AAL and shakles? Do i need shims?

[Hamr25]

Plan on building a bastard pack also have a 1.5-2'' shackle set ready to go on, if im only going about 3.5'' do i need to shim the leafs? i have read that if you run extended shackles you need to shim?

[treefrog]

Put it together and drive it. If you have driveline vibrations, get yourself an angle finder and measure your driveshaft angle. If you are NOT running a CV driveshaft, your pinion and transfer case output should be parallel. If you are running a CV driveshaft, you pinion should be pointing directly at your transfer output shaft. Degree shims come in varying sizes for you to choose from to dial it in. Another alternative is a transfer case drop, but I am not a fan of those as I cannot see giving up ground clearance you just got by installing a lift. (it's your Jeep though) Take the time to set up your angles right and your u-joints and bearings will thank you later. Half ass it now and you will be changing u-joints on a regular basis wondering why you are rebuilding your transfer case sooner than all of your buddies.
It's really not hard, but every Jeep is a little different. What works for your buddy with the same setup may not work for you.

[JavaTee]

The only issue with shims is, the tendency for the bolt that holds the spring pack together to break due to the extra force applied to it.
My suggestion is to grind off, and reweld the spring perches to there new/needed position. That's the beat/safest way to do it.
Later, T.J.

[Cali94YJ]

treefrog and JavaTee are both right. I just had a Rubicon D44 installed in the back of my YJ with a SYE. I had the stock D35/drive shaft with shims and shackle lift, my rear u-joints grenaded. It ripped the muffler apart. Happy it was at a low speed and didn't pole vault the drive shaft in the ground and flip my jeep. Transfer case drop pucks are garbage unless you like to re-torque after wheeling. If you do shim, buy the steel ones instead of aluminum, unless you like to re-torque after wheeling.

[Hamr25]

ok so looks like im shimming. im running an np242. i know that i dont have/need a sye. would this make any difference is shimming?