Project XK: My New 4″ Lift from Superlift

Why a New Lift?

About a year ago, I installed a 4″ BDS lift-kit on my Jeep Commander, as previously documented on this site. In that previous post I discussed my reasons for getting a lift, and I also presented my conclusion that the BDS kit was superior to its primary competitor — the 4″ Superlift kit — in many respects.

This post is in large part a renunciation of that general conclusion, though many of the positives I documented in that review remain.

In short, I’m now running the Superlift kit. And here’s the simplest explanation why:

Can you see that? The key difference is most noticeable in the front: the Superlift has more, well, lift.

Measuring the Differences

How much more? Quite a bit, actually. For this experiment I took my 100% BDS lift and replaced it with an almost 100% Superlift lift (more on that “almost” in a bit). Both are marketed as 4″ lifts. The result:

• Changing nothing but the kits, I gained about 2″ lift on the front and 1 1/4″ lift on the rear.

Seriously. For a couple of 4″ lifts, that’s a rather significant percentage of difference. Measuring from center of the wheel hub to the fender lip, here’s the actual data:

• BDS Front: 21 1/8″
• Superlift Front: 23″
• BDS Rear: 22 3/16″
• Superlift Rear: 23 1/2″

Not enough for you? Here are some more pertinent details:

• BDS Loaded Spring Height: 11 1/8″
• Superlift Loaded Spring Height: 12 1/2″
• BDS Front Z-height: 2 1/2″
• Superlift Front Z-height: 4 3/4″

This is all rather staggering to me. We had always known my BDS lift was “shy” of the full 4″ lift, but we could never figure out why. My installation experience with it had been rather poor (loose screws in the most literal sense), so I had always assumed that it could be chalked up to some kind of installation error. At the time of my BDS review on this website, for instance, I was confident that with enough poking around I’d find there was a spacer missing or some other install-side screw-up that was preventing me from getting my full advertised lift. I could fix it, I thought. As time passed, however, I could find nothing that would explain it. I even went back and forth with the BDS engineers on the matter, who eventually just stopped returning my communications.

Keep in mind that what I did here was about as apples-to-apples a comparison as a fellow can manage: working with a mechanic, we took exact measurements of my vehicle with the BDS kit before we put it on the rack. Then we popped it up and over a couple of days stripped out one kit for the other and remeasured everything. Nothing else changed, and the Superlift provided 50% more lift in the front. That’s really astounding.

Here’s another fairly simple kind of comparison shot, looking at the front ends:

It was always very disturbing to me that the line of my front axles ticked upward toward the wheel with the BDS kit (like the Jeep was hunching down). You can see with the Superlift that the line now ticks downward toward the wheel (like the Jeep is rising up). (The Z-height, by the way, concerns the related angle of the lower control arms here.)

Beyond aesthetics, ride quality, and part wear, what this positive change means is that the body of my Jeep — my ground clearance, in other words — is higher with the Superlift kit. This advantage is exaggerated even more by the fact that the Superlift kit has a front crossmember design that hugs the rig much more closely. The underside of my BDS front crossmember was banged up severely, and I can’t see the same rocks hitting anything now. Plus, as is well known, the Superlift has a much broader skidplate across the front end. So this is all positive.

Not Quite All Standard Superlift

I discussed in my previous review of my BDS kit that the rear of the BDS is a truly superior design in theory. The BDS allows the wheel to travel more naturally within the confines of the wheel well, which you can see via this crude illustration comparing a stock pivot point like BDS uses (the blue circle) with a bracket-lowered pivot point like the Superlift kit uses (the red circle):

This means, essentially, that the ride of the vehicle should be more closely akin to what it was designed to have, and that as the tire is compressed into the well (as it is in off-road situations) it can travel further upward before it impacts the front of the well and begins to rub. In fact, the BDS can use a rear bumpstop that is only 2″ long, as opposed to Superlift’s 4″ bumpstop, for just this reason. Thus the BDS design has better wheel travel at compression.

In addition to a better wheel travel arc, the lack of a lowering bracket means that the BDS should have better off-road clearance in front of the rear tire — though I now know the BDS nets less ground clearance everywhere else.

Even setting aside its lack-of-lift problems, it turns out that all wasn’t roses with even the BDS rear set-up, which I had thought was near to perfect. Here’s a picture of my BDS rear, which is using the stock mounting position for the lower control arm:

As I said, this is a good thing in theory. But when we started uninstalling this kit we actually found what should be pretty obvious from the above picture: as the rear suspension flexed upward, the lower control arm (it’s the squarish black bar at the bottom, going from frame to wheel) was rotating upward and actually impacting the swaybar (the curving black bar above it). I’d lost a swaybar link bolt on Imogene Pass last year, and now I can see what probably jarred it loose. In fact, the impacts had beaten the finish off of my lower control arms, which were rusting as a result. You can see the impact point in the middle of the arm in this picture from partway through the kit swap:

The other arm was worse, but my picture of it wasn’t as clear. You get the idea, though.

Towards the Perfect Lift

Clearly, what we saw in this process of comparing kits was that the perfect kit would be a Superlift kit that had a BDS-like lower control arm setup in the rear — only a person would use a bent arm instead of a straight one.

No idiots, we made one.

Or, to be more precise, the mechanic/jack-of-all-trades I was working with made one. I’m in over my head when it comes to welding, though I really do want to learn how to do it one day. After quite a bit of fiddling with various measurements, we determined what length arm we wanted, where the bend should be, and to what degree it should be bent.

And that is exactly what I have on my vehicle now: a Superlift kit with a custom, best-of-all-worlds rear end:

In Conclusion

So that’s it.

Apples-to-apples, bolt-to-bolt, I’m recommending the Superlift kit to all those desiring a lift on their Grand Cherokee (WK) or Commander (XK). If my installation experience with the BDS had been better, I might have come to this conclusion a long time ago, but there’s nothing much I can do about that now.

Is Superlift’s current kit perfect? By no means. If I was going to make the ideal kit I would take what Superlift offers today and …

• Essentially reproduce my rear lower control arm setup.
• Cut back the front skidplate to allow better oil drainage access.
• Add cam-bolts to the front end to facilitate alignment.
• Use a better attachment system for the front skidplate (backing nuts are hard to access).

Yes, that would be most awesome indeed.

Alas, until that happens, I think this’ll do: