Front pinion angle - measuring against the frame - JKowners.com : Jeep Wrangler JK Forum
 
LinkBack Thread Tools Display Modes
post #1 of 6 Old 08-25-2019, 12:08 PM Thread Starter
Granite Guru
 
rockystock's Avatar
 
Join Date: May 2014
Location: Knoxville, TN
Posts: 424
Garage
Feedback: 0 reviews
Front pinion angle - measuring against the frame

Screwing with my front pinion angle today. I'm using both a bubble level and a phone app (Clinometer, works well actually). With the app, I can "calibrate" or set the zero against any angled straight surface.

Questions for you all: how do you get your reference "zero" to measure the pinion angle? I know most just say "park on level floor" but I don't want to trust that the floor is level enough. I used the clinometer app to set zero to the frame rails (middle of jeep, under doors) and then measured the pinion. Second question: are the lower frame rails designed to be level to the ground?

Sent from my LG-H910 using Tapatalk
rockystock is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 08-25-2019, 05:30 PM
Rock God
 
ronjenx's Avatar
 
Join Date: Aug 2010
Location: Maine
Posts: 1,876
Feedback: 0 reviews

Pinion angle is the angle of the pinion axis compared to the drive shaft axis. Frame rails, floor level, don't matter.

2008 Unlimited Rubicon Automatic
ronjenx is offline  
post #3 of 6 Old 08-25-2019, 06:43 PM Thread Starter
Granite Guru
 
rockystock's Avatar
 
Join Date: May 2014
Location: Knoxville, TN
Posts: 424
Garage
Feedback: 0 reviews

Sorry, I should have added that I was also trying to adjust caster. I know that stock caster is 6 degrees, making the pinion angle zero at normal ride height.

Sent from my LG-H910 using Tapatalk
rockystock is offline  
Sponsored Links
Advertisement
 
post #4 of 6 Old 08-25-2019, 07:10 PM
Rock God
 
ronjenx's Avatar
 
Join Date: Aug 2010
Location: Maine
Posts: 1,876
Feedback: 0 reviews

I suspected that, but took your post at face value.

Stock caster for the 2008 JK is +4.2, 0.5, with max left/right difference 0.65.

Messing with caster at home is best done after you get the caster angle from an alignment machine. Then you can keep track of how many degrees you change it by putting an inclinometer on a flat surface on the axle. If you keep a record of the changes you make, the levelness of the frame and floor still won't matter.

The reason you should get the initial caster angle from an alignment shop is caster can't be directly measured. It is obtained from measuring how much the wheels tip when they are turned from side to side.

2008 Unlimited Rubicon Automatic

Last edited by ronjenx; 08-25-2019 at 07:25 PM.
ronjenx is offline  
post #5 of 6 Old 08-25-2019, 10:06 PM Thread Starter
Granite Guru
 
rockystock's Avatar
 
Join Date: May 2014
Location: Knoxville, TN
Posts: 424
Garage
Feedback: 0 reviews

Agreed - thanks. Yeah I'm just getting an initial caster to get it to the alignment shop.

Sent from my LG-H910 using Tapatalk
rockystock is offline  
post #6 of 6 Old 08-26-2019, 04:30 AM
Rock God
 
Chipewa's Avatar
 
Join Date: Jan 2012
Location: Farmington Hills MI
Posts: 1,184
Feedback: 0 reviews

Rough caster angle can be calculated by using an angle gauge on the flat on top of the steering knuckle and the flat on the pinion flange. See attached pic for concept.
Attached Images
 

LS3 2007 JKU X - Red Rock, 2012 JKU Rubicon - Deep Cherry Red, 2001 TJ - Black
Chipewa is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JKowners.com : Jeep Wrangler JK 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:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



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 On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome