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

https://theultimatejeep.com/notfound.png

[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? :p

[Matt]

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

[jjt250]

Hey Matt, I got stock WK CRD springs lying around. I'd be happy to take some measurements if you need any. For what it's worth, there was a noticeable different just by eye when I was comparing Hemi XK springs with my stock WK CRD springs so the OME catalog could be using any WK/XK spring.

[Matt]

That would definitely be helpful man... more info the better!

[paroxysym]

LOL youre crazy matt... but this is educational and ill be staying tuned.

[07JeepXK]

Matt I'm kind of confused. So you said the minimum lift height could be 1.5 inches using the Bilstein struts and the OME MD spings. If the struts at the lowest setting give you 3/4" of lift with OEM springs, how are you getting 1.5 inches as the minimum lift when paired with OME MD spings? Is this due to cutting the springs making them shorter? Because the OME MD springs alone will give you 2 inches of lift.

Ok once you explain that, I need you to help me achieve 1/2 inch more lift then my current OME struts and HD springs by using Bilstein struts and MD springs. Is this possible?

[Matt]

Adam, yes the 1.5" height is due to the cut springs not providing as much lift as un-cut springs (but they'll have a higher spring rate).

Is there a reason you want to use MD springs? The reason I'm using MD springs as my starting point is because the spring rate increases when you cut the spring, and I like the HD spring rate; so I'm basically turning the MD springs into a "shorter" HD spring.

If you want to drop down to the MD spring rate, you could run them un-cut in the 5100s; i'd probably try the middle lift setting and see where that puts you. If it's not high enough once everything settles you can bump them up to the highest setting if needed.

If you like your HD spring rate, and don't have any aspirations to run a modified superlift then you could just get the 5100s and put them on the lowest setting with the HD springs. I believes there's a few WK's running that setup already.

and just to completely derail us....Have you thought about the ICON coilovers? :cool:

[07JeepXK]

Well I already have a 4 inch lift in the rear of my XK so I'm half way there. Getting the front components some day could be a possibility. So like you, if it ever were to happen I would probably run a modified Superlift and net about 5 inches of lift. Again I don't know if I'll ever get the front components but if I did it would be nice not to have to go out and buy all new struts and coils once again, I can just do it right the first time.

I do like my HD springs but think if I were to pair them with the Bilsteins at the lowest lift height my cv's and tie rods will be at a greater angle than my liking. I figured since you can gain 3/4" of lift from the Bilsteins at the lowest setting that the MD springs would work nicely. Especially since I could always cut them and bring the spring rate up closer to the spring rate of the HD's and just adjust the struts if more lift is needed once they are cut. I would definitely not want to do any cutting of my current HD springs since the spring rate would go up even more.

I don't think I'd ever spend the money for coilovers on this XK, maybe when I get a Hemi. If I'm spending any great deal of money on the 4.7 it's getting RCV CV Axles.

Why is it that when you cut the springs the spring rate goes up. That's another thing I really never understood

[Matt]

Roger that... so yea you basically want what i'm trying to do. I'll be the guinea pig this go around so hold tight for another month or two and we'll see how it works out :)

Trying to think of the easiest way to explain how/why the spring rate increases when you cut the spring without getting too technical.
[erased 3 different things I typed...]
In the fewest words possible- there's less material to "deflect". As you remove spring material from a coil spring, which is basically a torsion bar, it requires more force/torque to achieve the same amount of rotation.

Trying to explain this with an intuitive type example...thinking about torsion bars because they're easier to visualize and because coil spring equations are derived from torsion bar equations.... using the image below what does your gut tell you if I ask you this question, "if we shorten the bar a lot, does it get harder or easier to twist it the same amount?". And conversely, if I make that bar really really really long, does it get harder or easier to twist it?

https://theultimatejeep.com/images/imported/2013/11/TorsionBar_withload-1.jpg

To give an equation type response.... The spring rate (k) of a coil spring is calculated as follows:
k = (some variables) / (some other variables x the number of active coils)

So since the spring rate is inversely proportional to the number of active coils (given the other variables remain constant), as the number of coils decreases, the spring rate increases.

...if that doesn't help, you can come help me install my parts next month and we'll chat it over a few beers and greasy/busted knuckles :cool:

[07JeepXK]

That makes sense.

[Matt]

Jacob could you post up more pictures of that spring? Need to estimate the number if effective coils so I can calculate the stock spring rate (assuming material properties similar to OME)

[hoaxci5]

https://theultimatejeep.com/notfound.png

https://theultimatejeep.com/notfound.png

Rears - just so they shown somewhere.
Small Diameter at top and bottom 5 3/4" (14.6cm)
Larger Diameter of center coils 6 3/4" (17.15cm)
Overall length 13" (33cm)
Space between coils 2 1/4" (5.72cm)

https://theultimatejeep.com/notfound.png

https://theultimatejeep.com/images/imported/2013/11/329087_3046476053074_1769547402_o-1.jpg


All the springs are stock 2007 Hemi Commander with tow package (I think the tow package made a difference in springs somewhere didn't it?)

[paroxysym]

the more i thought about this, the more im intrigued by your findings..

im trying to see what to match the OEM hemi coils up front with in the rear- when i throw them in the front with the 5100s adjusted to 2".

[Matt]

I've been racking my brain about how to decide how much i want to cut off.... I can always cut more off (or drop down a setting) but I'd prefer to get it right the first time :p

To cut out the variables with the stock springs, I'm taking a new approach and basing my "target height" from where I sit right now with OME HD springs/struts.

My front is currently 22" hub-to-fender with OME HD springs, OME struts and 1/4" strut spacers.

OME HD springs are 14.37" extended and have a rate of 630 lbf/in. I measured the spring at static ride height and its right at 11.25"; which means each strut has approximately 1965 lbf.

EDIT: I forgot to factor in the 2:1 lift ratio in my original post

Using that load, the following OME MD springs would produce less lift as shown:

OME MD uncut = 14.56" free height w/530 lbf/in rate = 10.85" @ equilibrium = .40" less = .80" lower
OME MD .5 cut = 13.74" free height w/560 lbf/in rate = 10.23" @ equilibrium = 1.02" less = 2.04" lower
OME MD .75 cut = 13.33" free height w/580 lbf/in rate = 9.94" @ equilibrium = 1.31" less = 2.62" lower

That's not taking into account the 1/2" lift i'll be losing from removing the strut spacer as well. Adding that I get:

OME MD uncut = 1.3" lower
OME MD .5 cut = 2.54" lower
OME MD .75 cut = 3.12" lower


Soooo, I think i've convinced myself that cutting one complete coil off is a bad idea to start with.

I feel like i'm missing something... gonna have to chew on this one a bit more or maybe just start with an un-cut spring and see where I end up.

[Matt]

Just for giggles....

OME HD 14.37" free height, 8.9 coils, 630 lbf/in
HD 1/2 coil cut = 13.56" w/667 lbf/in = 10.61" = .64" less = 1.28" lower (1.78" lower w/spacer removed)
HD 1 coil cut = 12.75" w/710 lbf/in = 9.98" = 1.27" less = 2.54" lower

I feel like these figures are over-estimated... likely due to the difference between "coils" and "active coils" which does factor into the calculations (I've been assuming they're all active coils); let alone all the other guestimates i've been working with. I'm thinking the "free height" might also be measured from the center of the wire, not from the edges of the spring.... that'd definitely throw these figures off.

Case in point there are guys running a modified superlift with 1 coil cut off an HD spring. Using these assumptions/estimates cutting that one coil would nearly negate the initial lift achieved by that spring.

[06JeepXKHEMI]

Matt, your genius talk confuses the **** out of me... That being said, why cut a coil at all with the HD springs at the lowest setting on shock?

Sent from my SGH-T999 using Tapatalk

[Matt]

That being said, why cut a coil at all with the HD springs at the lowest setting on shock?


Because I want to run these on the lowest setting when i install the Superlift.

The goal is to have an adjustable strut setup that nets ~3" lift on the highest setting and then can be adjusted down to ~1-1.5" when you install the superlift for a ~5.5" lift.

If I just put the 5100s on the lowest setting and use HD springs, I won't have the ability to adjust them down at all. And when I go with the superlift i'd like to have a stiffer spring than stock, which is achieved by a cut OME MD spring.

..... and don't worry dude, I confuse the $(&% out of myself daily :p

[Matt]

I think im gonna have to stop driving myself crazy and try taking a more qualitative approach..... then cut some damn springs and install them and see what happens :p

OME MD = 14.56" free height
OE Spring= 13.25" free height (1.31" less than OME)

Cut OME MD spring rate > OME MD spring rate (530) > stock spring rate ... so regardless of what it ends up being, its a heavier rate than stock.

I'll double check the measurements when I have the springs here, but if 1/2 coil cut off the OME MD gives a 13.75" free height, that's 1/2" over stock which should yield ~3" lift with the 5100s on the highest setting, not including additional lift from the increased spring rate.

So there it is, i've convinced myself to cut 1/2 coil again. Lets see if it sticks this time lol

[07JeepXK]

Why not just install the OME MD springs on the Biltein struts without cutting a coil? See where that gets you and then go from there. Because once you start cutting you can't go back. If it's not what your looking for take it apart and then cut the coil and/or make adjustments to the strut as needed.

I just want to know how I can get about 1/2 inch more lift then I currently have. My OME struts are shot so those will need to be replaced right from the start. And I almost wouldn't mind a hair less spring rate than the OME HD springs.

[Matt]

Yeah Adam thats kind of what im torn with doing. My gut tells me that the uncut spring + 5100s @2" is going to be way too much. But you can always cut more off.

Though as long as my cut OME spring is taller than my stock spring I should get more than 2". If its 1/2" taller and has a higher spring rate I think ill easily be in the 3" lift range.

Either way once ive played with it you'll know what to order :)

[06JeepXKHEMI]

I guess this all makes a little more sense, but your math situation is way to intense for me hahaha.. I was trying to comprehend how cutting a spring would still yield lift, yes I know a stiffer spring will net more lift, hence the advertised 2" OME HD actually gives you closer to 3". By cutting the spring it increases spring rate which will negate the amount of lift??? Am I getting there Matt??? hahaha I feel like Im in school, but a fun school

[Matt]

Lol you're almost there man...

Cutting a spring increases the spring rate, but decreases spring height. The loss in lift is a result of the loss in spring height which has a much larger effect than the lift from increased spring rate.

So basically all im doing is calculating the final spring height for a given load. Comparing the final equilibrium spring heights is an indication of how much ill lose/gain from my current setup. But somethings not adding up so I think the free heights ive calculated for the cut springs are wrong (ill verify when my new springs get here)

You can pretty much ignore all my numbers. Im really posting them all more for the sake of documentation so I can come back here and read what ive done.

[06JeepXKHEMI]

Trust me Im looking right passed those numbers, math is not my strong suit by any means!!! I think I see where you're going but Id have to agree with Adam, go with uncut first and see where you're at, then start cutting

[Matt]

It would be easier if I still had a 3rd vehicle so im a bit more pressed for time this go around.

I'll measure the spring and if I can take 1/2 coil off and still be at least a half inch longer in length than a stock spring, that should all but ensure 3" lift. If I end up a little short I can always slip a strut spacer in with relative ease :)

[07JeepXK]

So are you planning on running a MD spring with 1/2 coil cut and the Bilsteins at max lift. Then when you install the Superlift drop the struts down to the lowest setting?

[Matt]

^^ exactly :)

[07JeepXK]

Stupid question Matt, but how exactly does the Bilstein strut achieve lift? Does the strut itself get longer by adjusting it to achieve the lift or does the lower coil mount move keeping the strut the same length? If it's just the lower coil mount that moves and the overall length of the strut doesn't change wouldn't that throw your numbers off as far as how much lift you will get?

[Matt]

The overall length stays the same and the lower perch moves upwards to add preload, which I've accounted for (the additional preload has slightly different effect on lift depending on spring rate).

However an unknown right now is how long the actual 5100 series is which may provide some lift itself. That's something ill have to measure when they get here and adjust the amount I cut accordingly.

[paroxysym]

matt this may be off subject pertaining to this- but it involves the 5100s... would the spring rate go up or stay the same when you add an OEM Hemi coil to the 5100s adjusted to the highest setting of 2"? If the spring rate increases, what is it at that setting? thanks for your help dude.

[Matt]

The spring rate does not change.

I wish I knew the spring rate of the stock hemi coils but Jeep wouldn't disclose that info when I contacted them.

[thance]

With OME HD springs and struts, a 3/8 spacer and using the extra space in the strut bolt hole to my advantage I have about 4" of lift up front. In fact I attached the plow yesterday for the first time since playing with the suspension early in the year and it is a 4 3/4" off the ground. Not very useful. I need an adapter to drop it.

Anyway, I can see the adjustable struts being fun, but not sure that you get any more lift, just more possibilities.

[Matt]

Im not looking for more lift, im looking for the same lift with the ability to lower it at a later date.

[Matt]

My OME springs came in yesterday and now I see where the issues are in the calcs.

The free height spec is correct, but as I though, the 8.9 coils includes the closed & ground end which is not considered part of the "active coils" for the estimates. It also throws off the adjusted free height estimate a bit. Another issue I found is that the top coil is actually closed as well (last coil flattended). Cutting this section off doesn't change the spring rate much.

With 1/2 coil cut off i'll be ~14.25" free height
With 3/4 coil cut off i'll be ~13.75" free height
With 1 coil cut off i'll be ~13.38" free height

I think i have an idea...need to go measure my XK again

[Matt]

CLIFF NOTES: If i cut 1/2 coil off the MD spring and set the 5100s to the highest setting, I think i'll end up .25-.8" higher than I currently sit (depends on the final spring rate). So i'm going to do that first since I can always cut more off or drop the 5100s down to a lower setting if its too high.

Cutting off half coil basically gives me the same free height as the OME HD, but with a lower spring rate. Assuming the spring rate doesn't change (to be conservative) The cut spring will reach equilibrium at about 10.6" which is about .65" more compression and approx 1.3" lower ride height. Add in the lost 1/2" from also removing my strut spacer and I'd be 1.8" lower than my current setup.

Add in the ~2" from the 5100s and i'm looking at ending up about .25" higher than I am now. And that's being conservative.

If I assume the last half coil is active that would result in a new spring rate of ~570 lbf/in for a compressed height of 10.9" resulting in ~.7 lower ride height. Plus the extra 1/2" from spacer and i'm looking at 1.2" to make up with the 5100s. So i could end up with about .8" more lift than i currently have (too much). If that happens, I can always drop the 5100s to the middle setting or cut more off the spring.

[06JeepXKHEMI]

Matt, when are doing this?!? I think Im finally catching on to this hahaha

[Matt]

If my struts and UCA's show up today.... maybe tonight/tomorrow. I'd like to get it done this weekend so I can let everything settle and then adjust them if I need to while im off during the holidays. And my bumper will be here next week so i'd prefer to have some free time to do that too!

[06JeepXKHEMI]

Big things happening!! I like it

[paroxysym]

matt, i was looking through johns 1" lift thread and he has the following spring rates listed for OEM coils:

- Hemi XK 601lbs
- CRD 473lbs (d), 433lb (p)

[Matt]

I wonder where he got that # from. That seems a bit high based on how much stronger the OME HD springs felt compared to my stock ones.

I always assumed that the stock rate was lower, even if just slightly, than the MD springs. ... I guess ill find out soon enough :/

[jjt250]

Hey guys, I got that number from Diesel Power Mag's build of their 2008 Jeep Grand Cherokee. I'm not sure how accurate those numbers are or how they got that information. Here's a link: http://www.dieselpowermag.com/tech/general/0808dp_diesel_jeep_grand_cherokee_road_test/photo_09.html

[Matt]

Awesome man thanks for the link. lol but damnit I hope that's wrong, i didn't want a weaker spring than stock :(

Maybe it's a typo and they meant 501 [wishful thinking]. I forget what the weights are, but I didn't think a Hemi XK was all that much more than a CRD WK to warrant 130-170lb more spring rate. I guess it's possible though.

[jjt250]

You could be right about a typo, Matt. The CRD weighs a little more than a Hemi and I don't really see why the XK would weigh that much more than a WK in the front. All I can tell you is that there definitely was a noticeable difference (just by eyeing them) when I compared the two springs side by side. Ride is a little stiffer and gave me probably +1/4" of lift. So over 130lb stiffer spring rate? I'm not so sure. I never got around to it, but I still have my stock CRD springs laying around if you need me to take some pics and measurements. Not sure how much that'd help you, but just let me know what you need and I'd be happy to help!

[07JeepXK]

I hate to say it Matt but maybe you should have not cut the spings and went from there. I could be totally misunderstanding all this though. Hope it all works out for you!

[Matt]

What gets me is that i found pictures of XK's running the OME MD and the front was lifted ~2". I didn't want to add 2 more inches on that.

Hopefully the little bit I cut off will work out. If i'm 1/2" lower than i want to be i can always throw some strut spacers in.

[07JeepXK]

Well let me know cause I need front struts bad and want more lift at the same time

[JustinS]

I hope my 5100's show up today :(

[paroxysym]

I hope my 5100's show up today :(

whered you order from? heard they were on backorder

[JustinS]

whered you order from? heard they were on backorder

Kolak on jeepforum. He had them in stock.

[Matt]

To add a positive spin to this thread, the additional weight of my rear bumper and leverage from the tire lowered my rear about 1/2". That adds some slack with where my front can end up to still be in my "happy" range. 1/2" higher than it is now would be nice, but a 1/2" lower isn't the end of the world either.

[Matt]

It looks like my guestimation of .25-.8" taller is pretty much spot on. Passenger side is still apart due to other issues, but I've gained about 1" as of now. I expect it to settle some so figure somewhere about 1/2" taller than my OME HD + strut spacer setup.

Looking forward to getting the other side done so I can test drive.

https://theultimatejeep.com/images/imported/2013/12/20131226132035_zps67d76931-1.jpg

[06JeepXKHEMI]

How was the install besides the problem with lca? What's the angle of cv looking like with extra 1"

Sent from my SGH-T999 using Tapatalk

[Matt]

I'll get pics once its all back together. The extra inch is too much but once it settles I think it'll be workable.

[Matt]

Ok it's finally back together and looking pretty good.

With a full tank of gas these are my ground-to-fender measurements:

LF / RF
LR / RR

BEFORE:

37.00 / 37.25
38.00 / 38.25

AFTER

37.50 / 37.75
38.00 / 38.25

I'm guessing it'll settle another 1/4" or so... even 1/2" isn't a big deal (I like the rear about 1" higher)

Will have to get some pics tomorrow.

[07JeepXK]

If it settles a half inch you will be sitting the same height as your old setup

[Matt]

That was my goal. Equal to or slightly higher

[07JeepXK]

Good point. When you getting the Superlift?

[Matt]

unfortunately, not in the very near future. Between the rear bumper, other issues and the LCA i just had to buy, my Jeep mods for 2014 are going to be extremely limited.

[07JeepXK]

I hear you. I have been falling behind on the Jeep due to lack of extra funds. My rear brakes are practically metal on metal, front struts are shot, rear Superlift shocks are garbage and clunk like crazy (they have been installed less than a month) and there are a few other things that need to be done to it. Good thing I get full time at the Jail in less than three weeks!

[lekmedm]

...rear Superlift shocks are garbage and clunk like crazy (they have been installed less than a month)...

I have 25k miles on my SL shocks and going strong.

Sent from wherever my Jeep takes me.

[07JeepXK]

I have 25k miles on my SL shocks and going strong.

Sent from wherever my Jeep takes me.

Which ones are they. The white ones they send with the kit or the upgraded ones?

[lekmedm]

Whatever came with the kit. They are white.

Sent from wherever my Jeep takes me.

[07JeepXK]

Yeah those are the same shocks I have

[Matt]

Looks like some strut plates might be in my future; down to about 37" today. Gonna have to get some sand bags to put in the back soon :p

https://theultimatejeep.com/images/imported/2013/12/20131229084531_zpsa79ac101-1.jpg

[JustinS]

I guess I'm confused, why'd you go through all that work to be at the same height? Since you're thinking of adding a strut spacer it looks like you shouldn't have cut the springs. ..

[Matt]

I guess I'm confused, why'd you go through all that work to be at the same height? Since you're thinking of adding a strut spacer it looks like you shouldn't have cut the springs. ..

I've mentioned it a few times... but it's a step towards a 6" superlift. (I was planning on doing the SL later this year, but did the SA bumper instead)

Right now it's at the same height I was before. I just don't want it to go any lower; adding the strut spacers isn't the end of the world if needed. Being the first to try something isn't always the easiest, especially for something like this with all the variables.

Edit: Right now it's about equal to the OME HD setup + 1/4" strut spacer. If it goes down lower than we'll know that it's equal to just the height of just the OME HD, so i'd have to add the spacer back in to get where i was.

[07JeepXK]

When Matt installs the Superlift he can drop the struts to the lowest lift setting and net around an inch to inch and a half more lift to the 4 inch Superlift bringing his ride hight to about 5 1/2 inch of lift up front

[JustinS]

When Matt installs the Superlift he can drop the struts to the lowest lift setting and net around an inch to inch and a half more lift to the 4 inch Superlift bringing his ride hight to about 5 1/2 inch of lift up front

I get that aspect, I would have just waited till I had the superlift and done it all at once because I'm lazy lol

[Core XK]

I get that aspect, I would have just waited till I had the superlift and done it all at once because I'm lazy lol

The REAL reason was because Christmas was my birthday, and Matt wanted to give me a modified OME lift for a bday gift :)

[pjmjr508]

Your Rig is looking great

[Matt]

Thanks PJ!

And another reason I wanted to do it now was to spread the cost out. Timing worked out with Corey wanting new struts/springs too :)

[07JeepXK]

Did Corey reuse your struts or buy new ones

[Core XK]

Did Corey reuse your struts or buy new ones

I used his entire setup. Only changes were some fresh silver paint.

Sent from my SCH-I535 using Tapatalk 2

[07JeepXK]

Nice. My front struts are shot. Have had them about two years now and it's time for bilsteins

[Core XK]

2 years and they are shot? How much do you wheel? Lol

Sent from my SCH-I535 using Tapatalk 2

[Matt]

2 years and they are shot? How much do you wheel? Lol

https://theultimatejeep.com/images/imported/2013/12/ADAM_zpsef31b3b2-1.png

[07JeepXK]

2 years and they are shot? How much do you wheel? Lol

Sent from my SCH-I535 using Tapatalk 2

Not as often as I'd like to. But when I do it's no green trail at RC haha. The struts have been shot for a while. When I just replaced the rear OME shocks with the longer Superlift shocks, one of the rears were blown


https://theultimatejeep.com/images/imported/2013/12/ADAM_zpsef31b3b2-1.png

Nothing is Adam proof on my Jeep

[paroxysym]

Forgive my ignorance but with the 5100s, do they limit the lift height to 2" or is it 2" + whatever the springs would net you? Cause I see that running the 5100s on 2" with stock 4.7 springs gets your right around 22", I'm wondering if running them on 2" with hemi springs on my 4.7 will net me more than 22"

[Matt]

It's 2" +

To think of it another way, on their highest setting they add up to 2" lift on top of whatever spring you have in there.

[Matt]

You could be right about a typo, Matt. The CRD weighs a little more than a Hemi and I don't really see why the XK would weigh that much more than a WK in the front. All I can tell you is that there definitely was a noticeable difference (just by eyeing them) when I compared the two springs side by side. Ride is a little stiffer and gave me probably +1/4" of lift. So over 130lb stiffer spring rate? I'm not so sure. I never got around to it, but I still have my stock CRD springs laying around if you need me to take some pics and measurements. Not sure how much that'd help you, but just let me know what you need and I'd be happy to help!

Jumping back on this topic out of pure curiosity.

I think the 601 spring rate has to be wrong. I just measured the stock Hemi coils, the wire is .66" (basically 17mm).

Looking at the OME Springs, going from 19mm to 18mm wire drops the spring rate a full 100 lb/in. Given the same # of coils and assuming similar material properties, going down to 17mm wire would bring the rate down to 430 lb/in (close to the advertised 440). Although I counted 8 coils as opposed to the 8.9 coils for the OME springs, so that bumps the rate up a bit.

Accounting for the difference in number of coils, the Hemi springs I have here should be around 480 lb/in based on very rough estimates.

To bump that up to 601 would require some high-end spring material (not likely for production vehicles). However, 501 lb/in seems very possible..

If you don't mind measuring, what's the diameter of the wire on the CRD coil and the number of coils? (if you can, use a caliper to be accurate, it's hard to eyeball diameters to the mm increment)

[paroxysym]

so does that mean the hemi XK springs mostlikely have a higher spring rate than the OME MD coils?

any estimates what those on a set of 5100s set to 2" would net me? 2.5?

i saw ground to fender measurements- do you have hub to fender? ive see 2 people post measurements with the 5100s- a 4.7 WK with OEM springs and a rustys strut spacer netted 22.5", and a CRD WK with OME MD springs and the 5100s set to .75" netted 22".

[Matt]

No i believe it's something along the lines of:
Hemi Spring rate = 501
OME MD Spring rate = 530
My cut OME MD Spring rate = 560
OME HD Spring rate = 630

My front hub to fender is just a hair over 22" as it sits (37" to the ground). I'm not sure what that correlates to for a WK since the fenders are cut different and I believe are higher.

Being that you have a 4.7L and i'm not sure what your stock spring rate is, i'm not sure how much extra you'd get from the Hemi XK coils + 5100s. But ~2.5" is probably a good ballpark.

[Matt]

Took the jeep for the first long drive & alignment today. Aligned perfectly (I actually got the camber/caster on the passenger side right on in my garage, just had to adjust the driver side).

After the drive (~70 mile round trip... so about 100 miles total on the new setup) and the alignment, im still above 37" on both sides (actually about 3/8" higher) so i'm feeling optimistic i won't need those strut spacers. But i have them on hand anyways.

[Matt]

Well i'm another week and a couple hundred miles in.... front's still at 37.375 (3/8).

I've never measured the front end as often and accurately as this time. I'm thinking the initial settling was the springs, but since I wasn't driving the vehicle the struts never broke in and there was still a lot of stiction in the bearings/seals and/or the top-out stop needed to break in. Either way, i'm pretty confident that I won't need the JBA strut spacers AND i'm happy I cut as much off the springs as I did.

Just measured again today (full tank of gas) and i'm pretty confident calling these the "final" numbers:

LF / RF
LR / RR

BEFORE:

37.00 / 37.25
38.00 / 38.25

AFTER

37.38 / 37.38
37.90 / 38.00

[skynyrd]

Hey do you happen to have the Strut Part #? I see 5100's offered on a couple different jeep sites but when I called Bilstein about them they said they don't have a 5100 adjustable for my 2010 Commander.

[paroxysym]

Hey do you happen to have the Strut Part #? I see 5100's offered on a couple different jeep sites but when I called Bilstein about them they said they don't have a 5100 adjustable for my 2010 Commander.

24-225793, bilstein 5100 adjustable fronts

[JustinS]

Hey do you happen to have the Strut Part #? I see 5100's offered on a couple different jeep sites but when I called Bilstein about them they said they don't have a 5100 adjustable for my 2010 Commander.

They've been told they fit but have yet to update their part numbers. A little aggravating.

[skynyrd]

24-225793, bilstein 5100 adjustable fronts

Ok cool thanks. That is what I have on order. Hopefully they won't take forever.