Spring Stiffness Spreadsheet

[snowman4us]

Cool info, but that is a huge spread on the spring rates.
Anyone have any shock info?
Compressing and rebound travel along with shock dyno.
I am concerned that some of these springs are such high rates compared to stock that the struts are outside the damping range and are being overpowered by these high spring rates. Also with drops of as much as 1.5" the struts might be bottoming out.

Hope that the manufactures who are active on this forum post up this info to justify the engineering behind the design and educate the rest of us.

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[derieuz]

Cool info, but that is a huge spread on the spring rates.
Anyone have any shock info?
Compressing and rebound travel along with shock dyno.
I am concerned that some of these springs are such high rates compared to stock that the struts are outside the damping range and are being overpowered by these high spring rates. Also with drops of as much as 1.5" the struts might be bottoming out.

Hope that the manufactures who are active on this forum post up this info to justify the engineering behind the design and educate the rest of us.

With some quick google searching, ive seen a trend that the more aggressive spring, the lower the miles it will take for a shock to go bad.

 

[BMR Tech]

That is correct, and is why we will recommend better dampers for our Handling Springs.

The Performance Springs we are going to offer, are going to work very well with OEM Dampers.

 

[snowman4us]

BMR, it is sounding like you guys have done some testing with stock shocks to optimize a spring.
Have you run the stock shocks on a dyno, and would you be willing to post up the plots if you have run the shocks? I am sure everyone would love to see the curves along with a comparison between the GT base vs GT PP shocks.
Ford states a shock upgrade on the PP over the normal GT, are the BMR springs designed to optimize the GT base or PP package shocks?

You also mention that your handling springs are suggested to be used with better dampers. Different brand shocks are valved differently as you know, so it would be nice to see what shock the spring was optimized for, as "better" damper is a blanket statement that can mean many different things to different individuals.

My intent is not to put you guys on the spot, I think this information will allow individuals to make a more educated decision when purchasing a spring and possibly swing some sales to you guys if you are able to justify your design with engineering instead of going by the seat of the pants product release which many companies seem to use when developing springs.

 

[BMR Tech]

We designed our Performance Springs around the PP Dampers.

I do have shock dyno data, but I am not able to share it at this time for several reasons.

And yes, we have been testing springs since October. This is how we have been able to spec out specific springs for various uses.

On top of that, we actually have a set of our competitors springs on our PP car as I type this. ;)

 

[snowman4us]

Would you be willing to state how much compression and rebound travel the stock shock has on the PP from the OE static ride height?

Thank you

 

[BMR Tech]

I do have that data at the office. I will gladly share it tomorrow when I have time.

I am fairly certain I have posted that on another thread somewhere, but I cannot remember which one it was.

As for my better damper comment, I basically meant aftermarket. A "better" damper will be any aftermarket version that is going to control a stiffer spring more effectively. They usually compensate in the design for lowered vehicles as well (travel range) - I should have said aftermarket, instead of better, I do apologize.

Pretty much, any aftermarket offering should work with our Handling springs. I think the valving that Koni, Bistein, etc will offer, will work well just as their stuff does on the S197 Platform.

 

[Daytona Coupe]

Kelly,
Just to throw some more work at you - I know a guy like you has also worked out the motion ratios, any chance you can share that?

 

[BMR Tech]

I have! Of course.

Off the top of my head, the rear calc was like .492ish

The front shares a similar MR to the S197, which is close to a 1:1.

 

[VTECSAUCE]

http://automotivethinker.com/suspension/linear-vs-progressive-rate-springs/

Linear springs are more predictable, and have the same rate across the whole travel, so if a spring is rated at 100 pounds per inch, every inch the spring compresses will take an additional 100 pounds of force. For a progressive spring, it is not consistent and difficult to gauge (like stated above), depending on how the coils are arranged, it could have 3 inches of travel rated at the lower rate and then once the lower rate springs are fully compressed, the higher rates will kick in. The also you can begin to compress the higher rate portions of the spring while loading up the lower rate portions depending on the rates

In the short, linear springs will give you a harsher ride as they will always be stiffer but they are far more predictable while a progressive spring will give you the stiffness when you are loading the spring up and give you a less harsh ride when you are just hitting bumps, the downside to progressive rates is predictability for performance drivers based on the stiffness. Considering all of the above progressive rate springs start out stiffer than our cars, it's safe to say that they still will be just as predictable or more predictable than our OEM springs.

In essence, this is what I was attempting to say. My brain doesn't have the greatest functionality on night shift it seems. Oh well

 

[snowman4us]

I do have that data at the office. I will gladly share it tomorrow when I have time.

Did you have a chance to take a look for that info?

Thank you

 

[mikeyjobu]

All of this is enough to keep me out of any suspension mods until there are dampers matched to the springs, and some others have sorted it all out. In the early shootout against the 1LE, Randy Pobst pointed out that the car would likely benefit from better dampers and "maybe a little spring" -- this indicates to me that persons looking to make their daily driver perform better at the track, mod for mod, the better option may be to wait for better dampers...

 

[Grimace427]

this indicates to me that persons looking to make their daily driver perform better at the track, mod for mod, the better option may be to wait for better dampers...

This has been true for a while. Bang for the buck, dampers are #1 IMO. Adjustable would be preferable for dual purpose street/track, but a controlled non-adjustable damper is always a nice improvement not only in track performance but ride quality as well. Dampers reduce floatiness and harshness when hitting large bumps.

 

[Schu]

No Hypercoil application? for shame.

I would have preferred to have seen the information in weights and make my choices that way instead of % of stiffness differences, that is unusable.

is there a reference link for OEM Spring size in terms of ID/OD and Length? I can not seem to find that anywhere. armed with that information, I can just get my own springs.

 

[BobbyV]

Anyone know what type the stock PP springs are? Linear or progressive?

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