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Discussion Starter #1 (Edited)
TESTED ELISE/EXIGE LSS SPRING RATES:
Front 272 lb/in
Rear 359 lb/in


Corrected 8/11/2014

First off - I'm a nerd. No need to state the obvious. Second, I'm rarely ever content with labels on products.... So, I opted to test the spring rate of my newly arrived LSS springs. Front and rear testing complete.

1k Hz sample rate, 1.8" amplitude, 2 Hz sine wave, 10 second sample period. I didn't zero the load or LVDT readouts, so neither ranges are centered about "0".

The linearity is good & the hysteresis is minimal (as expected from a steel spring). The two springs also match within .7 lb/in, or .3%, which is excellent in my opinion.

Front LSS spring no. 1, 272.1 lb/in:


Front LSS spring no. 2, 271.4 lb/in:


Rear LSS spring no. 1, 358.9 lb/in:


Rear LSS spring no. 2, 359.6 lb/in:
 

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Holy cow, what a nerd!

You dont happen to be a nerd in Colorado do you?

Would love to watch ya do the test.
 

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Discussion Starter #5
I thought LSS fronts were supposed to be 211 and the rears 289
They have 47.5 N/mm (front) and 65 N/mm (rear) printed on them. So that would imply 271 lb/in front and 371 lb/in rear. Pretty much exactly why I wanted to test them.

Nope - not from Colorado. I live in New Mexico. Maybe you're thinking of Iain? The testing isn't very exciting to watch. I use a 2000 lb servo hydraulic actuator, a programmable controller and a 5000 lb load cell.

Iain, there's a reason I posted in the auto-x sub forum and not the suspension sub forum. ;)
 

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Ticket Magnet
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When we used to test spring rates, we had a hydraulic jack mechanism that would compress the spring against a scale. There was a ruler along the side so you could measure the weight resistance along the full travel of the spring. It was pretty simple, really and performed very well. It even worked when the electricity was out!
 

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oh, had I the tools, I'd test them, too;).

While we collectively think the springs are too soft, that's pretty freaking stiff for a stock spring on a 1900# car.


Iain
 

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Your all dorks too!
 

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Discussion Starter #10 (Edited)
LTS spring load vs. deflection plots for comparison:

Front: 235 lb/in (LSS = 15.7% stiffer)


Rear: 337 lb/in (LSS = 9.4% stiffer)
 

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While we collectively think the springs are too soft, that's pretty freaking stiff for a stock spring on a 1900# car.

Iain
Rates alone don't tell the whole story.. Nor does just the weight of the car. :)

The car needs stiffer springs!
 

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I want to share my recent experience of LSS vs non-LSS springs. My car is an '06 Elise with factory LSS springs. I've always considered the ride stiff, tolerable, but stiff. My fiance just brought home an '07 non-LSS Elise (w/factory SC).

The ride quality difference between her car and mine is considerable. Hers "rides like a Caddy" compared to mine. Where my car bounces off every joint in the freeway, bouncing the headlights up and down....her car just sucks up the bumps and you hardly feel them. Also, her car has significantly more body roll.
 

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From what I've gathered from scattered information online, I was told the Track Pack Bilsteins are 271/371 progressive, I guess I was misinformed after all.
But the 271/371 rates are consistent with your finding, although the rears ended up being more like 359lbs/in.

I, too, would have gone full-nerd on the subject given I had the right equipment(but maybe that's an excuse), so you're not alone.

I hope shock dyno plots are next up on your agenda. :)
 

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Ticket Magnet
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I believe that a progressive spring would be composed of either coils of varying diameters along their lengths (not uniform like a slinky), or of varying diameter metal stock (never seen it but have heard of it and in theory it could work)
 

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Rates alone don't tell the whole story.. Nor does just the weight of the car. :)

The car needs stiffer springs!
Yeah, I don't doubt that one bit - I like stiff springs. Just an observation, they're unusually stiff for what they are/what it is.

S2k spring rates (no idea how accurate, but looks legit):

MY00-01: 218 front / 291 rear --> fronts are 25% softer
MY02-03: 249 front / 306 rear --> fronts are 19% softer
MY04-07: 256 front / 207 rear --> fronts are 24% stiffer
MY08 CR: 375 front / 264 rear --> fronts are 42% stiffer
 

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I believe that a progressive spring would be composed of either coils of varying diameters along their lengths (not uniform like a slinky), or of varying diameter metal stock (never seen it but have heard of it and in theory it could work)
Would work, not what they do. Progressive, or "rising-rate" coil springs are made of uniform wire size, but some of the turns are wound with a closer spacing. As the spring compresses, the closer coils close completely, thus shortening the effective length of the spring.

I have not had any of these lately, but I used to have them on a daily-driver. They were Moog Cargo Coils.

Another method, similar to yours, is done by Eibach and others: Actually stack two different springs. This can give you a more-sudden change in spring rate, though.
 

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Now, of course you are going to put the stiffer ones on the driver side.



TESTED ELISE/EXIGE LSS SPRING RATES:
Front 272 lb/in
Rear 359 lb/in


Corrected 8/11/2014

First off - I'm a nerd. No need to state the obvious. Second, I'm rarely ever content with labels on products.... So, I opted to test the spring rate of my newly arrived LSS springs. Front and rear testing complete.
 

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Interesting. I had no idea the stock springs were so stiff. I guess that'd explain why it didn't feel like a 5x bump going to 550/800 like I would have expected.
 
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