Quote:
Originally Posted by Msquared
The spring rate loss the OP is talking about is due to the fact that with stock rubber bushings, the inner sleeve is captured by the pivot bolt and held to the frame, while the outer shell rotates with the control arm. So when the arm moves through its intended arc, the rubber bushing has to twist, and its hysteresis adds to the wheel rate. It is accurate to say that switching to rod ends - which add no wheel rate at all - will reduce wheel rate by eliminating the rubber bushing's hysteresis.
The problem with quantifying it is that every rubber bushing in every car has different dimensions, and some rubber bushings are even partially hollowed or fluid-filled. So we can just give a blanket rate spec for each bushing. Also, I think the rate from a twisting rubber bushing would be progressive and therefore much less for the initial amount of travel than it would be near the end of suspension travel. The only good way to quantify it would be to unbolt each link and literally put a scale under it as you move the unbolted end of each link...and you'd have to do this for each end of each link.
My guess is that the added wheel is fairly low, especially in the first couple inches of suspension travel in each direction. But it's not nothing.
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I forgot that it might have been you that made the statement, too. If so - my apologies. I've read many of your posts.
Thank you for your comments. You must be onto something because I can't really find a reference for any of this, so maybe using a scale, as you've stated, might be the closest thing to me finding any good numbers. Hmm...
At least, now, if my OCD won't let this go, I have one way to try to figure this out. Thank you.