Maximum Articulation, Useful Flex,
and the Curri Anti-rock
Often in discussions and various threads here on Jeepforum.com there are quesions of a good swaybar disconnect system or methods to develop the maximum flexibility out of the TJ's suspension system. Invariably, someone in these threads will mention the Anti-rock offroad swaybar which is then followed by questions about what is it, how does it work, and which develops "more flex." This post is an attempt to explain the idea that there is a difference between "Maximum Articulation" and "Useful Flex" as it pertains to offroad situations and how this relates to the Anti-rock and typical quick-disconnect systems.
I will tell you right off the bat that you will develop more "maximum flex" with any of the quick disconnets than you will with the Anti-rock. But how useful will that maximum flex be? Bear with me . . .
There are some Jeepers that hold the contention that all flex is not created equal. That there is "maximum flex" and there is "useful flex." Maximum flex or articulation is just what it sounds like. Just how much you can completely flex out your particular suspension setup. Max flex will give great RTI numbers and really great pix of Jeeps with tires high in the air and people will say "holy snot, look at that." The quick disconnects are great with developing maximum flex since they completely disconnect the swaybar from the axle.
Impressive, but how much effective force is on
the tire if the spring unseats from the perch?
Sometimes you'll see pictures of Jeeps so flexed out that the springs actually have no load on them and in fact may drop down from the upper spring perch. This is were we get into the idea of "useful flex." When a tire can droop so much that the spring unseats there isn't much weight on the tire. Without the weight there won't be much taction from the drooped tire. In this situation one has to ask what is the practical difference between this and having a tire lifted in the air from a traction stand point?
So the idea of "useful flex" is introduced. And that is the point at which you can flex out and still get power down to the ground with enough traction. Unfortunately, this is much more difficult to pinpoint because it will depend on many factors such as ground surface conditions, tires, traction aiding devices, specific suspension setup, load distribution, and perhaps other factors. John Currie, who's won many rock-crawling competitions and has a good reputation with the community for thoughtful designs and solutions, approaches the flex issue from the "useful flex" stand point with the Anti-rock.
The Anti-rock is an anti-swaybar specifically design for off-road driving and offroad conditions. Currie carefully engineered the swaybar to balance flexibility with chassis control. It works with the rear swaybar and keeps both front and rear swaybars connected at all times to evenly distribute forces between the front and rear axles aiding traction by keeping the weight on the tires. While much softer than the stock bar the Anti-rock also helps control body sway and lean off-road making side-slope and off-camber situations much less trecherous to negotiate.
I was surprised at the difference in off-road ride after the Anti-rock installation. The Tj felt like it just melted over the terrain. When I'd approach holes, ruts, and drop offs I would expect the TJ to shift and sway toward the depression. Not so. The tire would drop into the hole in a controled way and the chassis remained surprisingly level, balanced between front and rear axles. And the traction difference is noticable, too, especially since I have open diff's at each end. I met guys on the trail who said "oh you'll definitely need a locker to get up that hill, if you have problems, just wait for us." But the TJ would just scramble right up with no hint of any traction problems.
Besides the handling benefits there is also the ease of use. Once the Anti-rock is set up you just leave it alone. The only reason to stop at the trail head is to air-down tires. . . otherwise just roll onto the trail and roll off. No pulling pins or tying the swaybar out of the way. Likewise, when you're coming off the trail you don't have to get under a muddy Jeep and hook things back up in the rain and muck or whatever you just wheeled through. No rocking the Jeep back and forth to line-up pin holes or anything. It simply works very transparently and you forget it's on there.
Click to enlarge: The Anti-rock
installed on author's BB lifted TJ.
No pins to realign or discos
to fuss with
Despite the added control, the Anti-rock does allow a surprising amount of articulation. In one rockcrawler.com
article the author quantifies the difference between fully disconnecting the swaybar and running the Anti-rock:
- 33.25" fully disconnected (20* RTI = 1050)
- 32.00" loosest Anti-rock setting (20* RTI = 1011)
- 31.25" firmest Anti-rock setting (20* RTI = 987)
As you can see, the "maximum articulation" is developed by fully disco'ing the swaybar but the Anti-rock still allows for significant flex while providing the handling benefits. Even at the firmest setting the you only give up 6% of your total flex for all the benefit. And at the looses setting? Less than 4%
The Anti-rock isn't cheap at nearly $300. However, if anyone is considering the $100 JKS or Teraflex quick discos then they owe it to themselves to look into the Anti-rock. Honestly, after runnning with this mod for the last 6 months I would highly recommend it to anyone as it's one of my favorite mods. Especially since you can keep it with your TJ if you upgrade suspension systems and axles.
Review & Install on a 2" BB Lifted TJ
General Anti-rock Review & Install Pictures
Another Installation Review
Even Stu Olsen Installed One
Rockcrawler.com Reviews the Anti-rock Before/after articulation measurements at end of article