rear spring packs...

ok.. i'm starting the "parts-for-my-next-lift" pile..... i need new rear packs... i am looking at a total of 5 to 6" of lift.... this is for my 95% trail-only rig.. the front will be lifted with a RE 3.5" coil and a 1.75" poly spacer.. opinions and pros and cons please....
3.5" RE pack with a 1.75" shackle?
or
4.5" with MJ shackles?
im leaning toward the smaller pack and the shackle since i see it as maybe a better ride and better flex.... i dont want the thing to sit too high in the ass either...
whatcha think?

mike

I have a 3.5" RE pack that I've flexed pretty good. With the RE shackle, I get right at 4.5" in the rear. That's WITH a C4x4 bumper and tire carrier!

I am always in favor of shorter shackles (within reason), for the reason that they are more stable in a side-to-side axis.

Don't assume that taller springs must be stiffer to get the extra height. They aren't (or shouldn't be). The spring rate is determined by the length of leaves, thickness of leaves, and number of leaves. Amount of free arch does not affect spring rate. You can take the exact same set of leaves and bend them into 3" packs or 4.5" packs.

You are correct that longer shackles yield more articulation. That added articulation also contributes to accelerated spring failure. To get 1.75" of lift, you need shackles that are 3-1/2" longer than stock. IMHO (as a stock-height web wheeler and Beezil's favorite target) that's too much.

the shackles i had in mind are a set i have from a budget boost.... never measured them against a stock shackle but they were advertised as 1.75" lift... they are huge!! and very sturdy.. i wouldnt worry about side-loads with them.. but i can see them interfering with the exhaust..
mike

For what it's worth, the offical RE 4.5" setup for the rear is the 3.5" leaf pack and RE shackles.... that way it flexes better

Also, I have 3.5" RE packs on my jeep for about 2 months now with stock rear bumper, but a full size 31" spare and steel rim, and a HEAVY toolbox in the rear + my socket box (also pretty damn heavy) and while @ Moab I had a HUGE containter box with all the fluids (but the damn power steering fluid LOL.....) and some spare parts and nuts and bolts (also very heavy) and I towed a pretty heavy trailer 3000lbs+ both ways and I finally settled to somewhere between 4.25" and 4.5".... so I'd say for your target height, you probably would want the 3.5" (btw, the 4.25" ~ 4.5" measurement was taken while the spare was in teh back and the toolbox and the socket set)

Kejtar

sidriptide said:

the shackles i had in mind are a set i have from a budget boost.... never measured them against a stock shackle but they were advertised as 1.75" lift... they are huge!! and very sturdy.. i wouldnt worry about side-loads with them.. but i can see them interfering with the exhaust..
mike

Click to expand...

I'm more concerned with the twist they apply to the unibody. Longer lever arm = more torque.

RE 4.5" leaf packs, with their shackle sits right at 5.5". Flex is....ehhh..could be better..I'm working with some new shackle set-ups soon, and leaf removal.

I'm running the setup your talking about (tera shackle and the 3.5" springs)

Works well and rides nice.