Can you add in the OEM and MR rates as well?

I'm looking to upgrade my SE with bilsteins but i'm not sure if i should go with stock springs or swift sports.

 

I called up H&R and they said that they don't release spring rate specs due various factors (i.e. number of coils, diameter of coils, etc...) but they are "design to work with your oem shocks/struts" Their sport springs, model 29297-2 for the evo 9 mr, is designed for street apps.

I thought spring rates were spring rates, no? All those metrics are pointing to its build quality and characteristics that will affect the spring rates; like measuring HP?

A rather vague answer...

Don't believe me? call (360) 738-8881 or their toll free line (888) 827-8881

 

I've tired to get their information also. For the Focus, someone had to go out and test the springs.

I wish they released the data for the public.

 

Measuring spring rate is much simpler than measuring HP. Any suspension maker who won't tell you the spring rate of thier product is suspect. They perfectly well know the spring rate (or the spring rate curve, for progressive springs), and must have an ulterior motive for not telling you.

Choosing spring rates front and rear is the basic foundation of tuning your handling. Most cars have an ideal ratio of rates front-to-rear that makes for neutral balance (no understeer / oversteer). Deviating too much from this balance can be dangerous.

The Evo 8/9 likes a spring rate ratio of between 7F/8R and 6F/8R, depending on what you've done to the anti-roll bars and the diffs. I prefer the 7/8 ratio in my autocross car, because it results in less rear wheel lift on turn-in than with a stiffer rear, allowing me to put down power sooner.

Anyway, you can measure spring rate yourself pretty easily, if you take the spring out of the coilover. Just stand it up on a level floor or pavement and measure its length with and without a weight on it. For example, put a small light board on top the spring and measure the height of the board from the floor. Then have someone of known weight stand on the board on top the spring, and again measure the height. Spring rate is defined as: weight / compression-distance, and is measured in either lb/in or Kg/mm. So, for example, if your friend weighs 250 lbs and the spring gets 1 in. shorter with her standing on it, that's a 250 lb/in spring (and you need to find a thinner girlfriend :-) ).

 

don't worry i know the math behind it. it's just nice to know what the expected spring rate is prior to purchasing.

and for the correlation used, i figured both had multiple methods of measurements but in the end both are still tangible results giving some relevance to the expected performance

(i.e.) a 2.0 4 cylinder turbo makes 300 hp
(i.e.) a 6 cylinder makes 300 hp

(i.e.) spring A made of material ABC have a spring rate of 250 lb/in
(i.e.) spring B made of material DEF have a spring rate of 250 lb/in

hopefully that explains what i was trying to convey

 

Okay, I think I get what your saying now, and the answer is still that spring rate is much simpler than HP. Every engine has a different torque vs. RPM curve, and just knowing the peak HP tells you nothing about the shape of this curve. The small turbo engine makes its peak torque at a much lower RPM then then the bigger 6-cylinder and hence has a flatter power curve and more useable power for most purposes.

But ignoring progressive springs, spring rate is just a single number and that's the only important characteristic of the spring for tuning. The material, the diameter of the coils, the thickness of the wire and the spacing of the coils are all irrelevant to its effect on handling, for a given spring rate. It's really that simple.

And there aren't different definitions of spring rate, unlike with power, where it may be engine power, or power at the wheels, or may be adjusted for temperature and atmospheric pressure. Spring rate is just how much force it takes to compress the spring a given amount.

When in doubt, buy coilovers with no springs in them, and order your own springs, e.g. from Swift, which has an excellent selection that you can order by length, spring rate and outer diameter:

http://www.swiftsprings.com/file/metric.pdf

 

Why aren't Swift springs on this list?

 

List is terribly outdated.

Added Swift and GTWorx.

 

As long as you're doing some house keeping, you could update the stock spring rates. I measured a set of stock MR springs a few years back, and they are ~200f/~270r (significantly higher than the value that's been in this thread for umpteen years). Here is a link to the thread where I posted it:

https://www.evolutionm.net/forums/ev...ml#post5181441

 

I see you indicated the GTWorx as progressive. My recollection from their development is that its a linear spring rate.

 

It is as linear as possible, some progression is necessary. I'm not sure if I'd call it progressive or linear.

- Andrew

 

Ill call it linear, since thats what the design is after.

Work for you?

 

Maybe "mostly linear."

Thanks Mike for adding them.

- Andrew

 

That list is outdated.

Ohlins DFV's are not listed, but mine came with 10k and 8k springs. Mounted the 8k's in front and the 10k's in the rear. I have since gone up to a 10k/12k setup.

 

Mostly linear it is

mrfred, updated stock rates. We can edit as we go here. I have some time for it.