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Discussion Starter #1
My chassis will be pretty stiff with the addition of F/R strut bar, TRD underbody brace, and L-tuned sways.

Will soon be adding Eibach springs. But given the stiffness of the chassis, the suspension will be doing a lot more work absorbing the impacts because the chassis will not flex as much due to the reinforcements.

My thinking is that a more aggressive shock will be required to damp out:

1. A stiffened(underbody Brace, strut bar, sways, Eibach springs) chassis COMPARED to:

2. A stock chassis with only Eibach springs.

Does this theory make sense? I was thinking the Tokico blues may be ok for just lowering springs, but considering the extra bracing, I may need to go more aggressive with the shocks. Any thoughts?

I'm leaning away from Bilstein because they were not designed for lowered suspensions. Are the illumina in the hard setting that different from Blues? Or should I go with Koni. I heard that quite a few Tokico owners changed their shocks for Konis. Is it worth the price difference for a heavily braced or stiffenend chassis? Thanks guys!
 

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I had bilstein shocks on my car without any bracing, and I found the ride to be very harsh and bumpy. After I put the bracing on (plp f/r strut bars, trd f/r braces) the car felt perfect. Solid as a rock. The bilsteins felt much better with the beefed up chassis.

So by reverse logic, your theory makes a lot of sense ;)
 

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Well if you consider the chassis as a suspension component and all loads encountered on a roadway are absorbed by the suspension then yes your theory is completely sound. Look at it this way, when your car hits a bump the first force that acts upon it is the wheel and tire. If the bump is small enough for the sidewall to absorb then the suspension does nothing, if its too large then the spring and damper act upon it, and if the bump is too large still then the chassis acts upon it (by flexing to accomodate the disturbance). That is how the suspension is engineered. If you change one component, like the spring/strut combo and make the force required to set them into motion the same as or higher then the force required to affect the chassis then the result is precisely what Joe described.

Sorry for the long winded response, but i figured some would benifit from a full explanation.
 

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your theory does not make sense. a tighter chassis does not require more shock damping. a tighter chassis only buys you better turn in reponse during hard cornering and overall feel. you do realize that when you car is flexing during cornering it is acting as an undamped spring. over considerable cornering loads will the chassis start to stretch over time. other than bracing, there is nothing else that tune out the flex. the harsher feel one gets when increasing bracing will cause your suspension to work better and more efficiently. with teh chassis flex variable out of the picture, the car will experience "realtime" loading, hence better road feel. i don't know if you meant to say that.

a more aggressively valved shock (as compared to OEM) is needed primarily when you start increasing spring rates and/or when you need better valving to compensate for varying terrain/track, and overall handling balance.

with that, i would lean towards the tokico illumina's (both rebound and compression adjustable) and koni yellow (rebound damping adjustable). both are adjustable. the koni's unlike the illumina's can be revalved to your specs and converted to double adjustable (separate rebound and compression damping).
 

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Discussion Starter #5
Thanks for your contribution everyone. My thought was that since the stiffened chassis will play a less active role acting as a undamped spring, the suspension spring will absorb a greater load now since the cornering forces will still be present and need to be absorbed somewhere.

Therefore, the spring will compress more and will require more aggressive damping. Many cars with increase rigidity gets higher spring and shock valving rates compared to their less rigid counterparts. (NSX vs NSX-Targa; Boxster versus Cayman)
 

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web1028x said:
a tighter chassis does not require more shock damping.
This is true, but let me add a twist. A stiffer chassis does not require more dampening, but rather, it allows you to get away with higher dampening rates.

The higher your spring rates and the stiffer your shocks, the for force is transferred to your chassis. With a beefed up chassis, it will be able to take the higher forces transferred without flexing and throwing your suspension geometry off.

So it doesn't require stiffer shocks, but it allows you to take advantage of stiffer shocks. And on the other hand, you could say, that stiffer shocks can require a stiffer chassis.
 
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