coilover question

[prelude180]

Just a quick question about the coilovers. I was wondering do the different springs have slightly different heights while in the same coilover? As the rates increase, do the amount of coils increase? Is the metal thicker? Also is there a different shock coupled with different spring ratings on a coilover like say the D2?

[sr240mike]

If the spring rates are the same and the height adjustment is the same then the springs should compress the same amount as long as the spring is linear. When I ordered my d2's they said the shock would be revalved to match the 9/7 spring rate I ordered. I finally received the d2's after 2 months and I can't tell if they even sent the right springs with them, there's no numbers or anything. Not trying to hijack your thread but does anyone know how to tell the spring rate on the d2's? The springs are black if that helps.

[prelude180]

thanks for the info. How do they make springs have a higher spring rating? Also in if you drop the car significantly on say D2 coilovers, it has front camber plates to fix the camber. But what about the back camber? Do you only need rear upper control arms or do you need anything else. When significantly dropping in the rear is the cmaber the only thing affected or is caster, or toe-in affect to?

[AKADriver]

Springs used for coilovers come in a couple universal diameters (2.25" and 2.5" OD). Racing springs like this are available from a few different manufacturers at almost any length. If you want to change rates on a set of coilovers, you don't need to buy the spring from the manufacturer... just measure the uncompressed length of the spring and its outside diameter and order new ones from any racing spring supplier. This way often gives you more spring rate choices. Japanese manufacturers typically step their spring rates in 1 kg/mm (56 lb/in) increments. US and European manufacturers step their spring rates in 25 lb/in (0.45 kg/mm) increments.

Springs of any length can be built to almost any spring rate because of how a spring works. When you compress a spring, what you're actually doing is twisting the wire. So spring rate can be changed two ways, while keeping the free length and diameter constant:

- changing the thickness of the wire. Thinner wire twists more easily, so a spring made out of thinner wire will compress more easily. This is a geometric relationship - a spring with wire that's twice as thick will have four times the spring rate.

- changing the number of coils. If you keep the spring length the same but add more coils, if you were to "unwind" the spring, the wire would be longer. The longer the wire, the easier it is to twist. Therefore, the more coils, the easier the spring is to compress. This is a roughly linear inverse relationship - a spring with double the coils will have about half the spring rate. Anyone who has seen progressive-rate springs will understand this.. the more tightly-wound end of the spring is easier to compress.

[prelude180]

WOW, that post was incredibly helpful. :bow:

[prelude180]

does D2 or a similar company have different shocks coupled with their different spring ratings?

[prelude180]

Also I think I mis-asked my questoin above. If a manufacturer like D2 or their copycat, offers such a large range of spring ratings to choice from, do they have different shocks or different valveing to go with each rating? Basically, does each spring rating come with its own shock? Or do they expect you to adjust the shock through it's 32 levels of adjustment to find a setting that compliments the spring ratring. does this make sense?

Also I understand what camber, and toe are. But what is caster, isn't that movement on the same axis as the axle itself?

[Dustbunnie]

The D2's use the same shock for every spring that you could possibly order, so basically there's a happy match between springs and valving...I've read that they're supposedly valved to go with the 7 front/5 rears, but that's just what I read on the net, so who knows...

caster is the angle that the wheel will travel on as it's compressed...zero caster means it travels straight up...I can't remember which is positive or negative, but it means that the strut is like tipped forwards (think of a shopping cart's wheel and what points it rotates around)...it makes the wheels tend to be self-centering (again...positive or negative does this, but I can't remember which, out of the two)

[prelude180]

So if you were to say buy the D2s with the 22K spring rating (not that I have any reason to), would the shocks go out much faster becasue they are valved for the 7Ks? What does it mean to have an inverted shock design, and why is it better/ more expensive? Also I'm stil confused on your description of caster. Is it the point on the bottom of the front wheel upright that the wheel pivots with, or is it a point somewhere on the axle?