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Old 02-15-2010, 09:59 PM   #301
antonch
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Quote:
Originally Posted by Daishi00 View Post
No, seats are a part of the issue, but not it entirely
Seats are the issue. It has been stated by many, including Myles, before.
Shocks do not change resonant frequencies.
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Old 02-15-2010, 10:22 PM   #302
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Originally Posted by AndyRoo View Post
Good post Arnie, and I agree. But you didn't insult anyone in your post, maybe you forgot to throw a jab in or two?

Seriously, thanks for keeping it civil and productive. It gets out of control in here way too much.

- drew
No prob Andrew. No sense being obnoxious or absolutist. Its not very productive or helpful. Though certainly less fun! Besides, there's simply too many variables out there to say what's best for everyone. There are definitely lots of suspension philosophies out there and more than one way to skin a cat. Each with its pros and cons.

In general, I think we've got actually a few interesting technical ideas/mysteries being thrown around in this thread:

1. Why do some coilovers (expensive or cheap) have so little droop? Is it style? Is it meeting a price point? Is it copying "real" race cars?

Which leads us to:

2. What is zero/low droop and what performance advantages/disadvantages does it have? How does it work?

From some of the reading I've been doing its not just for Formula type cars, people are doing it with Mac strut with similar results.

Whether or not this type of suspension has its place on a street going car is obviously up to debate. Same with 10k springs on a street car on all season tires. Some things are just pure taste, some lack of insight. But like many say, its your car, you decide!
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Old 02-15-2010, 10:25 PM   #303
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Quote:
Originally Posted by Daishi00 View Post
No, seats are a part of the issue, but not it entirely
This.

You can, for instance, take an 04 STi, which has bobblehead, and replace all 4 struts with D-Specs while changing nothing else. Bobblehead is gone. Yes, I've personally done this.
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Old 02-15-2010, 10:31 PM   #304
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Originally Posted by antonch View Post
Seats are the issue. It has been stated by many, including Myles, before.
Shocks do not change resonant frequencies.
Shocks may not change the frequencies, but, obviously springs do. And its this critical pairing of the right spring with that damper that helps smooth things out. Sure, seats do contribute to the bounce effect that stock STi suspension have. But, one of the largest contributors to the bobble head (and believe me, we've been debating and experimenting with this issue since I joined this board in 2000, back when there was no RCE) is the spring rate paired with the STi damper. From the get go, we found that mating a stiffer spring to the STi damper netted a much smoother ride. For example, the V8 JDM STi pink springs gave a much smoother ride compared to the stock V7 or V8 springs. Even smoother than V8 RA springs (which were stiffer than standard V8 but softer than the pinks).

Just read Ty's response. He's correct too. I've also mated various incarnations of STi springs to adjustable dampers (AGX, Koni, DSpec) and they all ride much smoother than the standard STi spring/damper combo.

Last edited by Arnie; 02-15-2010 at 10:40 PM.
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Old 02-15-2010, 10:50 PM   #305
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Here is an example. Someone upgrades to a coilover, bobble-heat still remains. They change out the seat, and bobble-head is gone forever.
So what is the real cause and what is just a band-aid fix?

I've said it before and will say it again. Stock STI is overdamped, which mostly likely why firmer springs feel smoother. I remember I loaded my trunk with groceries from Costco once. I thought to myself, wow the ride feels much smoother maybe I should always leave my trunk loaded.
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Old 02-15-2010, 10:58 PM   #306
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Quote:
Originally Posted by antonch View Post
Here is an example. Someone upgrades to a coilover, bobble-heat still remains. They change out the seat, and bobble-head is gone forever.
So what is the real cause and what is just a band-aid fix?

I've said it before and will say it again. Stock STI is overdamped, which mostly likely why firmer springs feel smoother. I remember I loaded my trunk with groceries from Costco once. I thought to myself, wow the ride feels much smoother maybe I should always leave my trunk loaded.
It's both! both contribute to the situation. For example, I had installed various STi setups on an 02 WRX. Much better and stiffer seats than the 04+ STi seats. We had bobble head till we went to the pinks. I've also had examples of what you are describing. Major bobble head at low speed on coilovers, regardless of what we did with the damping. He swapped in a Recaro fixed bucket and the bobble went away for the most part. At least in from the driver's seat. It was still there from all the other seats. As opposed to the example of using pinks on the sti dampers. The bobble was reduced on the whole car, from all seats.

Here's a good article describing spring frequency and mentions exactly your situations of increasing weight in the car and how that tends to smooth things out.

http://autospeed.com/cms/title_Sprin...7/article.html
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Old 02-15-2010, 11:38 PM   #307
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Ok, I have a questiont that may be able to be answered while were on the subject. I have a car that must be able to be driven on the street somewhat reliably and comfortably. I have been looking into Feal Suspension's sti strut revalve service, and I want to revalve for 400f/r. With stock sti struts revalved, using tender springs on a 8 inch main spring will I have sufficient droop?
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Old 02-15-2010, 11:46 PM   #308
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Droop is set by the strut in that case. So long as you maintain the full stroke of the OEM damper during the revalve, and I can't think why that wouldn't be true, you'll be ok.
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Old 02-16-2010, 01:27 AM   #309
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WTF is bobblehead?
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Old 02-16-2010, 04:57 AM   #310
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Originally Posted by JDwhiteWRX View Post
WTF is bobblehead?
The first 23 seconds make it clear:


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Old 02-16-2010, 07:45 AM   #311
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Quote:
Originally Posted by Arnie View Post
It's both! both contribute to the situation. For example, I had installed various STi setups on an 02 WRX. Much better and stiffer seats than the 04+ STi seats. We had bobble head till we went to the pinks. I've also had examples of what you are describing. Major bobble head at low speed on coilovers, regardless of what we did with the damping. He swapped in a Recaro fixed bucket and the bobble went away for the most part. At least in from the driver's seat. It was still there from all the other seats. As opposed to the example of using pinks on the sti dampers. The bobble was reduced on the whole car, from all seats.

Here's a good article describing spring frequency and mentions exactly your situations of increasing weight in the car and how that tends to smooth things out.

http://autospeed.com/cms/title_Sprin...7/article.html
Bingo!

We have experimented with a friend of mines car as well with this (04 STi). I even had the problem on my WRX originally when I had STi takeoffs installed (the seats in the 05 suck as much as the STi's). T2's made the problem go away for me, my friends car is running JDM Pinks and it's decreased substantially, although not gone. He's got a set of Recaro's in the basement that will fix that last bit that he has.
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Old 02-16-2010, 11:01 AM   #312
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Quote:
Originally Posted by Dubstar112 View Post
Ok, I have a questiont that may be able to be answered while were on the subject. I have a car that must be able to be driven on the street somewhat reliably and comfortably. I have been looking into Feal Suspension's sti strut revalve service, and I want to revalve for 400f/r. With stock sti struts revalved, using tender springs on a 8 inch main spring will I have sufficient droop?
don't forget his strut insert project is only for WRX takeoff struts. NOT for STi struts. He has yet to develop those.
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Old 02-16-2010, 11:12 AM   #313
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Originally Posted by Arnie View Post
don't forget his strut insert project is only for WRX takeoff struts. NOT for STi struts. He has yet to develop those.
I think that's why he said revalve service. They can do that to STi struts.
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Old 02-16-2010, 11:17 AM   #314
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Originally Posted by aaronmsadler View Post
I think that's why he said revalve service. They can do that to STi struts.
duh!!!! brainfart! sorry, carry on. Its not like I'm subscribed and participating on that thread or anything. Too early for me still.
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Old 02-16-2010, 11:19 AM   #315
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Now that options like that are available, I have no idea why anyone would get cheapo coilovers.
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Old 02-16-2010, 11:27 AM   #316
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True! Unfortunately there aren't a lot of 04 STi struts laying around (for us non 05+ STi folk) and not as many JDM parts importers anymore. I miss JDM PARTS TX. They always had great deals and selection on JDM suspension parts.
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Old 02-16-2010, 12:31 PM   #317
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Don't forget that your tires can also be a factor to the bobblehead. For example on my wagon, if I use Toyo T1R or Bridgestone Blizzak (which are both too soft for my rates), I get bobblehead, switch over to the Toyo R1R and it's gone.
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Old 02-16-2010, 01:27 PM   #318
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Don't forget that your tires can also be a factor to the bobblehead. For example on my wagon, if I use Toyo T1R or Bridgestone Blizzak (which are both too soft for my rates), I get bobblehead, switch over to the Toyo R1R and it's gone.
Different sidewall stiffness or even tire pressure can greatly affect the overall ride frequency. When the ride frequency matches that of a person on the seat, the result is resonance or bobblehead.
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Old 02-16-2010, 03:09 PM   #319
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Another "zero droop" thread. This time on Hybrid Z. You'll have to register or wait 60 secs to agree to their terms and view the threads. Definitely more interesting reading:

http://forums.hybridz.org/showthread.php?t=128079


Here's a quote from Tube80z

Quote:
Keep in mind I'm not an expert, I play in parking lots with traffic cones, and occasionally run up mountain roads but here's what I know about reduced droop.

If we have a car with 500 pound springs, 500 pounds of corner load, and a motion ration of one, what happens when you set the car on the ground? I think the spring compresses one inch. What happens if I lift the car anything over an inch? I think the spring becomes unseated and there's no load on the tire (I'm not counting the unsprung weight in this case).

So in the case of reducing droop to less than an inch I'm keeping a set amount of load on the tire. This is very similar to how the stock suspension works by having a soft rate and a spring the is longer than the available space and it's pre-loaded. I'm just using a lot less space.

So here's what I think happens. Droop limiting either via pre-loading the spring on the strut, or using a mechanical stop allows the car to accept lateral loading and roll a specific amount before the inside spring tops out. At that point there is a certain amount of vertical load still left on the inside tire. For any further load transfer (and the necessary increase in lateral loading) the actual roll center moves to the center of the inside tire contact patch. For any further roll (from increased lateral loading) the car now pivots about that point, and lowers itself. That lowering in turn decreases the jacking effect. Roll stiffness from the springs and bars is not changed at all, so the net effect is a decrease in roll stiffness (or at a minimum, no further increase)

When I started running stiffer springs (400 to 500 pound range) it was obvious when jacking the car up the springs would unseat with very little droop. I noted the fender gap when this happened. I then looked at pictures I've taken of the car under high lateral loads and saw that sometimes the gap appeared to be bigger than just having the spring unseated. I remembered back to playing with formula cars running droop limiters and figured why not try this on a tin top. My original idea was that it didn't do any good to allow the suspension to droop anymore than the spring becoming unseated, which was a little over an inch (lets say 30 mm).

Running the car this way it worked better. I didn't see tires come of the ground and more importantly the rear tire temp were more even. Previously they looked to have too much camber. So then I played with this some more. I tried reducing droop at both ends to see what happened, then one or the other. I found a way to make a killer drift car (not what I wanted) and a way to get quicker turn-in and less roll, which was what I was after.

Pictures of the car after it was droop limited have a lower roll angle. I think this is attributed to the car no longer being able to jack the inside up off the spring seat because it now has to overcome a specific load. It's sorta like running a larger swaybar and the car works better. Theory tells you that's wrong but sometimes it works anyway. In this case I think the tires are held flatter to the road.

Cary
If I actually tracked my car still I would rebuild my Group 4's using the longer droop limiters just to see what all this stuff is about! Who knows, maybe I'll give it a try after I've done a few Nürburgring sessions to compare and contrast.

Last edited by Arnie; 02-16-2010 at 03:16 PM.
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Old 02-16-2010, 03:24 PM   #320
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Good thing I have an account over there... they've been discussing lifting a front inside wheel for a long time too.

Some of the guys on that forum do amazing work and really take lots of time to check things out and experiement. I guess it's easier when the car is usually not a DD.
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Old 02-16-2010, 03:47 PM   #321
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Well, since that platform has been tracking since the late 60's.... I'd hope they'd have a wealth of knowledge on setting it up for track.

but yeah, i think its "easier" to concentrate on setup if its "just for track".
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Old 02-16-2010, 10:39 PM   #322
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1. Why do some coilovers (expensive or cheap) have so little droop? Is it style? Is it meeting a price point? Is it copying "real" race cars?
I would say with the types of coilovers in question, all of their design attributes come from trying to find the fastest least expensive way to crank them out and make them modular, or have many interchangeable parts between models to create a part that will yield them the best profit margin per set. I think achieving the best performance gains per vehicle is usually an afterthought, if it's ever really a thought at all.

Quote:
Originally Posted by Arnie View Post
Which leads us to:

2. What is zero/low droop and what performance advantages/disadvantages does it have? How does it work?
As far as with "real race cars" (which is hard to classify here, as everyone has very varying opinions on whats is considered "real") often tend to focus on a very small window of suspension travel. Usually due to extremely high spring rates, unconventional suspension design and heavy emphasis on grip via aero, rather then tying to find it mechanically. I know this is usually the case when examining their amount of bump travel goes. And I suspect it's a similar train of thought when considering droop. Their willing to sacrifice droop for responsiveness, as they believe the car design won't permit many situations where large amounts of droop is necessary.

I think this pertains more to cars that we're designed and will live exclusively on race tracks, and the entire car "in the whole" is designed similarly. As far as our cars are concerned, I think preserving as much travel as possible in both directions will be beneficial for just about all the things we will plan on doing with them.

-Anthony

Last edited by Vaughn Performance; 02-16-2010 at 10:44 PM.
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Old 02-17-2010, 07:22 AM   #323
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F1 has so little suspension travel simply because if they change height even a few mm it could totally ruin the aero which is how those cars stay fast. They're trying to get back to mechanical grip, but it really hasn't happened yet.
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Old 02-17-2010, 12:13 PM   #324
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^ how do you explain the droop in the more mechanical vs aero grip series like the gt2 class of the alms?



I think i'm sort of confused by the points that are being thrown out here. there seems to be some that think that a street travel setup is best for all things? and some that think a race travel is good for all things?
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Old 02-17-2010, 12:30 PM   #325
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And I guess that is the debate here for the folks!

I personally don't prescribe to only one or the other. I say, use the right tool for the job. But I'm currently on the trail for more information on the mysteries of zero droop.

Anthony/Vaughn makes some valid suggestions as to why the cheapies most likely choose the low droop route to emulate. But I also think its simply to copy the more expensive Japanese low droop setups (TEIN, Cusco, JIC) who probably copy the low droop setups of cars like your porsche pictured above. Because its "RACE INSPIRED". How much they actually understand the performance ramifications of such a setup is also up to debate!
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