04-03-2020, 06:46 PM | #3767 | |
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Thanks for the response, Andrew. I had a feeling that was the case and I believe I had seen you write that before but wanted to confirm. It makes complete sense. |
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04-05-2020, 07:29 PM | #3768 |
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Did some searching and couldn't really find any concise answer, so here it goes.
^^With LCAs like these (SPL) and others with multiple mounting points for the shock, moving more inboard and outboard, would you effectively be able to alter the motion ratio of the rear by bolting the shock bottom to different locations on the arm? Meaning, if I bolt the shock to the most inward position, the value decreases, and moving outward causes the value to increase? If so, what kind of effects would one expect in terms of handling if everything else remained the same on the vehicle? And how much of a change would there actually be in the effective spring rate between those slots? Would it be changing the spring rate by like .5kg/mm each, or more like .05kg/mm each lol
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04-05-2020, 08:14 PM | #3769 | |
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04-05-2020, 10:15 PM | #3770 | |
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I did MR = A/B though. A- Overall LCA length (450mm) If stock MR is ~0.75, then factory shock mount is at 337.5mm from the center point. If the holes are ~25mm apart, that gives a range of 312.5mm to 362.5mm. So 312.5/450 = .694 And 362.5/450 = .805 That means that (rough estimation) the outer most hole would yield an MR of ~80% and the inner most hole would yield an MR of ~69%. So a 6k spring can effectively be a 4.8k, 4.5k, and 4.14k with those numbers. Of course, that's all estimated. But those numbers can also vary with alignment changes, as the LCA with change in overall length to decrease or increase rear camber. However, the differences between each hole should remain the same, meaning roughly .3k/mm or roughly 17lbs/in in effective spring rate between each one. Cool. That answers one part of my question then haha. Now I'm curious how that would impact the handling of the vehicle by changing from one spot to the next.
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04-05-2020, 10:29 PM | #3771 | |
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04-06-2020, 12:11 AM | #3772 |
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Lol nah. I can do a little bit of calculating. But I trust the suspension experts more than myself doing some quick math on the interwebz for estimation purposes.
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04-06-2020, 12:13 AM | #3773 | |
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Changing the mounting point would change the dynamic response, but it shouldn't behave too different from reducing or increasing spring rates at the same mounting points considering how little the change is. That's all speculation tho. I've experimented with different pick-ups from damper and hubcarriers using various different brands of LCA's, but not enough to answer your question. I made fairly large changes, not small ones.
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04-06-2020, 09:52 AM | #3774 |
Multiply spring rate by the square of the motion ratio, not just the motion ratio.
https://www.instagram.com/p/B3cDzqOD..._web_copy_link You're almost there with the math. Changing the rear shock mounting point to change the motion ratio will change your wheel rate. Compare it to a swaybar change but remember it also affects ride, not just roll. - Andrew |
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04-06-2020, 07:45 PM | #3775 | |
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Very interesting. Thanks a bunch for the help! I LOVE learning these little nuances of suspension workings and stuff. I don’t know why but I find it to be one of the most interesting things regarding vehicles and modifying them/setting them up.
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04-06-2020, 08:48 PM | #3776 |
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Another thing to consider with the different pickups is changes to the amount of wheel travel and ride height change. This is the main reason why i tried out the different pickups. the further inboard you mount the less damper stroke required for a given amount of wheel travel aside from the change to the motion ratio.
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04-19-2020, 06:00 PM | #3777 |
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I've been running TRD springs for a while now and I want to upgrade to BC coilovers. I want moderately more stiffness but I'm so hesitant to make drastic changes in the overall engineering so I'm thinking 5k front and 8k for the rear to simulate the OEM FR-S 2.3k and 3.8k rates. Anything wrong with this idea of matching the spring rates F/R? Thanks
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04-22-2020, 07:41 AM | #3778 |
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Hi guys. (track car only) How important is it that caster is the same on both sides? I understand caster and what it does but I got my car back from being aligned and noticed it different on both sides. I do not currently have adjustable caster. I have OEM front control arms with Whiteline anti-dive and caster bushings.
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04-22-2020, 08:35 AM | #3779 |
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I never cared much about caster evenness. Imho it allows even greater disparity then camber, before "detectable by average butt dyno". I usually care more about getting camber even, and to even much greater extent - toe.
Of course, CSG/RCE guys will now better, as what i wrote is from my subjective feel, with me having rather imprecise calibrated butt dyno [tm] . But for me it was so, that toe amount and unevenness by +/- 0.05dg was relatively easy to feel in handling, i guess camber changes like 0.5deg will start to be noticeable in right vs left turns, and i always left caster as is, whichever values it had. |
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04-22-2020, 09:09 AM | #3780 | |
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- Andrew |
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