35's with 4.11's in a 2.5L.

hell, i couldn't get anywhere near 80 on 35's with an I6.

just me??
__________________

Yo Ho Yo Ho a Pirates Life For Me......
1992 Islander - I6 - 3" Body Lift; 2.5" RC Suspension Lift; Mystery Shackle Lift; 35x12.50x15 on 15x8's.
kj 92yj is offline   Quote Quick Reply
Old 03-13-2012, 08:42 AM   #15
Jeeper
 
aalmutawakil's Avatar
 
Join Date: Nov 2008
Location: VA
Posts: 240
I know my speedo is off cuz of my 35's thats why i wanted to be able to make it accurate

Quote:
Originally Posted by wwch99tj View Post
If im reading your jeep profile right you have a 2.5 4cyl. They came stock with 4:11's and with you having 35's instead of the stock 28's, that would cause your speedometer to be of greatly

__________________

__________
l__l__\____\
l/-\l-_l_/ --#llllll#-
\__/ - \____H ___H MUTAWAKIL
(o)__) (o)__)---o-)__) 4847444222
aalmutawakil 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:
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
JKU Hardtop Hoisting Question NFRs2000NYC JK General Discussion Forum 37 10-06-2014 11:18 AM
4:10s 3.8 and 35s wanderer JK General Discussion Forum 29 03-18-2012 12:04 AM
SYE and Adjustable Upper & Lower CA's bcpaddler TJ General Discussion Forum 28 03-13-2012 07:52 AM
Borla Header install 89 YJ 4.2L, gasket question and Idle issue bdr3355 YJ Tech Forum 1 03-13-2012 12:03 AM
8.8 Question yjJEEPyj YJ Tech Forum 1 03-12-2012 11:57 PM



Download our Mobile App

» Featured Product

All times are GMT -5. The time now is 06:27 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