SUA lift

[HuntinHopin]

I am in the process of fixing some previous owner engineering on the rear lift of my son’s Comanche. I am wanting to stay spring under axle. I am looking at the add a leaf from BDS but I can’t wrap my mind around how adding a leaf under the axle will give me any lift. In my little brain, if I add a leaf under the axle it is going to push the axle closer to the frame, thus lowering the truck. What am I missing? 

[89 MJ]

The add a leaf will likely have more arch than the springs in your pack, adding lift. It will also stiffen the pack some, also resulting in lift. 

[HuntinHopin]

Thank you Pete for the phone call. You explained it perfectly. In essence, in case someone else is ever searching for an answer, the add a leaf does “lower” the truck by about .25 inches while also lifting the truck about 3 inches due to the forcing the other springs to conform to the spring rate of the add a leaf. Thanks again Pete!  

[ghetdjc320]

I run that exact kit with the add a leaf. It has a nice spring rate and blends well with the pack but there are a couple of items to note. The actual lift is only a hair over an inch as this not made specifically for an MJ. You will need to redrill the center pin in the add a leaf as it doesn’t line up with the offset of the MJ leaf pack. There are pictures somewhere in my build thread that document the whole process. 
 

Are you trying to match this to a BDS 2 or 3” front coil spring? I’m running the bds 3” complete kit. The front does indeed lift around 3”. The MJ has a stock rake of around 2” give or take. So adding 3” to the front and 1” to the rear leaves the truck pretty level but it will squat with any load. A 6.25” long shackle will help significantly and keep it looking a bit more like a truck. BDS also has the rear shock lengths incorrect for this application. The rear shocks in their 3” kit are too long once the springs settle and will bottom out. The BDS control arms, front springs, and add a leaf are all good quality and far better than most others but the bds stock shocks and track bar aren’t so good. The ride quality of the add a leaf in the stock pack is very good though.

 

You could also go with the General Spring 4 leaf spring pack and add some longer (5.75-6.25” eye to eye) shackles. That would net around a solid 2-3” of rear lift which would couple nicely with some good 3” coils or even 4” if you wanted a more “leveled” stance. 

Here is a recipe for a really solid suspension setup for a low-mid lift: 

metal cloak 3.5” front XJ coils

Currie (rock jock) adjustable XJ control arms or possibly metal cloak XJ or TJ arms

Iron man fab track bar kit (standard drop no offset and no drop pitman arm)

Iron man fab steering brace kit

Moog jeep ZJ steering linkage

black magic or centric posi-quiet brake pads

GS 4 leaf spring pack (or a full length add a leaf like bds)

1” Chevy drop shackles (or teraflex shackles)
Fox shocks valved for an MJ from accutune off-road. 
Later model XJ larger sway bar