Springs, ARBs and load transfer...


Kozy

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Hi guys, thought I'd post up another one of the tools I've been working on, for checking how spring and arb changes affect steady state over/understeer balance and roll angles.

Black Art Racing - Load Transfer Calculator



It's defaulted to a DC2 because there is more information out there about them, but the standard setup is very similar to the EK9 so it should still be useful.

There's only two results at the moment, roll angle and front load transfer distribution, but a more advanced version will be available soon detailing load transfers, tyre loads, spring frequencies etc. I'd love some feedback on any aspects of it, the whole website is very much still a work in progress at the moment.

Issues I am aware of currently:
  • I know it might not render/work properly on older mobile devices. I am working on this.
  • Not compatible with Internet Explorer (but what is?). I do not intend to fix this, if you're still using it I would recommend getting a better browser! :p
  • Some anti-virus software apparently thinks the site is a source of spam. I assure you it is not but I will try and find out why this is happening.
Any questions, please ask! :nerv: :nice:
 

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Kozy

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No comments?

:alone:

Made some changes, updated the link.
 


SixEighteen

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Thanks for bumping. I'm messing around with it now, although I know it won't be exact for my EK9.

I had originally been planning to run 400lb/500lb (f/r) on my coilovers. But based off of this and the natural frequencies, it seems like I should be running 500/400.

What are your thoughts? 500/400 would put my frequencies around 1.78/2.31 which isn't too bad, being that 2-2.5 is the racing sweet spot, 1.5-2 is street/race sweet spot.

FYI - I'm subscribed to this. I wouldn't mind getting some really good technical discussion going about DC2/EK9 suspension setup in here.

Edit: running koni yellows, with rear helper springs and oem top mounts
 

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Kozy

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Cheers RVM!

I had originally been planning to run 400lb/500lb (f/r) on my coilovers. But based off of this and the natural frequencies, it seems like I should be running 500/400.

What are your thoughts? 500/400 would put my frequencies around 1.78/2.31 which isn't too bad, being that 2-2.5 is the racing sweet spot, 1.5-2 is street/race sweet spot.
Well 400/500 is a good autocross setup, but usually that means a bit too loose on the street. You'll probably notice also that if you double both springs, you actually get more understeer despite what you might think. Without changing the ARBs, adding proportionally more rear spring can help to keep the balance the same as stock, so you might not be too far off.

If you've got springs that can be swapped front and rear, you can always try both arrangements and see which you prefer! If you do that, let us know what you think of it!

ETA: Just had a look myself, and it seems that even 400/500 gives a bit more understeer than standard! Get a pair of each, try them each end! :nice:
 

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Sleeper Status

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Very nice.
Love seeing ppl getting technical :)

Would you happen to have the EK9 default values?
 

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Kozy

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Very nice.
Love seeing ppl getting technical :)

Would you happen to have the EK9 default values?
I don't have anything accurate enough to warrant using unfortunately.

I will enevtuallu be building up a database of cars though, across a range of marques, and all of this will require finding this data out. Just a matter of finding the people willing to contribute the information, there are people that measure this sort of stuff but they often tend to keep it to themselves as they see it as a competitive advantage.
 


Sleeper Status

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Know exactly what you mean.
I currently have a DC2 (USDM LS) but am definitely looking to a EJ9.
 


SixEighteen

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Cheers RVM!



Well 400/500 is a good autocross setup, but usually that means a bit too loose on the street. You'll probably notice also that if you double both springs, you actually get more understeer despite what you might think. Without changing the ARBs, adding proportionally more rear spring can help to keep the balance the same as stock, so you might not be too far off.

If you've got springs that can be swapped front and rear, you can always try both arrangements and see which you prefer! If you do that, let us know what you think of it!

ETA: Just had a look myself, and it seems that even 400/500 gives a bit more understeer than standard! Get a pair of each, try them each end! :nice:
I assembled the coils last night 500/400. But im thinking maybe i will swap them to 400/500 to try that first (since it was my original plan)

I will take note of how the car feels. Are there any measurements that youd like me to try and get when i do the install?
 


Kozy

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The motion ratios are really the most important detail, if you could get a measurement from the inner and out pivots of each LCA, and then a measurement from the inner pivot to the damper fork mounting point and inner pivot to the ARB mounting point, that would be a great start. I used to have these figures from my car but I've lost them! :nice:

The best way to do it is to have some way of measuring the displacement of the damper in relation to the wheel, I.e move the wheel up 1", measure the damper movement, repeat etc.

Bit of a drawn out job though so no worries if you canny be bothered!
 

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Kozy

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Updated the link in the OP. Page has been re-written with a faster interface, so it doesn't reload the page each time you make a change.
 



oifovo

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Awesome read Kozy!!!!
I spotted one little typo: " It terms of tyres, this manifests itself as the soft rubber deforming around asperities in the road surface" should read "In terms" I think!
I'm already looking forward to the next article!
 


Kozy

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I spotted one little typo: " It terms of tyres, this manifests itself as the soft rubber deforming around asperities in the road surface" should read "In terms" I think!
Cheers for spotting that! :nice:
 


Kozy

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Next installment online: "How to pick an initial spring rate setup for your car"

A look at the maths surrounding spring rates, wheel rates and ride frequencies, and how to use all this to pick a good base line spring configuration for your requirements, which we will later refine with by adding in anti-roll bars and checking the combined effects on load transfer distribution and roll angles. :nice:
 


Samuka88

1st EK9 registered in Portugal
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May 26, 2014
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Car(s)
JDM Honda Civic EK9 1999
View media item 8865View media item 8864View media item 8878I went sure in Japfest 2015 that my ek9 came lowered from Japan. Suspension is stiff and doesnt allow big load transfer. I feel every piece of road. I guess i have OEM dampers but not sure. Roll bars are OEM. This is 1999 ek9, produced in April 1999. Anyone can give an opinion about this?
 


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