11-05-17, 09:12 PM
(11-05-17, 08:04 PM)Fazerider link Wrote: [quote author=stet link=topic=22470.msg260372#msg260372 date=1494525319]
Shame to contradict on my first post, but the stiffness of a round cross section torsion bar (spring is a coiled torsion bar) is proportional to the fourth power of the torsion bar diameter. As a result a slight increase in diameter results in a large increase in stiffness.
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That would make the thou spring about 17% stiffer if all other variables are the same. And even if you do measure the spring rates it probably doesn't help much since the springs are different lengths and the FZ6 one looks as if it'll hit the stiffer rate a bit sooner.
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Yes the thou spring is 17% stiffer, but I recon the thou is roughly 14% longer, so the effective base rate would be about the same for both springs. As you say, it looks like the FZ6 would hit the stiffer rate sooner.
There is another aspect too: the FZ6 is the weaker (mechanically) of the two springs so I would not recommend using an FZ6 spring in a thou, although this is based on theory rather than any practical experience with the two springs.