Spring rate help?

wstar

Yeah... so just thinking of the rear bar as extra spring rate, I started looking that. I don't know the rear motion ratios yet (for the shock or the bar), but nevermind that factor for the moment, it's probably somewhere around 0.8 or something, -ish.

So, the Hotchkis rear bar has a mfg-spec bar spring rate of 930 lbs/in at it's weakest setting (where I've had it for a while). Assuming the bar's motion ratio at 0.8 that would be ~600 (rate times motion ratio squared), and then I assume I divide that in half for the contribution to spring rate in each rear corner. So this means that the bar is contributing 300 lbs/in to my overall spring rate in each rear corner.

Let's ignore that I wanted to up my spring rates in general, and just focus on the idea of removing the bar and leaving the total spring rate alone, in theory...

So... if I just wanted to pull the bar to get rid of its side-to-side affects and leave my overall spring-rate as is, I'd have to bump my rear springs from ~500 to ~800, is what this sounds like to me. That sounds like a bigger jump than I would have expected, as it puts the rear springs significantly stiffer than the current front springs (which are 650 springs, and then if you toss in the 1970 lb/in front sway contribution it's effectively ~1280). It seems a little odd that just to remove the rear bar and cancel out that effect on rate, I'd be moving my rear springs from 150 less than the fronts to 150 more than the fronts - I didn't think it was worth that much.

Is this a sane line of thinking? Do those numbers make basic sense, aside from the totally fake 0.8 bar motion ratio? (I can fix the math for that later after I measure and get real numbers, but still, the general idea isn't going to change a lot). Or am I thinking about this wrong?

EDIT: in converting bar rate to "virtual spring rate", I think I left out also converting back through the motion ratio of the shock absorber which would change things further. But I think, if anything, that would make the +300 lbs/in value slightly larger anyways, so it doesn't really change the overall point.

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