technical? Dual spring coil-overs?
 

ok my question here arises after a little debate. I dunno if this could be a "TQW" or what, but I'm wondering why some of the coil over systems use a dual spring setup.

Specifially we installed a set of Tein HA's on a FC awhile ago and it used a helper spring in series with the main spring. The helper spring seemed to have a significantly lesser spring rate.

What's the function of this? I figure this would perform more like a typical "progressive" spring would and not be nearly as benefiial as a true single spring coil over system.. Does this spring serve the purpose of softening the ride, or does it serve a function related to the cornerweighting/ride height adjustment by serving as a preloading device?


Anyone?

The helper springs I know of are used to keep the coil spring from rattling in the perches when the suspension is at full droop. It basically does nothing for the actual handling.

so is the helper spring fully compressed when the suspension is loaded with only the weight of the car?

That is my understanding.

I'm not so sure that is true. I'm not saying that you are wrong or that I know any better. It just seems a bit odd that companies would go through the trouble of designing a helper spring just to be compressed fully when the car is completely on the ground.

I would think that the helper spring would be used for cases when you need less resistance that the main spring strength. I would think it would be similar to a progressive rate spring in concept except that you would have to set spring rates instead of a progressive rate. Just my two cents. Again I'm not saying I'm right, but it seems to make more sense to me.

- Cody

I don't know personally of any other applications but when some aftermarket coil springs are too short and the car is jacked up the springs leave the perches. The helpers are there to provide enough force to hold the "main" coil spring in place until the car settles back on its wheels.

I could be wrong about helper springs but having two discrete spring rates is positively an awful idea. A progressive spring essentially has an increasing resistance where what you describe would have a softer rate until the soft spring collapsed into coil bind and then instantly transform to a higher rate. At best this will wildly unsettle the chassis, at worst it would put you in the weeds.

as DamonB sez, helper springs hold the main springs in place during full droop. it helps "index" the springs in its corner-weighed position.

i seem to recall, tho, that there is a difference between a tender spring and a helper spring.

I did some research and apparently DamonB is right. I could have sworn that wasn't the purpose of the springs, but mulitple sources are telling me otherwise. Sorry if I caused any confusion.

- Cody

A helper spring has a spring rate around 25# and the tender spring is above a 100# last I checked with Ground Control.

Rishie

Helper spring should be fully compressed when suspension is loaded. Then under full expansion of the damper the helper spring allows the main spring to maintain it's proper position in the spring seats while the damper is compressing.

I have helper springs on my coilover setup. They're pretty close to zero rate-- you can pinch them closed with your fingers. And yes, all they do is keep the main spring indexed (i.e., concentric with the shock body) when the suspension drops farther than the free length of the main spring.

Tender springs are available with linear rates and with progressive rates. So as you can imagine, the number of combinations is large. Want to see what's available? Take a look at Truechoice's catalog-- and that's just for Eibach springs:

http://www.truechoice.com

They have a .pdf version of their catalog online. Skip the "Pro-Kit" lowering springs and go straight to the "ERS" racing springs (page 28 as of the date of this post).