I really don't know where this all started, aside from someone's individual experience with a particular set of different coils from 2 manufacturers, but I remain amazed that so many people have come to the conclusion that spring rates have nothing to do with ride quality on these jeeps. To make that blanket statement regarding ALL coils based on such a small section of the market is simply not a fair assessment. Yes, I have seen coils from different manufacturers that had different spring rates that rode very similarly and some that have similar spring rates that ride very differently, but that does not give me the liberty to make blanket statements about all coils based on that limited cross-section of the industry.
When we're discussing Old Man Emu coils, the fact remains that spring rates make a HUGE difference in ride quality! Folks can deny this all they want, but I have been involved in literally hundreds of OME suspension installs and sold thousands of these kits. I have seen ride quality affected dramatically by nothing more than a coil swap on the exact same jeep. The fact that someone else installed a set of coils by Currie, Rubicon Express or other manufacturer and found their ratings differed but rode the same is beside the point. Anyone who has installed a variety of OME springs on a TJ would know this as fact and this would be a non-issue. We've seen many a jeep transformed into a much improved ride by swapping a pair of coils and many that rode great before the addition of heavy bumper, winch or swing-out tire carrier that was right back in the game with a heavier coil that carried the extra weight better.
Coil spring manufacturing and testing varies wildly between manufacturers. The quality of the spring steel itself, heat treating processes, wire diameter, ramp angles (# of coils per certain measurement), etc, all make a difference in how a spring will test as to rate and as to how it will ride and handle. Old Man Emu has coil rates that start around 140lbs/in and go up to 250lbs/in- all with the same quality and manufacturing processes.
Anyone who thinks that doesn't make a difference in ride quality is simply mistaken. Some have said they weren't aware that OME even makes coils with that big a difference in rate, (which was the case many years ago) so it's not difficult to see where a person might think spring characteristics are the same if rates are very close.
DPG Off-Road pioneered the low COG Hybrid kits (or "combo kits") as they've been referred to) in the marketplace close to 20 years ago. No one else was doing this at that time and we were actually laughed at for doing it from the "go big or go home" crowd. These kits became very popular for their combination of ride quality, handling and stability for many who weren't looking to go big and didn't want to mess with long arms, drivetrain mods and other issues associated with bigger lifts. Low COG rigs are simply better climbers on steep stuff and more stable in off-camber situations and very steep climbs and descents. Having built these jeeps with everything from 2" to 6"+ lifts over the past 25 years, I would much rather have an OME 2.5" kit with some High-Line Fenders if fitting 35's instead of a 4.5" to 6" long arm. Others feel differently and don't mind the extra height. That's fine. To each their own. Having rolled and totaled a nice jeep with a 6" lift in an off-camber situation, my vote is low COG every time.
I watched this spring rate/shock discussion take place when it happened some years ago. A lot was misunderstood. At the same time OME was introducing the new Nitro Sport shocks, there were a couple of companies that decided to offer kits similar to the packages we had started with, combining OME, JKS and other parts to make a hybrid package.
The main difference was that these companies were putting out kits with the stiffer "ZJ/LJ" coils in ALL of their packages- I believe because they sit slightly taller than some of the other OME coils. We were using that coil combo in our kits before anyone and there is a time and place for them- but in many applications, those coils are too stiff and ride quality will suffer.
The new shocks were hitting the market at that same time. I remember ARB's product literature talking about firmer valving and dampening in the new shocks. I know I was worried when I heard that because OME suspensions have always been known for excellent ride quality. I should've known better, as those Aussies really do put an extensive amount of testing into their products, both in simulated lab torture tests as well as actual on-vehicle testing in the outback of Australia. I had the old shocks on my own jeep and put a set of the new shocks on there 6 months before they were available to the public. I wanted to know for myself if this was going to be a problem. I figured that I could just go back to the old shocks if I didn't like the new one's. Long story short, the new shocks have better handling and control than the old shocks did. I loved them and I stayed with the new ones. That jeep rides GREAT.
Of course, that was on my own jeep. There was the post some years ago about the guy who switched from the newer OME shocks and saw an improvement in ride quality on his jeep. That's fine and I don't doubt his experience. My issue with that is when he said (based on his experience with one jeep) that ride quality on all jeeps is 100% determined by shocks alone and coils have nothing to do with it. I didn't imagine that one post would initiate such a change in what we all understood as fact in jeep suspensions. Ask any credible coil spring manufacturing engineer if spring rates matter when determining ride quality in a particular vehicle. There are simple reasons why the spring rates in my 3500 dually are MUCH heavier than my XJ or TJ. For a vehicle to ride a certain way and carry a certain amount of weight, you simply need a firmer spring to carry more weight effectively. Too soft and you bottom out too easily and have excessive body roll. Too heavy and the vehicle will ride rough. It is what it is.
Many shock absorbers are manufactured with a universal or standard valving. The only differences are mounting styles and compressed ride heights. Old Man Emu is not that way. The shocks they make for a TJ are not the same valving as other vehicles, but are vehicle specific. Valving is tuned for the vehicle it is intended for and testing is done to optimize ride, handling, load carrying capability, anti-dive and anti-squat characteristics on braking and acceleration and more. The newer generation of OME shocks for the TJ are not stiffer because the JK or JL came into production. They are their own specific design.
The truth is that coils and shocks must work TOGETHER for optimum ride quality. If the coils are stiffer than needed, a softer shock will certainly ride better. If the coils are right on, a softer shock will usually just cause more body roll/ excessive sway, less load carrying capability and excess bottoming which I personally dislike every bit as much as a rough ride. I realize opinions differ here, but I lean toward wanting decent handling on the road as well, which is why I might spring a bit firmer and avoid an Anti-Rock in favor of a factory swaybar or Sway-Loc. Again, to each their own on that.
Some guys will experience fairly large disparities in weight when loading for a trip or pulling a trailer, etc, etc. vs their daily drive at home. On my rig, I prefer a heavier coil rate in back to carry that extra weight better when loaded. When back home and the weight is removed, the ride will be stiffer and the height a bit taller. Here is where carrying some extra ballast weight in back will emulate the loaded ride quality even though the load is not there. We can make a firmer coil ride better by adding ballast, but we cannot make a softer coil carry more weight than it is designed for. These are a few of the things to consider when determining coil rates for a particular application.
Then, as most of you know, there are other factors that must be done correctly (tire brand, load rating, air pressure and a few other things associated with suspension components) that must be right for ride to be at it's best.
If a near stock TJ is set-up with ZJ/LJ coils to get an extra half inch of lift, what good is it if it doesn't ride good?
(BTW, a bone stock soft top TJ with ZJ/LJ coils won't ride good- even with a softer shock)
I would rather run a softer 2.5" OME coil and a half inch spacer to achieve the same height, but with a very noticeable difference in ride quality.
While these discussions may never be settled in the jeep community as a whole, it is not complicated in my experience. A jeep that is set up with the right combo of OME springs and shocks is hard to beat when it comes to that elusive compromise between ride quality and handling/control, etc...
