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      01-07-2009, 05:26 PM   #67
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Lowering will create more camber which normally takes away some understeer
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      01-14-2009, 06:10 PM   #68
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Quote:
Originally Posted by lucid View Post
Rldzhao, what one really needs to know is the effective spring stiffness vs. displacement. As I've said earlier, if you plot the force vs displacement curve for the H&R springs+stock bumpstops, you'll see that you will run into the really steep part of the curve sooner (the bumpstop curve will probably look like two straight lines with distinct slopes; the slope of the second line at larger displacement will be significantly higher than the slope of the line at smaller displacement). I appreciate you documenting H&R's answer, but I still think messing with the force vs. displacement curve in a significant way, especially during the initial displacement interval, without retuning the dampers is not sound. Nothing in their answer suggests they are doing the right thing here.

The other thing is that the H&R guy is making claims about how the Dinan bumpstops behave. Has he actually seen/tested one of them? How does he know how they behave exactly? I sure don't know, and would like to find out, but I suspect that he doesn't know either.
Lucid,

Do you feel that Dinan accounted for this force vs. displacement curve or do you think they have also messed with the curve in a significant way and thus are an issue as well without retuning? Really would love to hear your thoughts. Thanks!!

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      01-14-2009, 10:32 PM   #69
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Quote:
Originally Posted by e46e92love View Post
Lucid,

Do you feel that Dinan accounted for this force vs. displacement curve or do you think they have also messed with the curve in a significant way and thus are an issue as well without retuning? Really would love to hear your thoughts. Thanks!!

Cheers,
e46e92
If you read through all the posts, Dinan says that they've considered the system comprehensively. They made both the guide support and bumpstop shorter to allow for more travel before contacting the bump stop.

So, it seems that the Dinan setup would have closer behavier compared to stock, but we cannot know for sure w/o testing.
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      01-14-2009, 10:37 PM   #70
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Quote:
Originally Posted by aajami View Post
Another bump for any updates
Sorry... didn't really go through with it. I recently moved and put the stock springs back on due to the high driveways near where I live. Also it seems that many people have installed H&R and there hasn't been too many complaints, if at all.
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      01-15-2009, 06:34 AM   #71
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Quote:
Originally Posted by rldzhao View Post
If you read through all the posts, Dinan says that they've considered the system comprehensively. They made both the guide support and bumpstop shorter to allow for more travel before contacting the bump stop.

So, it seems that the Dinan setup would have closer behavier compared to stock, but we cannot know for sure w/o testing.
I understand what the thread said, but I want to hear Lucid's opinion on whether after reading all of the Dinan articles and their statements whether he feels they have. To be honest, I don't think any manufacturer was in the room with the //M suspension guys, so none of them really know why the frequencies of the springs were set at what they were set at. For example, assuming the frequencies Orb posted are correct, they seem much lower than what many would suggest for a "sports car". Now I understand our cars are not "sports cars" as a ferrari or Z06 but they perform well on the ring and are not just some sporty coupe; they were more purpose built than that. Which means the spring rates were set at that frequency because of something they did with the shocks and struts and the geometry of the suspension. All of those things are thrown out the window if Dinan, or any other manufacturer for that matter, sets the spring rates of their springs so that they deviate from stock; adding custom bump stops might address suspension travel but new springs affect so much more than just suspension travel.

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e46e92
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      01-16-2009, 11:37 AM   #72
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Quote:
Originally Posted by e46e92love View Post
Lucid,

Do you feel that Dinan accounted for this force vs. displacement curve or do you think they have also messed with the curve in a significant way and thus are an issue as well without retuning? Really would love to hear your thoughts. Thanks!!

Cheers,
e46e92
I have no way of knowing what Dinan might or might not have considered, but one must assume they have covered the basics and more. Dinan often receives recognition for doing thorough engineering analyses and testing for their suspension upgrades, but again, I am not in a position to judge as I have no detailed knowledge of their engineering design processes.

The kind of testing I proposed, obtaining force vs. displacement graphs will not necessarily prove that one set of springs is better designed than another as one must evaluate the suspension system as a whole. Any such data would satisfy our curiosities about one of the variables involved. This kind of got kicked off after a discussion on if the aftermarket springs are significantly stiffer than stock springs. The data would answer that question. If stiffness is changed significantly, one can argue that the dampers would need to be modified as well for optimal performance, but then optimal performance in what context, etc.
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      01-16-2009, 11:41 AM   #73
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Quote:
Originally Posted by rldzhao View Post
Sorry... didn't really go through with it. I recently moved and put the stock springs back on due to the high driveways near where I live. Also it seems that many people have installed H&R and there hasn't been too many complaints, if at all.
Sorry I dropped the ball on this. I got really busy. So, it sounds like your H&R springs are out? Maybe we can test those? I'll share the pics you posted with my friend to make sure we can constrain them during a compression test, and if you are still interested, we can collect some data.
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      01-17-2009, 01:06 AM   #74
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Quote:
Originally Posted by lucid View Post
Sorry I dropped the ball on this. I got really busy. So, it sounds like your H&R springs are out? Maybe we can test those? I'll share the pics you posted with my friend to make sure we can constrain them during a compression test, and if you are still interested, we can collect some data.
Sorry... already sold them.
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