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Originally posted by budojeepr 02-18-2012 08:58 AM
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Originally Posted by Resbum
Here's what really happened when I put the track bars on. As I said, I originally set the rear axle to droop 8 3/8" of shock extension with all the operating weight hanging from it(tires/rims). After I mounted the track bars the axle only droops 7 3/4" with all its weight hanging on it. It takes my fat rear laying over the wheel to get it to extent to its original resting place. So something is going on to limit articulation.
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First off, I have HUGE respect for your fab skills and the way you're going about building and sharing your thoughts and details on the build. Second, your retirement plans nearly drive me crazy with envy.
I had the same concerns as tgreening about the articulation when I saw the pic in this post.
You're trying to limit axle wrap as a result of all that torque, right? It's a good design for that. However...
Ignoring the effects of the shackle at the back end, the front shackle -> axle -> frame mount of track bar make a triangle with fixed leg lengths. Any movement of the axle up or down, whether it's both wheels or just one, means something has to bend. Luckily, it's the spring, for most of the available travel. Once the spring rate exceeds whatever is the weakest link in the track bar or its mounting on the axle or frame, you'll break the track bar somewhere. If the spring rate is always lower than the weakest link, sooner or later you'll fatigue the spring somewhere and it'll break.
This is why most track bars have extensible arms - so the geometry can change as the axle moves up or down.
Here's a suggestion: You can mount the front end of each torque bar on its own shackle. The movement of the shackle should be enough to keep things from breaking, and it won't hurt the anti-wrap effects of the track bar.
My experience (as opposed to theory) with this is limited to a single Rubicon Trail run where my buddy's torque bar (that's what he called it) did not have any extension built in, and it busted its frame mount off. That left him with severe axle wrap and the mount on the axle would bang on his fuel tank with every bump or touch of the accelerator.
We ended up running his winch cable down under the front bumper, all the way back to the axle mount, then cinching it down. It really compressed his front springs, but controlled the rear axle. That's when I got the idea of making an axle wrap control system using a spring-tensioned cable. Of course that would only work under forward torque...
Thanks for listening (talk about long-winded!!
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budojeepr