James R.

rate springs. I whipped out the Eibachs just to compare them against the springs that came with my Koni Coil Overs when I noticed that the Koni springs are quite clearly a progressive design while the Eibach are clearly linear rate springs.

You can tell this by a number of ways...firstly the most obvious is that the spacing between adjacent coils is constant on the Eibach while the Koni's are clearly progressive aka the spacing is not constant...those coils which are closer together comprise the softer portion of the spring rate...while more distant ones are the stiffer portion of the spring rate.

The other way you can create a progressive rate spring...the, "right" way to do it by the book would be to draw tapered wire and then wind that into a spring. If this doesn't make sense to you just think about the tapered spring diameter like you would the diameter of a sway bar...the stiffness of given portion of the spring would be proportional to the 3rd or 4th (can't remember I'm and EE not an ME) power of the diameter...and would vary along the lenght of the spring. I don't think you'd find anything like this on a street car because it would be both complicated and expensive to fabricate. Anyhow as a reality check I measured the diameter of the Koni and Eibach spring wire just for kicks in case one was done the, "right" way...the Koni Front Spring wires are 0.553" and the Eibach are 0.551" the Koni Rears are 0.456" and the Eibach are 0.481" all these measurements are uniform across the spring...so any progressive behavior would have to come from coil spacing...which pretty much proves that the Eibach springs are a non-progressive design.

Now which is better or worse who knows...I know progressive springs have become rather popular...but maybe the linear rate explains why so many people complain the Eibach spring feels too soft. As for variable diameter...that's not totally necessary...just adjusting the winding spacings works well enough which is probably why it's the preferred technique...cheap and effective.

Here's some pics...see for yourself. I'm not buying any crap about heat treatment for progressive rate...I don't think that's how it would be done...to inconsistent. Anyhow judge for yourselves...comments?

Regards,

James R.

2001 A4 1.8TQMSXP (Koni Coil-Overs, Neuspeed 19mm Rear Anti-Sway, StopTech A4 Brake System, SS Brake Lines, Pagid Performance Friction (soon), Oettinger Pedal Set + Dead, Oettinger RE's 17x8, Yoko AVS Sports 225/45/R17, European Xenon Housings, Bailey BPV & RS4 Grill)

<img src="http://pictureposter.audiworld.com/227/frontsprings.jpg">
<img src="http://pictureposter.audiworld.com/227/rearsprings.jpg">

Johnny Bravo

It would be great to discuss things again. Not too much time at the last conejo drive.

BTW, your posts, have a an uncommon balance of Ethos, Pathos and Logos, with a slight emphasis on logos, but that totally acceptable since you have an engineering background.

I was just looking over one of my old papers on argumentation and I was inspired to write my analysis.

Regards,
Jonathan C

Lazyg

I had no idea about the two designs except for thier existence.

Thank you for the post.

Are you installing either the Koni coilovers or the Eiback Springs?

James R.

The Konis are going on the car...the Pro-Kits go back tomorrow...

James R.

I'm glad you appreciate my style...I just call em' like I see em. I could be wrong...the Eibach box says Progressive Characteristics but that doesn't mean the spring is really progressive...there's no truth in advertising these days ;-0 I suppose they'd have to be progressive to some extent...like when the coils are in bind the spring rate goes up heheheheheh like a lot. Seriously though if I had to bet a nut or something I'd stick to the linear claim...everything that I've seen seems to support that assertion.

As for the KK run...do you mean Van Nuys? That's kinda a trek for a KK run...they do those out here in OC but I don't like the fact that silly place is so crowded you're lucky if you can find a bad parking space...let alone a good one. Call me ****...but hey there's not a ding on my car, it pays to be **** sometimes.

Yeah we didn't get in much time at the last drive...bummer, I'm sure we'll hook up. Didn't you say you live down this way anyhow? If so maybe we could hook up with Frank and Cheng and Marc and all those guys...we had dinner last Saturday at Shabu Shabu it was a pretty good time...if you sit next to me we can talk about $hit (the place is laid out funny...so you have to be next to someone...you can't sit across from each other...not too good for big conversations)

Regards,

James R.

2001 A4 1.8TQMSXP (Koni Coil-Overs, Neuspeed 19mm Rear Anti-Sway, StopTech A4 Brake System, SS Brake Lines, Pagid Performance Friction (soon), Oettinger Pedal Set + Dead, Oettinger RE's 17x8, Yoko AVS Sports 225/45/R17, European Xenon Housings, Bailey BPV & RS4 Grill)

RKA

Worn spring genereally sag, but what else?

The reason I ask, is that I posted a month or two ago that my Eibach's seem to be riding a bit funny. My observation is that there is a transitioning between a softer rate and a higher rate on the spring. I've got Biltstein shocks, but having driven in and H&R/Bilstein equipped car, I noticed a very different ride (more linear). If James' thoughts are correct, the only explanation left seems to be worn springs or I've got a screw loose! I'm dismissing the later for now. Anybody?

WClark

The Audi/Eibach sport spring is specified as a linear spring but the real proof of exactly the same or somewhat different would be the part numbers.

I agree with your opinion on variable tempering. It is probably possible but at these prices it isnt going to happen. Anyway, photos of other Eibach progressive springs look just like the Koni.

James, can you collect those Eibach part numbers? I will look up the numbers for the "Eurosport" tonite.

WClark

Oh, a quality coil spring hardly ever wears out, but with some of the disparity I have read between pro-kit owners in terms of settling and ride firmness there may well be some significant consistency issues with the Eibach pro-kit. This would likely be at the heat treating step, but I guess they could be getting inconsistent wire alloy. An improperly (insufficiently) heat treated spring would tend to lose its initial characteristics and that would make them feel soft or worn out.

RKA

1.5 fingers. Good thoughts, but it's not the bump stops...that's a rather *abrupt* feeling.

James R.

heavy compression.

Regards,

James R.

2001 A4 1.8TQMSXP (Koni Coil Overs, StopTech A4 Brakes, SS Brake Lines, Pagid Performance Friction, Oettinger Pedals, Oettinger RE's 17x8 Yoko 225/45/R17, Euro Xenon Housings, Bailey BPV and RS4 Grille)