The Topic Of The Third Spring


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#1 Cyril Ma

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Posted 28 February 2008 - 09:32 PM

I've gotten two questions by separate individuals with regards to the function of the 3rd spring, so I guess I'll post it here as well for the benefits of everyone who doesn't know its function.

The third spring first circulated among the CART circuit back in the early 90s.  I think it was the guys who worked for THE CAPTAIN who first toyed with the idea about a ride height control for the cars at high speed.  Downforce is a function of speed, and naturally the faster you go, the more DF you produce.

The more DF you produce therefore, the easier it is to compress the car into the ground, causing the car to bottom and if the bottoming happens on a high speed corner, then it really isn't a pleasant experience.  So to counter that, you have to run stiff corner springs  But the catch is, the stiffer springs you run (in real life), the faster your tires get destroyed and the level of mechanical grip is hindered severely, causing you to slide around in slow corners, leading to tires destruction.

So what the engineers did was to put a third damper between the two elements activated by something like a "T" mechanism in laymen's terms.  The T element allows the 3rd element to only be in play when BOTH dampers on that end are moving in the same direction (ie both in compression or both in rebound).  So now you can run a 3rd spring that's stiff to control the ride height during high speed straights to prevent from bottoming, and go back to running softer corner springs to gain back the mechanical grip that you would've otherwise lost.  The 3rd spring SHOULDN'T play a role in cornering because in a corner, the laden wheel is in compression while the unladen wheel is in rebound, thus the T mechanism of the 3rd spring isn't in play.

Hope that solves the confusion some people have with regards to the third spring :)

Edited by Cyril Ma, 28 February 2008 - 09:54 PM.


#2 Bruce Fisher

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Posted 28 February 2008 - 10:26 PM

Great description Cyril - thanks for sharing
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#3 Zorco Kirilian

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Posted 28 February 2008 - 11:12 PM

thank you  :thumbup:
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#4 GAb

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Posted 28 February 2008 - 11:37 PM

Agreed! Best read explination yet.

Does the mod represent the lack of its play in corners, and the true ability to help with bottoming out?
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#5 cbonsall

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Posted 29 February 2008 - 10:23 AM

thanks for the explanation, didnt know that fact. have any notes on packers? :D
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#6 Ian Grant

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Posted 29 February 2008 - 11:08 AM

Very well put Cyril, I've never actually been able to visualize the action of the thrid spring until now!

Charlie:  As far as I know, packers are along the lines of 'stops' to limit the travel of the suspension to prevent bottoming out under full compression.  Might not be a 100% accurate definition but I belive it is in the ball park, perhaps someone can expand on the subject.

#7 Mike Tyler

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Posted 29 February 2008 - 02:56 PM

Nice explanation Cyril. :thumbs: I should add that to the shock section of the setup guide because we forgot to cover the third shock elements.  

As far as the mod simulating the role of the third shock with bottoming out, it's somewhat limited though this is more about rFactor than the mod.  Part of what we ran into was that the effect of the increased down force at speed was being over compensated for and basically causing the cars bottom out beyond the point of their bump stops, which of course would be physically impossible in the real world.  So in order to get around this problem we had to make few "suspended reality" adjustments to the chassis settings.
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#8 Cyril Ma

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Posted 29 February 2008 - 03:18 PM

picture is worth a thousand words

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#9 Bruce Fisher

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Posted 29 February 2008 - 03:34 PM

gorgeous picture... but can you add some arrows pointing out key components?  I'm sure I'm not the only one that's not entirely clear what's what :)
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#10 GOGGLES PAESANO

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Posted 29 February 2008 - 03:43 PM

G1 Cyril!
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#11 cbonsall

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Posted 10 March 2008 - 05:45 PM

View PostIan Grant, on Feb 29 2008, 01:08 PM, said:

Very well put Cyril, I've never actually been able to visualize the action of the thrid spring until now!

Charlie:  As far as I know, packers are along the lines of 'stops' to limit the travel of the suspension to prevent bottoming out under full compression.  Might not be a 100% accurate definition but I belive it is in the ball park, perhaps someone can expand on the subject.

what i dont understand about the packers is the numbers and were they start from. say i have packers at .250 . now does that mean i`ve restricted travel by that number or is the the amount of total travel?
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#12 Greg Veres

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Posted 10 March 2008 - 10:13 PM

I'm with you charlie, a good packer description would be great to have.

I understand what they do and I think the answer to Charlie's question is that you are adding .25 inches of material to the damper so it has .25 inches less travel.

But my interested is more around what do they do for you and when would I use them vs. ride height adjustment. I understand that they limit the travel of the suspension by having the damper stop its travel on them. But what is the disadvantage of using them, how would I know I have to use more or less. That sort of thing.

Thanks
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#13 Cyril Ma

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Posted 11 March 2008 - 03:55 PM

You mainly use packers on cars w/o the 3rd spring, because the packers are just a form of ride height control that's way more primitive than the 3rd damper.  Do not confuse bump rubbers with packers.  One is compressible, the other is not.  

On cars where you can't run the third spring, you use this to keep the car from bottoming on the straights.  On a GT1 in Daytona for example, I'd probably run a bit of packers on the RHS of the car, just to keep the car from bottoming w/o having to sacrifice ride height.  You want the car to be loaded onto the packers BEFORE you get into the turn and have it stay there for the entire corner.  If it comes out and gets back on the packers, then it really is no different than having a car that's bottoming during those cornering speeds.   If you have motec, watch the suspension travel curve and the tire load curve.  Anytime you hit a HUGE spike in tire load mid corner suggests something that needs to be sorted out ASAP.

Denver is another place to put some packers on the car.  Usually at street tracks, you want to run the car softer than usual. (I'm biased in this regards as I like my car soft everywhere)

The soft setup would mean you have a greater range of motion on the higher speed stuff so you need the packers to be there to prevent the car from bottoming w/o sacrificing ride height.  Because a street track is usually bumpy and offer lower grip levels than permanent circuits, the soft springs and bars would let you have the mechanical grip you'd need to negotiate around the turns w/o excessive sliding, thus preserving your tires.

#14 Greg Veres

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Posted 11 March 2008 - 04:27 PM

Thanks, I need to hit the track to test some things out before I will claim I understand. :)

#15 cbonsall

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Posted 11 March 2008 - 07:38 PM

i dont run motec, never did figure out how to use it.  :angry:  :unsure:  does this mod throw sparks out  if the car scrapes the track? cause thats the only way i can tell . :blink:
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#16 GOGGLES PAESANO

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Posted 11 March 2008 - 09:00 PM

View PostCyril Ma, on Mar 11 2008, 04:55 PM, said:

You mainly use packers on cars w/o the 3rd spring, because the packers are just a form of ride height control that's way more primitive than the 3rd damper.  Do not confuse bump rubbers with packers.  One is compressible, the other is not.  

On cars where you can't run the third spring, you use this to keep the car from bottoming on the straights.  On a GT1 in Daytona for example, I'd probably run a bit of packers on the RHS of the car, just to keep the car from bottoming w/o having to sacrifice ride height.  You want the car to be loaded onto the packers BEFORE you get into the turn and have it stay there for the entire corner.  If it comes out and gets back on the packers, then it really is no different than having a car that's bottoming during those cornering speeds.   If you have motec, watch the suspension travel curve and the tire load curve.  Anytime you hit a HUGE spike in tire load mid corner suggests something that needs to be sorted out ASAP.

Denver is another place to put some packers on the car.  Usually at street tracks, you want to run the car softer than usual. (I'm biased in this regards as I like my car soft everywhere)

The soft setup would mean you have a greater range of motion on the higher speed stuff so you need the packers to be there to prevent the car from bottoming w/o sacrificing ride height.  Because a street track is usually bumpy and offer lower grip levels than permanent circuits, the soft springs and bars would let you have the mechanical grip you'd need to negotiate around the turns w/o excessive sliding, thus preserving your tires.

Cyril you're an effing Godsend, thx for sharing your knowledge with the rest of us (numbskulls, boneheads, dufii and the like).
Hubert Cheyroux

#17 cbonsall

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Posted 12 March 2008 - 03:33 AM

View PostGOGGLES PAESANO, on Mar 11 2008, 11:00 PM, said:

Cyril you're an effing Godsend, thx for sharing your knowledge with the rest of us (numbskulls, boneheads, dufii and the like).
who you callin names <_<  :moon:  :P
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#18 Congo_Toey

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Posted 17 May 2010 - 09:47 AM

Wow thanks Cyril Ma, what great help, I have been looking for exactly that information for weeks.  There was a reference to setup guide for shocks where can I find that?

#19 Mike Bennett

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Posted 20 May 2010 - 03:56 PM

View PostCongo_Toey, on 17 May 2010 - 09:47 AM, said:

Wow thanks Cyril Ma, what great help, I have been looking for exactly that information for weeks.  There was a reference to setup guide for shocks where can I find that?


You've dug up an old thread with this one mate.  This division has moved to a private server but these forums still exist.  Cyril himself hasn't been around since shortly after this thread was active.  Copy his post to a text file and save it somewhere safe :) It is a great reference for understanding the 3rd spring.  As for the shocks you talk about, I can't help you there, you could try to view all of CM's posts if you click on his profile and see if you find anything.  Anyway, here's some links I use.  Good luck!

http://www.wtrscca.o...ch.htm#tiretemp
http://www3.sympatic...e Brake Mapping




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