new shackles - Page 2 -
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 > Models > Jeep Wrangler Forums > YJ Wrangler Technical Forum > new shackles

Nitro Gear Packages Now Available at Rockridge 4wdJEEP Gear Change Packages From ROCKRIDGE 4WD. We Are DIFFThe ULTIMATE "Selectable" Locker System! Brough

Unread 03-05-2013, 09:30 AM   #16
Patience, Grasshopper
JeeperDon's Avatar
1993 YJ Wrangler 
Join Date: Jan 2005
Location: Albuquerque, NM
Posts: 6,763
On another thread recently they were talking about caster angle and shackles. I did some more research and math after that. I found that less caster is needed with larger tires, since the tire/road contact point is further ahead of the knuckle swivel. The OEM spec for my YJ is 6.3 (+/-1), which turns out to be about 5 needed for a 35" tire (compared to a stock 29" tire).

Doing the caster math as it applies to shackles, changing the shackle length by 3/4" changes the caster angle by 1. So, lengthening a shackle from the stock 4" means lowering the caster, which means for twitchier on-road handling and poorer on-road return-to-center (Jeep seems to have a mind of it's own). My present shackles are 5.75" long, and my caster is about 3.5 (had it measured by a shop), and the Jeep indeed has a mind of it's own on-road.

Actually, today's garage project is to fab up a new pair of front shackles that are maybe 4.5" long to get my caster much closer to the 5 I figure is good. I think it's worth a couple hours of shop time and 2' of steel to experiment.

'93 YJ, '02 GM 4.3 Vortec V6, SOA, dual ARB's, 8.8+D30(w/WarnHubs), 4.88 gears, 35" BFG KM2's, AX15, 15x7 wheels, NP231+4:1+SYE+2LO, York OBA, Warn M8000, no top or doors Apr-Oct.
Member and Web guy: New Mexico 4 Wheelers My Truck Page on NM4W Site
JeeperDon is offline   Reply With Quote Quick reply to this message
Unread 03-05-2013, 10:11 AM   #17
Registered User
1991 YJ Wrangler 
Join Date: May 2011
Location: Tulsa, OK
Posts: 1,247
4.5"lg with 3/8" bolt holes?
I guess Im asking what size dia. are the bolts?
wondering of how much meat will be needed around the edges
Used to have a good sig but Mod threated to ban me...

[I]Errrrrrr[/I], Will complain else where - &y
Andywear is offline   Reply With Quote Quick reply to this message
Unread 03-05-2013, 10:32 AM   #18
Registered User
1991 YJ Wrangler 
Join Date: Dec 2012
Location: Marietta, GA
Posts: 520
Most heavy duty aftermarket are 3/8" x 2" steel with 1/2" bolt holes and a 1" end radius.
tom_sprecher is offline   Reply With Quote Quick reply to this message

Quick Reply

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
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:


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

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