Custom spring & 5100 adjustable strut combo (1.5-3.5 lift range)

[Matt]

Sitting here drinking my coffee before driving to Maryland... figured I'd capture some thoughts then work on it again when I get home tonight.

Here's my goal:
1) Adjustable strut lift range from ~1.5 to ~3.5"
2) Spring rate close to OME HD, but slightly under

Benefits:
1) Some people want the benefit/ride of OME HD setup, but not a full 2-3" lift
2) Achieves "modified OME" lift height, and can be dropped down to the lowest setting when installing the superlift for an immediate "modified superlift"; lowest setting targets 5-5.5", medium setting will target 5.5-6" lift.

Eventually someone could have custom coils made once I figure out the specs, but i'm going to start with an OME MD spring and cut off calculated ammounts until I reach the desired parameters. Once I get close, the spring wire diameter can be tweaked to make final adjustments to the spring rate.

The specs:
OME990 = MD 14.56" free height , 8.9 coils, 530 lbf/in, 18mm wire
OME991 = HD 14.37" free height, 8.9 coils, 630 lbf/in, 19mm wire

OE Spring rate = 440 lbf/in, 13.25" free height (rate seems low), 8 coils, .66" (17mm) wire

OME990 with 1/2 coil removed:
13.74" free height, 8.4 coils, 560 lbf/in

OME990 with 1 coil removed:
12.92" free height, 7.9 coils, 600 lbf/in

OME990 with 1-1/4 coils removed:
12.60" free height, 7.7 coils, 613 lbf/in

OME990 with 1-1/2 coils removed:
12.10" free height, 7.4 coils, 640 lbf/in

Bilstein Strut:
Lowest setting = .75" lift with stock spring
Highest setting = 2" lift with stock spring, 7/8" added preload to spring (need to confirm measurement when struts arrive)

Process:
For cut OME MD spring, need to find the amount to cut off that gets me closest to the free height and spring rate that'll reach my goal. Since both spring rate and free height are dependent on how much is cut off, I'll err on the high side of the lift range and sacrifice spring rate if needed.

Will be ordering the parts next month and tearing apart my suspension after Christmas since I took a lot of vacation time.

[lekmedm]

Aaah... obsession, mother of innovation!

Sent from wherever my Jeep takes me.

[Matt]

Lol its a sickness. Its so bad that I actually let my wife drive so I could plug away at some numbers. It's an interesting problem since the spring rate increases but the spring gets shorter so it reaches equilibrium at a lower height (which actually works well for what im trying to do.... )

[hoaxci5]

OEM Spring from my Commander

[Matt]

PERFECT!!! Thanks

[Matt]

Now that I know the length, i did some quick calc's and think that stock spring rate from the OME catalog is low... time for an excel sheet so I can play with the numbers a bit.

[hoaxci5]

Does that pic give you everything you need? I should have some other angles if you need them, I have the rear spring pics also..

[Matt]

Does the 13.25 go to the top edge/tip of the last coil?

[hoaxci5]

It's been awhile since I took the pics/measurements but I'm pretty sure I stood the spring up and dropped the tape measure to the floor and read it at the highest part of the spring. All of the measurements were done with a tape measure and eyes so no fancy measuring devices so +/- human error/lazy eye/beer in hand?

[Matt]

lol sounds good. Tape measure accuracy is all i need for this project