I know on Fox rear shock springs, the first number is the "weight" of the spring and the second number is total compressible length. So, if you've got a 2.34" spring on a 2" stroke shock, you could get away with 0.34" of preload.
However, I've got a titanium spring and I check when I bought it, that the 2" written on the spring, refers to the shock it was designed for, not the total compressible length. Well, I want to try some preload on it but I'm wondering how much I can play with. Is it as simple as measuring the free space between all the active coils or is it more complex?
Is it a safe assumption that so long as the adjacent coils don't touch when I bottom the shock, then all will be okay?
No one ever designed a spring?
Just measure all the free space between the coils. the limit to how far you can compress a spring is when it becomes coilbound - ie no spaces
Thanks, that was the logic I was going by but I was just wondering if there was a region before that where I'd be doing any damage.
doubt it, that should be part of the original design in that the point where the metal is going to be deformed ( cant remember the proper name ) is beyond the point where the spring itself becomes coil-bound. I do wonder about the springs with really wide spacing though.
I wonder the same fisha. With a low coil number, there's a greater amount of torsion throughout the spring before it gets coil bound. In theory, it might be enough to go beyond the elastic limit.
I'm no expert, but I don't think you should be preloading the spring that far.
TF Tuned says -
"On rear shocks, the spring preload collar is infinitely adjustable (with a little help from some pipegrips!) so in theory you could get the ending rate you want. The only problem here is the limited space for the spring. As you screw the preload collar down to compress the spring, the gaps between the coils become smaller. These gaps must add up in total to a value higher than that of the shock stroke. Ideally they should be 10% greater otherwise premature failure of the spring will occur. This is why all coil-over shocks have a maximum amount of allowable preload. This amount is usually between 2-8 turns and is counted from the moment the spring collar contacts the spring and begins to compress it."
I wasn't planning a huge amount but the DNX I've got always feels like it settles too far into the stroke. Interesting that Tim says sum of the gaps minus 10%
you don't want to risk bottoming out the spring at all... so i reckon your 2" stroke spring is too short for your 2" stroke shock, let alone any pre-load
but that's the point, on this spring, I was told the 2" designation refers to the shock it was designed for, not the total compressible length (like it would be on a fox spring). The proof of this is that the free length of the next longer spring is too big for the shock.