My '03 TJR has the hefty Rough Country adjustable track bar ...it's a stout, simple unit , has a good curve for clearance, and may be one of the best items they sell.
Another cool feature is (with their mount) both ends are oriented vertical, so the frame end mounts like the axle end ..and both ends accept the stock bushing. This also means it pivots with the bushing sleeve on the bolt, not at 90°, meaning a simpler connection that puts less stress on the bushing and bolt.
The downside is the factory bushings are junk, and that's really bad with 33" tires. Really bad.
Being a believer that a track bar , or control arm for that matter , is no better than the bushings , at some point I "upgraded" (so I thought) each end to Energy Suspension polyurethane 2 piece bushings with a 12mm bolt at the axle end. To some extent, it was better than the stock replacements I had in there, but marginal at best...marginal meaning I was closer to death wobble than I knew.
I put all Moog components on the front end with a ZJ tie rod and all of a sudden had death wobble from a bump. I'm like , holy cow , upgraded my way to death wobble ...here we go.
At this point I needed professional help, so I reached out to @Mr Blaine and
@Dave Kispaugh (Jeeps West) .
Blaine pointed me toward my upper control arms , and sure enough, one bushing was loose in the mount , and Dave recommended getting away from the 2 Piece bushings in that track bar, and installing Moog K-7252 bushings (this is the Moog replacement bushing for a 3/4 ton Dodge truck). You have to either sleeve the bushing or upsize the bolt, which needs to happen at the axle end any way if you run big tires. Both gave great advice.
So, the short of it is the harmonic I generated found the it's way to the weakest 2 components once I beefed up the front end ...and that was enough.
So what all is there to learn here?
2 piece Energy Suspension polyurethane bushings don't belong in a Rough Country track bar for one , because the o.d. fit is not tight enough nor is the track bar end wide enough to capture all the material . The 2 piece design alone has inherent downsides as well.
Secondly, you are dealing with a bushing that is mostly all polyurethane...harder or not , it is still more material to compress...10 percent of a 1/2" is more travel than 10 percent of 1/8 " for example.
If you hold a stock track bar bushing in your hand and the K-7252 , it is obvious from the weight there is a big difference . The K-7252 sleeve is huge, has half the rubber , which means it has to be dense, and the outer sleeve is very thick as well . It's for a 3/4 Ton ,7500lb truck, it's up for the task, big time.
Also on a big note, thanks to Blaine, I learned that a weakness can be revealed by strengthening other things ...the control arm bushing mount I knew was suspect had never given me a problem, because the system was soaking up the energy when it was more stock and had the 2 piece bushings...it simply never got all the stress. Energy may eventually dissipate, but it's going to go as far as the system can transfer the vibrational frequency til it finds the weak spot if it's a hard enough lick and nothing else gives.
A sure sign you have weak track bar bushings, prior to bump activated death wobble, is having to counter steer excessively on wavy roads ...counter steer meaning as if driving with a side wind you are fighting. If the axle is floating left and right , the tires turn the opposite way as it does because of the road friction , and you have to nudge the wheel a lot.
To wrap this up, the TJ owner who does all the work he can needs to understand his track bar and how to make it stronger, along with checking all the mount points for the suspension
occasionally.
Including your lower shock bolts , you have 34 bushings you ride on, plus your body mount bushings. These things really are suspended ...it's something to think about.
