Advice on spring rates. M030 setup.
09-16-2004, 11:45 AM
#31
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Flash - well spotted about my mistake with the diameters!... oops 
So plugging the new correct numbers in we get:
smallest mean diameter = 2.25 inches + 9.0mm = 2.60 in
largest mean diameter = 106 mm + 9.0mm = 4.53 in
K = (11.25 x 10^6) x (0.35^4)
------------------------------------
8 x 4 x [ (( 2.60 + 4.53) / 2)^3 ]
K = 168820.3
--------------
32 x (3.57^3)
K = 168820.3
------------
1456
K = 116 lb/in
mmm ....
You're right about the Paragon data I'm pretty sure. I think 0.65 is much nearer the figure than 0.56. My measuring, as you know, gave 0.7 and yours too was not close to 0.56 so look like a typo!...
Good idea about the load in the boot (trunk)! :-) mmmm could always get a couple of people to sit in it I guess.....
I also wish someone would just tell us! getting fed up of all these calculations!..
Matt.
p.s this site http://dspace.dial.pipex.com/prod/di...suspension.htm
is the one where it says the helpers are 120# (and also says about 70# effective rate at the wheel - maybe this is the 70 figure you have heard - the effective rate at the wheel??)
So plugging the new correct numbers in we get:
smallest mean diameter = 2.25 inches + 9.0mm = 2.60 in
largest mean diameter = 106 mm + 9.0mm = 4.53 in
K = (11.25 x 10^6) x (0.35^4)
------------------------------------
8 x 4 x [ (( 2.60 + 4.53) / 2)^3 ]
K = 168820.3
--------------
32 x (3.57^3)
K = 168820.3
------------
1456
K = 116 lb/in
mmm ....
You're right about the Paragon data I'm pretty sure. I think 0.65 is much nearer the figure than 0.56. My measuring, as you know, gave 0.7 and yours too was not close to 0.56 so look like a typo!...
Good idea about the load in the boot (trunk)! :-) mmmm could always get a couple of people to sit in it I guess.....
I also wish someone would just tell us! getting fed up of all these calculations!..
Matt.
p.s this site http://dspace.dial.pipex.com/prod/di...suspension.htm
is the one where it says the helpers are 120# (and also says about 70# effective rate at the wheel - maybe this is the 70 figure you have heard - the effective rate at the wheel??)
09-16-2004, 12:47 PM
#32
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lol - yup - i know i'm dizzy from the math - and this is the second go-round for me - you should have seen me when i had the engineer from eibach on the phone doing the geometry of the suspension and trying to figure this out
by the way, i had forgotten all about that site - up a little higher in the page there is a (wait for it wait for it) effective conversion rate of .65!!! - looks like i was right about the juxtoposition - ok then - cool - now we have solved that one - 120# spring which makes 70# at the wheel - stock coil effective rate is .65 and not .56 - whew!!! that also verifies my readings on my new suspension layout
now i can get back to my intake calculations - oh happy day
by the way, i had forgotten all about that site - up a little higher in the page there is a (wait for it wait for it) effective conversion rate of .65!!! - looks like i was right about the juxtoposition - ok then - cool - now we have solved that one - 120# spring which makes 70# at the wheel - stock coil effective rate is .65 and not .56 - whew!!! that also verifies my readings on my new suspension layout
now i can get back to my intake calculations - oh happy day
11-26-2004, 06:48 PM
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Just got alerted to this thread. I'll be back with some answers soon, I hope. The number has been questioned before and survived, but this may change. I assure it is not simply a misprint. The .56 number was not reversed in translation. Whether the number is good or not remains to be seen. I know the last time we brought this up with Koni they were leaning more toward 44% for the coils!
FYI, in the future if there is something you folks see that is messed up or even questionable on any of our sites, please do drop me a line. I'd love to weed out the bad info as quickly as possible. I'm available at skip@paragon-products.com or even dumbasstechwriterinloungepants@paragon-products.com
Will get back to this issue soon.
FYI, in the future if there is something you folks see that is messed up or even questionable on any of our sites, please do drop me a line. I'd love to weed out the bad info as quickly as possible. I'm available at skip@paragon-products.com or even dumbasstechwriterinloungepants@paragon-products.com
Will get back to this issue soon.
11-26-2004, 09:31 PM
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Originally Posted by flash968
dug up my notes and it looks like it's closer to .75 effective ratio not .56 - measurements of rested and compressed heights bear this out too - my 10" 250# springs compress 3.75" with an estimated rear load of approx 1400lbs, and stock being around 1600# - that would make a wheel rate of 188# - my butt-o-meter thinks it might be stiffer than that, which would mean i have less weight on the rear wheels than i think (very possible - haven't weighed corners since new suspension setup and car diet, and i am now at dead level ride height which may be transferring weight to the front a bit) - it definitely does not dip like stock when you bounce the rear end - very resistant to that - also does not compress under load like stock - both of these tend to make me think it's a bit higher wheel rate than 188, like closer to a little over 200
does that help or confuse things more? - i know my head is now spinning
does that help or confuse things more? - i know my head is now spinning
0.75^2=0.56
Tomas
11-26-2004, 10:43 PM
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WTF? M030 tow package??
So, the 968 was really Porsche's first stab at the SUV market.
Damian's right. Is there no end to the amount of horse bleep spread by so-called experts?
BTW, those helper springs go a long way towards eliminating the car's characteristic understeering.
Richard
So, the 968 was really Porsche's first stab at the SUV market.
Damian's right. Is there no end to the amount of horse bleep spread by so-called experts?
BTW, those helper springs go a long way towards eliminating the car's characteristic understeering.
Richard
11-27-2004, 11:48 AM
#38
Rich, the supposed guru at Hershey was the guy who spoke about the helper springs being part of a towing package. Utter nonsense, obviously (only mo30 cars towed??), he was wrong about plenty of other stuff as well during the talk.
11-27-2004, 12:03 PM
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tomas - no, according to the math the engineer at eibach did with me from physical measurements of the suspension geometry, the weissach site, the porsche numbers that karl from racer's edge dug up, and physical compression measurements with a number of different springs, all of which concurred, the final number to use in the formula is .65 for stock configuartion - it looks like the digits just got juxtoposed on the paragon site, and then plugged into a spreadsheet - the .75 is for my new geometry
skip - thanks for jumping in - i hope that gets sorted out soon - i had a series of conversations with jason and chuck, but to no avail - it has caused a number of questions to be asked that could easily be resolved by posting the source of the math - it would be very helpful if you could dig up your source - we all just want to get the cars working properly
skip - thanks for jumping in - i hope that gets sorted out soon - i had a series of conversations with jason and chuck, but to no avail - it has caused a number of questions to be asked that could easily be resolved by posting the source of the math - it would be very helpful if you could dig up your source - we all just want to get the cars working properly
