Seems to be a pattern here. I understand that control arm length doesn't matter, just put the axle where it needs to be to clear the track bar. One thing in common in most of the track bar threads is it usually is discussed in lifts under 2.5" as at that height max up travel is very important. It doesn't seem to be much of a discussed issue at or above 3.5" lift height. That is because either people are running 3" or more bump stop to keep tires out of fenders or they just are not aware of the issue or don't care, because they flexed it on a curb at the mall and it was OK.
Most if not all lower lifts seem to clear the track bar no problem with stock length lower control arms, with stock style diff cover. I have found a few cases of guys with 3.5" or taller lifts who run high line fenders, we are looking for more up travel than a guy with stock fenders. So we run into the TB-diff cover interference issue. Lower lift rigs can set LCA to factory length or run stock LCA and clear TBs. So when a guy with a 3.5" lift who has TB diff cover contact sets the LCAs to factory length or as short as they will adjust and still has contact, what are they to do? Why doesn't it work? In reality it does not matter, just adjust them till you get what your jeep needs. Nobody is going to tell you your jeep wheel base is 1" short.
Unfortunately I am a "why" type of guy. I have been somewhat intrigued by this for some dumb reason. Why is it that a short lift will clear the track bar and the taller lift wont with the same lower control arm length. The real measurement/difference here is from frame side LCA bolt to axle center line. This length gets longer as the pinion angle is adjusted up. Taller lifts obviously need pinion angle correction to eliminate drive line vibrations. When we do that we lean the top of the axle forward. What also happens as the pinion rotates up the lower axle mounts raise in relation to axle center line, which increases the distance from the axle center line to frame side bolt. So it may be needed to adjust LCAs shorter than stock length to get to the magical axle location where everything will fit at short bump stop lengths.
My Rubicon Express lower control arms will only shorten to 15.75". I will have to cut them down to get enough adjustment.
Hopefully that make sense and helps somebody.
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