Hey Kristinandq,
I love it! It rides so much smoother than stock suspension! Brian aka Adamsbro who has the green Explorer 'Hulk' has the superlift which has fairly stiff springs! Now there are pros and cons to each of the setups from what we've seen. Now Brian did his Superlift in March 2012 and I did mine in July 2012 so they are not too far off on age.
There are two main differences between the Superlift and Duff lift. The mounting point of the radius arms and the coils.
- Radius Arms -
Now with Superlift some people have said in the past that the radius arms are 'prone to breakage'. After comparing older threads and posts (circa 2006 where these problems seem to root from) and comparing the set that came brand new with Brian's kit I can safely say that there has been some design changes in the 6 years since and the current arms are basically indestructible. They are most notably thicker than earlier production runs. I don't know the forces required to deform or break one of the current Superlift arms, but I do know after an incident that left Brian with a bent axle (Moab), the arms did not deform, bend, or crack. Infact, as far as the kit components go, all the Superlift parts endured an axle to rock collision at 30mph without suffering any form of damage. The axle (TTB) is the weakest point in both setups. You won't have to question the strength of the components with either lift.
As far as differences in radius arms I'll start from the flanges that fit over the axle (where the bolt hole line up to hold the axle to the arms), the main beam section of the arms, and finally end with the mounting point of the arms to the frame.
Flanges - Practically the same. They both have a generically drilled hole on either side that fits over the existing axle stud holes for you to bolt the arms on. James Duff is a bit more accurately drilled where Superlift did require a bit of prying and slight hole widening to compensate for an inaccurately drilled hole.
Main Beam Sections - Visually different but functionally the same! Superlift has a more traditional look, similar to that of the triangular stock radius arm. It is akin to an I-beam construction and tapers on two straight angles from the axle till it meets the mounting point. James duff has a mono-tube welded to the flange that extends back to the mounting point. Both can take the weight of the vehicle resting/impacting on them and any difference in clearance is negligible.
Mounting Points - Different! Superlift follows in the footsteps of the way the vehicle was originally engineered, using bushings. The superlift comes with new mounting brackets positioned father back along the frame to accommodate the longer arms. These brackets are designed to use the original bushing hardware (although it is a good move for longevity of life to upgrade the FoMoCo brand bushings to an aftermarket bushing like those provided by Moog). The pivot-ability of the arm is improved but could experience some amount of limit. I'm not aware of any threads where this aspect is compared separate from the whole setup. Duff again has a replacement bracket located farther down the frame to receive the longer arm. Instead of traditional construction, they have opted for a heim joint setup that the radius arms pivot on. This leaves the arms completely free in all directions of travel. Now both pivot points have cons as well. The Bushings will wear - but at a nominal rate and is basically related to how often and hard you wheel. The heim joints won't wear due to movement. They are however susceptible to rusting. The fit between the joint and anchor bolt is very close, and if rust develops between the two they seize together. When my bolt seized inside of the joint, it took some serious force with combined pressure and shock (prybars and sledgehammers) to break it loose. This of course blows out the nylon housing in the heim joint and requires you to replace it.
- Coils -
This is the other component that is functionally different in both lifts. The Superlift has considerably stiff coils where as the duff lift has much softer ones. This is mostly due to how each setup is affected by body roll. The Duff lift with its mounting points and shock mounts is fairly stable with soft springs. Now, the Superlift setup doesn't respond as well with softer springs and require a more ridged spring to help control body roll. This may be because Duff uses a progressive rate spring where Superlift uses a liner rate spring.
Liner Springs - These operate in a predictable fashion when subjected to compression forces. They will always compress 'x' distance when subjected to 'y' force, where when the force is doubled the distance will be doubled. A simple example is a spring that compresses 1" per hundred pounds linearly. In this case, when 200 pounds of force are subjected the spring will compress 2", when 300 pounds it will compress 3", 400 pounds 4", and so on.
Progressive Rate Springs - These operate in a progressive fashion. When 'y' force is applied, 'x' distance will slow exponentially. An easy example would be a spring that compresses 1" under 100 pounds of force, 2" under 400 pounds of force, and 3" under 1200 pounds of force.
As with all pros there are cons. The stiffer coil will maintain full lift height longer, but will be a 'rougher' ride. The soft coil on the other hand provides a much smoother ride, but is much more susceptible to sagging, and must be monitored to make necessary camber adjustments with coil sag. The travel on the softer spring could arguably be 'better' than with stiff springs, but I have not seen any definitive comparisons here on an Explorer with a TTB axle. Both are better than stock.
- The End -
Now that my novel is over (and hopefully of some use) I'd like to try to persuade you to come out next time even if you have a stock rig! There is a lot of country surrounding Little Moab and lots of trails that are just plain fun for a cruise whether it is a stock rig or modified one. As for the rock itself it has a good range of obstacle and challenges. I was able to keep pace on one or two here or there, but when it was out of my truck's ability, it became a game of being a spotter instead for the other drivers and getting to see some pretty good wheeling + learning a thing or two. The other advantage for you is you'd be able to see both lifts in person and get to see how both perform in action. Lastly, when I can't make it up a trail in my truck, it is definitely just as fun being a passenger in someone else's!
