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Old 07-12-2013, 05:46 PM   #1
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H&R spring rates vs RoW M030

Hi guys

I may have asked this before, but does anyone know how the H&R spring rates for the 986 compare with RoW M030?

I managed to pick up a set of H&R springs for mega cheap and I already have an RoW M030 kit hanging around and going by a very rough measurement using a tape measure and eyeball, it looks like the coil is about 1mm wider on the M030 spring (didn't have any callipers handy), which is not what I was expecting.



I want the car lower than M030, but I definitely don't want softer springs. Was actually hoping for a bit harder.

If the H&R coils are indeed a little thinner, does this more or less guarantee it's softer? Is coil thickness pretty much the be-all and end all?

I also happen to have a left over custom made spring from my old BMW track day car and the comparison is quite amusing. The coil is miles thicker than either Porsche spring (and it's only a 450lb spring, which isn't that insane) and you can't bend it a mm by hand. I can squeeze the H&R spring and get quite a bit of deflection!

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Old 07-12-2013, 07:00 PM   #2
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170 & 208 m030 *
180 & 190 h&r *

These are the "soft part" of the progressive springs .. And the ride will also be determinedly the roll bars on the m030 kit

The only way a boxster will/should see anywhere near 500lb is on track-only car


Although the eibach set-up seems more favorable than the h&r for what you want , and can still be bought in Europe,
You should have a serious look at the vogtland lowering springs
Little known German company that have been around for years that often get lumped-in with the "economy" lowering spring crowd as they don't advertise as aggressively as eibachs and h&r








*

I am researching these figures and still don't have a definitive figure. although the info is out there on most aftermarket German equipment due to the TUV laws .







.

Last edited by Ian c; 07-12-2013 at 07:05 PM.
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Old 07-13-2013, 07:21 AM   #3
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Thanks for that. God, very soft, which is really what I thought - you can tell they're very soft just looking at them.

I ran 650lb front, 550lb rear on my old BMW E36 2.8l coupe - that 450lb spring was just a left over spare, I had several sets. It was mostly a road car that I also tracked. Was obviously very firm, but I enjoyed it!

You wouldn't need springs that stiff on a Box as its centre of gravity is a fair bit lower. But those rates you quoted are very very soft. I suspect M030 springs are only a little firmer than the standard springs.

That said, as you say, that the soft part of the progressive spring, but looking at the springs I have in hand, I very much doubt they're more than 250lb at any point in the range.

Anyway, when you say still researching, are you not sure the numbers are accurate? The difference between the two kits is utterly negligible if your numbers are right...
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Old 07-13-2013, 07:49 AM   #4
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I believe they're accurate numbers but I'm still confirming ...

Spring rate isn't the only thing changed with the m030 kit though .
The differences in the height also effects car balance front/rear .... Porsche should have carried on using height-adjustable as stock .
And the arb differences also change the driving characteristics , and on top of that it as different alignment numbers ..

If I where you I'd stick with the softer springs and stiffer arbs


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Last edited by Ian c; 07-13-2013 at 08:06 AM.
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Old 07-13-2013, 08:26 AM   #5
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Boxster Spec race cars typically run 450/500 springs. I personally think this is too much spring resulting in excess wheel spin on corner exit. Not everyone agrees.

Try 450/500 and see what you think.
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Old 07-13-2013, 09:02 AM   #6
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Neither H&R or Eibach publish their spring rates. However, if contacted, Eibach will share their information. Based on my previous inquiry with Eibach, they indicated that their spring rates for the 986 boxster are 450/500. With that said, I suspect that the H&R's are in all good likelihood the same.
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Old 07-13-2013, 09:06 AM   #7
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Neither H&R or Eibach publish their spring rates. However, if contacted, Eibach will share their information. Based on my previous inquiry with Eibach, they indicated that their spring rates for the 986 boxster are 450/500. With that said, I suspect that the H&R's are in all good likelihood the same.
Johnny, honestly, there's zero chance that Eibach lowering springs are that stiff.
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Last edited by pothole; 07-13-2013 at 09:12 AM.
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Old 07-13-2013, 09:07 AM   #8
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Boxster Spec race cars typically run 450/500 springs. I personally think this is too much spring resulting in excess wheel spin on corner exit. Not everyone agrees.

Try 450/500 and see what you think.
I'm using M030 struts, so no chance of that, both because the dampers won't be able to control the springs and because I have no control over ride height.
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Old 07-13-2013, 09:41 AM   #9
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If the H&R coils are indeed a little thinner, does this more or less guarantee it's softer? Is coil thickness pretty much the be-all and end all?
The coil spring rate is simply characterized by the thickness, number of active coils, and coil diameter. Because the basic spring rate characteristic is proportionally related to the thickness to the fourth power, a very small increase in thickness will result in a significant increase in spring rate.

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I also happen to have a left over custom made spring from my old BMW track day car and the comparison is quite amusing. The coil is miles thicker than either Porsche spring (and it's only a 450lb spring, which isn't that insane) and you can't bend it a mm by hand. I can squeeze the H&R spring and get quite a bit of deflection!
The H&R spring is a variable rate spring - initially it is relatively soft (thus you can deflect it by hand) but then progressively stiffens as deflection increases (note the progressively increasing diameter of the size of the coil and the decrease in coil spacing). H&R does this to create a shorter spring that provides a reasonably smooth ride over small bumps (initial compression) but is stiff enough that the spring provides good support and avoids bottoming out over large bumps (middle to full compression).

H&R sport springs are intended to replace the stock springs while lowering the ride height - they are not intended to increase spring rate significantly over stock (but this does happen to some extent just because the springs ultimately have to be stiffer to provide approximately the same overall spring rate in a shorter spring.)
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Old 07-13-2013, 09:49 AM   #10
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Johnny, honestly, there's zero chance that Eibach lowering springs are that stiff.
You're right. I was confusing those specs with my PSS9's. Maybe this will help.
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Old 07-13-2013, 10:08 AM   #11
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Thanks Johnny - not sure where you are getting your numbers for the PSS9s, but I doubt they are as stiff as 450/500.

Bit disappointed at the spring rates of the H&Rs, though I kind of knew just looking at them they were pretty soft...

I'll probably go with the H&R as I do want the extra drop. I have enough experience with springs to know that you need a surprisingly big change in rate to make a dramatically different feel in practice.

On my old E36 BMW I started with stock springs and dampers that were probably around 200lbs and went through several increments before I settled on 650/550 (though bear in mind this was with adjustable dampers that were also custom valved to cope with high spring rates). People get very excited about how slightly stiffer lower springs destroy ride and dynamics, but the reality is that going from, say 200lb to 250lb doesn't make much difference, truth be told.

I also learned that it's firm damping not firm springs that make things really uncomfortable.
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Old 07-13-2013, 10:13 AM   #12
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Originally Posted by pothole View Post
Thanks Johnny - not sure where you are getting your numbers for the PSS9s, but I doubt they are as stiff as 450/500.

Bit disappointed at the spring rates of the H&Rs, though I kind of knew just looking at them they were pretty soft...

I'll probably go with the H&R as I do want the extra drop. I have enough experience with springs to know that you need a surprisingly big change in rate to make a dramatically different feel in practice.

On my old E36 BMW I started with stock springs and dampers that were probably around 200lbs and went through several increments before I settled on 650/550 (though bear in mind this was with adjustable dampers that were also custom valved to cope with high spring rates). People get very excited about how slightly stiffer lower springs destroy ride and dynamics, but the reality is that going from, say 200lb to 250lb doesn't make much difference, truth be told.

I also learned that it's firm damping not firm springs that make things really uncomfortable.
Those spring rates are accurate. That's what 9ff decided on - based on my initial desire to track the vehicle. I'm definitely paying for on the street though. I pretty much have to run the PSS9's on full soft.
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Old 07-13-2013, 10:18 AM   #13
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Ah, I see - you mean those are custom spring rates? Fair enough.

I meant that I very much doubt the standard spring rates for PSS9 for 986 you buy off the shelf are that stiff. If they're custom, obviously I wouldn't argue!
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Old 07-13-2013, 10:25 AM   #14
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I believe PSS9 springs are around 280-300.
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Old 07-13-2013, 10:32 AM   #15
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Sounds about right!
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Old 07-13-2013, 11:47 AM   #16
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Ah, I see - you mean those are custom spring rates? Fair enough.

I meant that I very much doubt the standard spring rates for PSS9 for 986 you buy off the shelf are that stiff. If they're custom, obviously I wouldn't argue!
Yes they're custom. 9ff chose the spring rates based on the type of driving I was planning on doing. They're significantly stiffer than standard PSS9's. Most people that I know who have them, typically run theirs anywhere from 6 to 3 for street. I can't run mine any stiffer than 6 on the rear and 8 on the front unless I want my dental work to fall out.
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Old 07-13-2013, 02:59 PM   #17
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The coil spring rate is simply characterized by the thickness, number of active coils, and coil diameter. Because the basic spring rate characteristic is proportionally related to the thickness to the fourth power, a very small increase in thickness will result in a significant increase in spring rate.



.
Indeed .
I am yet to sit down and do the math , or write a spreadsheet

I have the porsche figures including row m030 , and all German manufacturers have to give it to get tuv approval to sell in Germany so have eibachs h&r and vogtland too .
Let me know if you can use the info ...

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