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do flat (stock) yj springs have beter flex than arched on a SOA

4584 Views 11 Replies 2 Participants Last post by  Jeepskate
This is going to be SOA
do flat springs give better flex than arched? if so than why do so many people run a arched spring, than to gain the flex back they do shackle reversal and buggy springs, well if they are using the arch springs for more lift, than why not add a small shakle lift and a small body lift to compansate for the use of the flat springs.
the reason why i ask is b/c i am building a wrangler soa and was thinking of what is the best type of spring to use!
84 cj7

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> do flat springs give better flex than arched?

Yes and no. It's sort of a balance using flat springs...pretty much have equal up and down travel (there's more that factors into this, but let's keep it simple). An arched spring will potentially have more up travel, but less down travel since some of the down travel is 'used up' on the arch.

> if so than why do so many people run a arched spring, than to gain the flex back they do shackle reversal and buggy springs,

For potentially more travel in both directions and the ability to run a slightly larger tire if they wish.

> well if they are using the arch springs for more lift, than why not add a small shakle lift and a small body lift to compansate for the use of the flat springs.

That potentially gets you more up travel while down travel remains about the same.

Hey Man,

Check this out:

This should answer your questions. I will be doing this swap shortly.

Good Luck

New England 4x4 Club
79 Jeep CJ7
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would a shakle reversal kit and a buggy leafs in the front help get more flex out of the stock springs? The reason why I do not want to run the arch springs is because I am trying to keep it as legal as possible I know that the shackle reversal gives about a 1 inch lift.

The buggy's will get you more droop and you'll get a minor increase in uptravel from the buggy vs. a fixed frame sleeve.

You should know that not all shackle reverse kits give you additional lift. You need to ask about this for the kit you're considering. I know the kit from M.O.R.E. does give you an inch of lift. Whereas the FST kit (from Fly-N-Hi) does not. I don't know about the other kits out there.

Here is what an ol' Jeep builder told me after I mentioned that I want to do a SOA and run 33's to 35's (rock climber). He said, "Well, since the SOA gives you about 5" of lift, I would break apart the spring pack and leave the first three springs (the long ones). You'll have plenty of clearance and the long springs will allow you to have some pretty good flex.".

Makes sense to me and when I get around to doing my SOA, this is what I plan to do. I might add either Hyper Shackles/Revolver Shackles and a SRS when I do it as well. Of course, right now I have the Warrior 1 3/8" shackles. I'll leave them on when I do the SOA and spring thing. I'll let you know how it goes....

I'm no old time Jeep builder, but removing leaves from the pack will give you less lift (the thickness of the spring packs factors into the amount of lift you get) and may also make spring wrap more likely, so plan on some anti-wrap bars. You also might consider using Blazer springs that have the main eyes wrapped under instead of over...these are supposed to be more resistant to the fatigue and ultimate sagging.

wouldnt removing springs from the packs cause severe axle wrap as well??

New England 4x4 Club
79 Jeep CJ7
Yes sir SEVERE axle wrap since it lowers the spring rate of the springs

[email protected]
'84 C-J-7 -
This evening I've been a blessed man. I've learned about puppy dog tales, 'gator tales, bear tales, snake tales and 'hot' tires on frozen snow and probably other things I didn't know I didn't know anything about. I've taken and taken and taken and I can't take any more! So I guess I'll give a little. I know virtually nothing about any of the above (".....kept pulling the dog back into the pile...." - how you gonna verify THAT story? Ask momma bear? Around here we used to call something like that a TAAAAALLLLLLL Texas tale!) but I do know something about a spring-over configured Jeep. I did mine back before it was poplular (I don't mean to hint that I'm a pioneer here; I'm not.) and have lived with the results for nearly five years and some eighty thousand miles. So with your indulgence I'll start a long dissertation on said subject and if I am too long winded then use the delete key, huh. I will say in advance that it will not be as long a piece as TeamRush on ignition systems, though.

a) The amount of lift is measureable exactly. In advance. It is the dimension from the bottom of the existing spring pads to the top of the new ones when in place. For a stock sprung YJ for instance, it is 5-3/4". (That is with the Rubicon Express anti-wrap pads.)
b) I did it in one weekend working hard. It was semi-sucessful.
c) You will have to get the slip yoke eliminator kit. You have no choice unless you like tearing up machinery that costs money to fix. The drop down kits (an unfunny joke) do not solve the problems created when doing the SOA.
d) You will have to move the brake line mounting points as well as the parking brake cable mounting points. You will not have to buy extended brake lines, though.
e) Your shocks will not be correctly sized if you use one of the cheap kits. Either the up or down travel will be compromised because of using the stock mounting points.
f) You will have to get a Constant Velocity (CV) equipped rear drive shaft custom made.
g) You will have to learn to drive your Jeep all over again. (That is an exaggeration, of course, but is merely a way of emphasizing that the handling characteristics will change dramatically.)
h) You will ruin the springs starting with day one and will have to replace them. More on this later.
i) You will have to either be a good fabricator or have access to someone who can do this for you. This is NOT a simple bolt on deal. It will take a lot of tools and equipment. It is a challenge and is not particularly fun fun fun. It is however, enjoyable for reasons to follow.
a) There is nothing else you can do that will give you this much increased off-road ability for this relatively small amount of money and effort. I have stated on this board and in other venues that I regularly keep up with people who have MUCH more money than I in their rigs. I cannot leap tall buildings with a single bound like they sometimes can, but I have pulled them out of many a tight spot because I got through when they didn't.
b) You get to keep the soft ride of the YJ. When I get to ride in another 'lifted' Jeep with arched springs (brands X,Y & Z) I am glad that I have done what I have done.

Now let me address some of the negative points raised earlier.
1) Use a custom drive shaft from Tom Woods. He is genuinely one of the finer people in business anywhere and the price and delivery is perfect. 'Nuff said. Do it.
2) Assuming that you have a sway bar disconnect already on your vehicle, cut off the lower shock mounts on all four corners and use simple 3/16" plate brackets and make new ones on TOP of the axle and you can use the stock shocks if you want. Mine were the custom designed Bilstiens used by the factory on the Sahara models and they are as good as you can get for this application for the price. Do it.
3) When I said earlier it was semi-successful I meant that the kit did not solve all of the problems on the first weekend. Nothing that costs $400 and makes the big changes to all of the engineering of the factory Jeep will do that. Mine is now successful and has been since about a month after the first weekend. Pay attention here and on the other locations on the net on the subject and you will be successful in less time than the rest of us and spend less money in the process. Do it.
4) You will ruin the springs. You WILL ruin the springs. Just by driving your Jeep. You will ruin your springs faster if you use your Jeep in four wheel drive mode on tough trails and take advantage of the new dimension in suspension travel. Yeah, I know. Use it AND lose it. Bummer, huh? However, do it anyway. It is worth it. Here is what I've done so far on the spring problem. First thing is get another set of Wrangler springs and get the main leaves out of each one and cut the eyes off and using longer spring pack bolts double up the main leaf on each corner. I know I told you that you will be keeping the 'soft' YJ ride. (I lied a little bit but it is not nearly as bad as lifting with high arch springs.) This will make the spring packs last a little longer than they otherwise would. The other benefit is more resistance to axle wrap. And you will have this; extremely on the rear and somewhat less on the front. I have the automatic and 4.0L six with a/c and hardtop and 3.55 gears with 31" BFG all terrains. Caught on video tape when attemptling to climb a 30' cliff and the Jeep stood straight up, the rear axle was rolled an estimated 45 degrees. The springs were a nearly perfect lazy "S". Scary. The main point here is that this is an EXTREME example and the whole thing lived to tell the story. (I just had to have the seat covers surgically removed from my nether end.) I have been driving as I said, all of this time and all of those trails and with more to come it is still worth it. I have replaced all of the springs once and used a set of rears on the front and that lasts longer than anything else but the big problem now is how to make a set last longer on the rear. You see, the problem is that the springs are not designed to take a negative arch. Fords, Shivolays and maybe others have had and some still have negative arch springs and they work fine but I haven't had the money or opportunity to experiment like I need to. I am currently thinking about the fiberglass springs and will probably be getting serious about this in about six months. Do it.
5) The handling characteristics will undergo a transformation. The factory YJ with stock tire sizes and all track/sway bars hooked up will corner like a slot car. I once did a Mulholand Drive-like road with a lowered and zoomied Prelude hot rod in front and a Bimmer in back and it bugged the Bejesus out of both of those Yuppy types that the Oklahoma Jeep could NOT be shaken or left or passed or .......nothing about me stunk that day. This will go away forever. But it will not ruin anything. I still drive my YJ as fast as I want on any road suface or configuration in any weather around any curve or corner and I don't worry about tipping or rolling. I don't have either of the track bars on (Chris Overacker thinks I'm nuts on this) and about a week ago I noticed that the bolt on the left side for the sway bar has gone bye bye and with the hardtop I now get more sway than I want but this is a fixable deal. Point here is that even with it not in effect due to the missing bolt, the Jeep is still drivable and enjoyable. Do it.
6) On the semi-successful weekend I did not do the SYE kit and didn't have the CV 'shaft but learned about the need for them the hard way. The only two things I will tell you here is that the ONLY SYE I would consider is the one by the boys in Louisiana (John White)(can't think right now!) since it is not a compromise on strength. You can get this same kit from Tom Woods also at the same time you get your 'shaft. I got the 2 Low kit at the same time and love it. Do it.
7) One more thing: I got so much articulation that I bent the front driveshaft and had to replace it. The reason (and I've never heard of anyone else having this problem) is that the front drops so far that the drive shaft will bend around the exhaust header pipe AND against the front edge of the skidplate/crossmember. I've since modified the crossmember and moved the exhaust over some. Do it.
8) One more thing: (grin) one of the reasons I got so much articulation is that I opened the spring pack clamps to the 'stand at attention' position and used the stock shackles and not aftermarket. It all helps. Do it.
9) One more thing: (grin)(been here before, huh!) One 'wheeling weekend in Clayton, OK on Upper Powerline going down to Purgatory (since closed) my drag link gave up the ghost. Welded on a scab and about five hundred meters later it folded again. More scab and got out of there OK. Point is that the steering linkage needs to be fixed. My kit came with the dropped pitman arm and at first I used it. One day on the 'ramp' I noticed that the left front was hanging in the air because the tie rod was hooked on the pitman arm. Off it came and that's when I fabricated a stepped drag link which folded later as previously described...and that's how I got to meet a man who has raised tubing bending to a new level of perfection and paid him to make me a good drag link. (If I had measured it correctly the first time it would have cost me $30.)(I didn't and got to meet him again and give him $30 more.)(You otta see the '36 Victoria Coupe that turns 180's in the quarter - he built the frame stuff and it is HIGH art in tube bending.) I would reccommend that you just plan on this from the beginning. Do it.

In case I haven't mentioned it before, I need to do it now: DO IT!

If I have confused anyone I apoligize! If I have omitted any thing please feel free to ask or request clarification.

One more thing - the extra leaf adds another 1/4" of lift which may have something to do with watching Jeepchicks and wannabeJeepchicks climb in and out of my YJ. (So many legs, so little ......... (Help me out here, somebody!)

Do it.


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Amen!! That post should be added to every Jeepers' 'Bible'

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