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I've read numerous vague mumblings about how to set the rear adjustable arms. So, I started playing with lengths yesterday on my S13. I did find some possible solutions, but more questions are arising. The goal is to get the most forward grip I can within reason.
There are 2 debates here: traction arm usage and anti-squat.
Traction Arm:
I've got the 3 common rear adjustable arms, with the traction arm staying the stock length (ruca slightly longer, toe slightly shorter). Now I'm looking at the angle of the mounting tabs and spindle mounts and they don't point the same direction as the arm. With the arm lengths like this the spindle is rotated forward. This is probably causing a ton of bind on the non-spherical end, which is one reason I think I can't put power down. So I extended the traction rod 1/4" and shorten the ruca 1/8" to keep the same camber. Now the arms are at a better angle with respect to their mounts and there's less bind.
So the question is, did rotating the spindle back do anything geometry-wise (besides change the angle of the toe arm, which I don't care about)? This lessens bind, but why do I hear all the drifters say that shortening the traction arm gets you better exit grip/speed? Are there anti-squat considerations at the spindle that are unrelated to the pickup points on the subframe? If I shortened that arm, that would increase the bind, but a set of sphericals on the spindle side would fix that. What is the correct line of thought for the most traction?
Leading into anti-squat, S13's have bucket fulls. I've got a few pics of s13 and S14 subframes and the difference in anti-squat based on their pickup points is huge. So what can I do to reduce it? From what I can tell, most of the difference is in the location of the front lower a-arm mount. But you can't just move that mount because the rear-most mount will have to rotate to keep the axis of rotation in line. Major PITA. Or, I heard of tilting the subframe to rotate the instant center down, which sounds like it would work. Thoughts? I'm initially considering spacing the front subframe mounts down 1/2". Does anyone have any rough idea or calcs/sims of the S13 anti-squat percentage and/or IC location?
This is basically the only place that could discuss this subject. I feel like if I post this question/topic anywhere else the responses will be filled with "sick drift", "WAT", or both. Please chime in!
There are 2 debates here: traction arm usage and anti-squat.
Traction Arm:
I've got the 3 common rear adjustable arms, with the traction arm staying the stock length (ruca slightly longer, toe slightly shorter). Now I'm looking at the angle of the mounting tabs and spindle mounts and they don't point the same direction as the arm. With the arm lengths like this the spindle is rotated forward. This is probably causing a ton of bind on the non-spherical end, which is one reason I think I can't put power down. So I extended the traction rod 1/4" and shorten the ruca 1/8" to keep the same camber. Now the arms are at a better angle with respect to their mounts and there's less bind.
So the question is, did rotating the spindle back do anything geometry-wise (besides change the angle of the toe arm, which I don't care about)? This lessens bind, but why do I hear all the drifters say that shortening the traction arm gets you better exit grip/speed? Are there anti-squat considerations at the spindle that are unrelated to the pickup points on the subframe? If I shortened that arm, that would increase the bind, but a set of sphericals on the spindle side would fix that. What is the correct line of thought for the most traction?
Leading into anti-squat, S13's have bucket fulls. I've got a few pics of s13 and S14 subframes and the difference in anti-squat based on their pickup points is huge. So what can I do to reduce it? From what I can tell, most of the difference is in the location of the front lower a-arm mount. But you can't just move that mount because the rear-most mount will have to rotate to keep the axis of rotation in line. Major PITA. Or, I heard of tilting the subframe to rotate the instant center down, which sounds like it would work. Thoughts? I'm initially considering spacing the front subframe mounts down 1/2". Does anyone have any rough idea or calcs/sims of the S13 anti-squat percentage and/or IC location?
This is basically the only place that could discuss this subject. I feel like if I post this question/topic anywhere else the responses will be filled with "sick drift", "WAT", or both. Please chime in!
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