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Old 04-16-2006, 10:45 AM   #1
RaceComp Engineering
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Default SO the new 2007 STi Limited is coming,should'nt this car have a more compliant strut?

Ok, so SOA answered some of our wishes( thw wrong ones) and produced a "laid back" version STI. More "M3" like with black Brembo's, Leather, new Euro color, Euro style rear lip spoiler, front V-limited(wow actually), and new more subtle wheels from the Spec-C.

So the last time I drove a M3 I didnt get bounced around like I was a in a blender. I remember a very tight, yet compliant ride quality that was up there with 911's , and other high end sports cars.

So the question is.................should Fuji/SOA have installed a set of Bilstein fixed perch dampers on this car to MATCH the "theme" of the new model?
These are available in Japan now. I know because we are trying our arses off to get them here, but it is very, very difficult. Thats not the point. The point is , there are now 2 available dampers that could go on this car that would actually raise the bar per say and offer a true "Limited" type, M3 beater performance and ride quality to this Japanese super car.








Your thoughts people.

Myles
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Old 04-16-2006, 11:01 AM   #2
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Myles

That's the first thing I looked for when the specs were posted. Like you, I'm baffled that they "civilized" everything about the car EXCEPT the suspension.

_Jeff
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Old 04-16-2006, 11:43 AM   #3
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Quote:
Originally Posted by Portly
Myles

That's the first thing I looked for when the specs were posted. Like you, I'm baffled that they "civilized" everything about the car EXCEPT the suspension.

_Jeff
EXACTLY, so I am not alone in this ..............GOOD !!

Myles
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Old 04-16-2006, 11:51 AM   #4
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same thing is available in Japan for the Impreza now. This is for the Legacy that is due soon.



mw
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Old 04-16-2006, 11:49 AM   #5
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you certain the suspension did not change at all?

<----cant wait to run part numbers
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Old 04-16-2006, 11:59 AM   #6
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you certain the suspension did not change at all?

<----cant wait to run part numbers
I feel VERY sure that it didnt change to the Bilsteins.....

Had they changed to the Bilsteins they could have used that in the marketing, which isnt happening obviously. But if it did come with the Bilsteins, then thay would represent a CHANGE and UPGRADE for the rest of the 05-06 sTI owners.

Yes Jamie( good point) I do think the valving in the rear by default has changed due to the updated rear shock(issue). But its still going to have that overall same super reboundish feeling versus say how the Spec-B feels with good springs on it.

Myles
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Old 04-17-2006, 01:19 AM   #7
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Hello,

Myles, the real question is whether, if they didn't upgrade the struts, they will upgrade the struts when you bring your '07 STI into the dealership with the typical STI inverted strut knock.



I'm looking forward to swapping my '05 for the '07, but maybe this time, if the struts start knocking, I'll swap to KW instead of constantly fixing / replacing bad OE struts.

Joel
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Old 04-17-2006, 09:14 AM   #8
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Maybe they have changed the struts but didn't advertise it since that would essentially be saying "the standard STi struts ride like poo".
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Old 04-17-2006, 10:27 AM   #9
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Quote:
Originally Posted by jweiss
Maybe they have changed the struts but didn't advertise it since that would essentially be saying "the standard STi struts ride like poo".
One woud think that if they had a fix for the CLUNK, they would at least upgrade this new model with it. I have always felt the Japanese could valve a car without a ton of low speed rebound, I hope this car is better.

Myles
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Old 04-17-2006, 11:09 AM   #10
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Quote:
Originally Posted by Joel Gat, 1.8L
Hello,

Myles, the real question is whether, if they didn't upgrade the struts, they will upgrade the struts when you bring your '07 STI into the dealership with the typical STI inverted strut knock.



I'm looking forward to swapping my '05 for the '07, but maybe this time, if the struts start knocking, I'll swap to KW instead of constantly fixing / replacing bad OE struts.

Joel
Good call....as I think the 07 will have some small positive CHANGES that will be good the all of us eventually.

mw
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Old 04-17-2006, 12:50 PM   #11
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That car is fantabulous!! if it was civil as well, that would be the ULTIMATE!!! Come omn SOA!!!...Give us a bit mroe compliance!!
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Old 04-17-2006, 03:23 PM   #12
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What exactly is being referred to here by "a more compliant strut"?

More compliant valving? Or a different strut design that doesn't suffer from the problems the KYB/STi struts presently seem to be suffering (i.e. bouncy ride on smooth roads, clunking sounds, stiction)?

On the valving side, what could be improved? I would say that the multiphased valving presently employed in many of the KYB/STi inverted struts (i.e. Ver 5, Ver. 7) does a very good job of absorbing the rough stuff (when functioning correctly), while still providing a very sporting ride.

If it's a different design, that doesn't suffer the ills of the KYB/STi design, what evidence is there that Bilsteins would be the answer? What is it about there design that would offer better performance over the KYB/STi hardware? If I recall correctly, the word was that KYB licenses some of the technology used in the STi strut design from Bilstein. Also, didn't DMS blame some of the problems they had with their DMS Gold 40mm struts on bad guides they sourced from Bilstein? The guide for the strut cartridge in an inverted strut is very important and is a likely culprit in clunking and sticking STi struts. Lastly, didn't Prodrive WR (Bilstein sourced struts) suspension owners complain of a bouncy ride as well?

With regard to Ohlins fixed perch struts, they do have a significant design difference, an internal reservoir. There is a fixed plate, with valving, between the floating piston and strut piston which forms the "internal reservoir". The valving in that fixed plate performs a similar function as that of the valving on a remote reservoir or the foot valve of a twin tube strut. With the early reports being all positive on the Ohlins, I'd be curious as to what other design differences there are over the STi units? Better guide design? Beefier piston shaft?

If it is a new design that is being sought after, why does everyone seem so set on inverted struts? Has anyone ever done the math on the bending stiffness of the STi inverted strut cartridge vs the WRX's very beefy strut shaft? What what be the resultant camber change for a given lateral load due to the bending? Are we talking here, a .1, .2, .3 degree difference when pulling .80, .85, .90 Gs? Of course, this would be assuming the guide could keep the strut cartridge straight relative to the lower housing. Which by evidence of recent pictures, it can't. Correct me if I'm wrong, but don't many of those European cars use McPhereson strut set-ups up front with non-inverted struts? If that's the performance and ride quality being sought after, then why the insistance on inverted struts?
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Old 04-17-2006, 03:42 PM   #13
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Hello,

The problem with Japanese struts and shocks is, and has always been, in my opinion, a problem with excessive high speed damping. For the performance you get, you always have a harsher ride than necessary. A good example is to compare almost all of the Japanese aftermarket struts for our cars to the German struts. The KWs, for example, perform better than almost any of the Japanese struts and feel more comfortable! True, it's a combination of factors including the fact that lots of the Japanese coilovers include too-stiff springs, relative to the performance you get, but a big part of the difference in _feel_ is the high speed compression damping.

My 2005 STi has two problems. (1) the struts clunk. Bilstein has decades of experience building inverted struts and I've never heard of anyone complaining that they clunk. Many people over the decade or more that Subaru has used KYB inverted struts, have complained about the clunk. I don't know why my car clunks, but I do know that no fix implemented so far works to remove the clunk.

And (2), the STi's shocks are valved for too much high speed compression damping. Every bump in the road bounces me into the air. The spring rates are SOFT! 200 pound springs on a nearly 1:1 motion ratio strut system should feel soft and compliant. Certainly, when you feel an STi running 3-400 pound springs on good coilovers, you don't get bounced around nearly as much. Why? Because the high speed compression damping is less and the wheels are allowed to move up and down and follow the road and the springs can do their job properly.

What's the problem with "proper" high speed compression damping? It doesn't feel as ricey / "sporty" in the minds of consumers.

It would be AWESOME if Subaru would spec the same or slightly stiffer springs for the new STI and then properly match the struts to the springs, without going overboard on the high speed compression damping. Then the car would handle better and feel more "compliant" / comfortable.

Just in my opinion, of course.

Joel
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Old 04-17-2006, 03:54 PM   #14
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^^^ What he said. I'd like less bump damping. I don't care it it's inverted or not, as long as it is a design that works.
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Old 04-17-2006, 04:48 PM   #15
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Joel,

From what I've read in these forums over the years, is that in many members opinions the STi struts, particularly Ver 5 and Ver 7, are much more on the compiant side than your typical Japanese aftermarket products.

I believe most of the STi struts being grouped together here have multiphased damping. The force velocity curve starts off with a steep slope for good low speed damping (body control) and then tapers off to a gentler slope for more forgiving high speed damping. Struts with a digressive curve typically have less high speed damping than a strut with a linear curve providing similar body control (low speed damping).

On paper, the posted shock dyno curves for some of the STi units depict curves, that in theory, should provide decent ride quality. However, due to various flaws, design traits, and other factors not yet fully understood, the STI inverted monotube stuts end up providing a ride quality that does not match it's valving. Put that same relative valving, giving the same damping curve, and hence the same amount of high speed damping, in a non-inverted twin tube design and I think you'll end up with a much more comfortable ride over the long term.

If your struts are knocking/clunking, then they're not functioning properly. The noise most likely comes from the lower end of the strut cartridge making contact with the inside wall of the lower housing. When this happens you end up with metal rubbing on metal. The additional friction alters the damping and causes stiction.
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Old 04-17-2006, 10:50 PM   #16
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Quote:
Originally Posted by Joel Gat, 1.8L
Hello,

The problem with Japanese struts and shocks is, and has always been, in my opinion, a problem with excessive high speed damping. For the performance you get, you always have a harsher ride than necessary. A good example is to compare almost all of the Japanese aftermarket struts for our cars to the German struts. The KWs, for example, perform better than almost any of the Japanese struts and feel more comfortable! True, it's a combination of factors including the fact that lots of the Japanese coilovers include too-stiff springs, relative to the performance you get, but a big part of the difference in _feel_ is the high speed compression damping.

My 2005 STi has two problems. (1) the struts clunk. Bilstein has decades of experience building inverted struts and I've never heard of anyone complaining that they clunk. Many people over the decade or more that Subaru has used KYB inverted struts, have complained about the clunk. I don't know why my car clunks, but I do know that no fix implemented so far works to remove the clunk.

And (2), the STi's shocks are valved for too much high speed compression damping. Every bump in the road bounces me into the air. The spring rates are SOFT! 200 pound springs on a nearly 1:1 motion ratio strut system should feel soft and compliant. Certainly, when you feel an STi running 3-400 pound springs on good coilovers, you don't get bounced around nearly as much. Why? Because the high speed compression damping is less and the wheels are allowed to move up and down and follow the road and the springs can do their job properly.

What's the problem with "proper" high speed compression damping? It doesn't feel as ricey / "sporty" in the minds of consumers.

It would be AWESOME if Subaru would spec the same or slightly stiffer springs for the new STI and then properly match the struts to the springs, without going overboard on the high speed compression damping. Then the car would handle better and feel more "compliant" / comfortable.

Just in my opinion, of course.

Joel
You need a job? ..nice explanation. Could not have said it better. Due to some commitments, I couldnt have said it.., so I am glad you did. ITs the truth.

Myles
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Old 04-18-2006, 09:36 AM   #17
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All in all, I think I would have rather seen Subaru go more of a WRX TR or EVO RS approach, reducing the cost instead of raising it.

The suspension is the one thing I would most likely tinker with, so if they just threw on the WRX struts with valving to match the springs, that would be fine.

Think of it this way, if they put on Ohlins, then they would be "stock". There would still be those that would feel compelled to swap out "stock" for something "better". The market would become flooded with Ohlin take-offs, and down go RaceComp's sales.

For the cost premium of the leather covering over what is likely to be the same basic seat, I'd much rather see Cloth covered Recaro seats (like in the EVO) for my money. Also, I'm not sure who started it , but isn't there a long thread about the seats being the cause of the bouncies?

The sunroof I could go either way on. If something like this were to be my only car, then it would be a definite plus. However, since I'm fortunate to have an open air roadster, I'd rather not have to pay the cost.

The combo of WRX sized hood scoop, Euro rear deck spoiler, and new front end treatment are all pluses in my book.
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Old 04-17-2006, 05:48 PM   #18
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Hello,

Scottie, whatever the reasons may be, and it seems that Subaru has not figured them out in more than a decade because inverted strut STis have been clunking since the first appearance in Japan of an inverted strut STi, the fact remains that they clunk. You can take the strut apart and regrease it and it will clunk soon after. Grease seems to help about as long as spraying LPS lube at the seal and hoping some gets through the seal (which it does, which seems to indicate not the best seal in the world). That clunking, however, seems independent of the high speed compression damping issue.

I have not seen the damping curves, but I would imagine the shocks have some insane amount of ... energy of activation? Yeah, stiction, whatever you want to call it, because I can tell you if a penny is facing heads or tails, despite having only 200 lbs springs. Like I said before, meanwhile, with a car running on KWs, Ohlins, Penskes, DMS 50s, etc etc etc., the spring rate can be much higher and you don't get that problem. So strut valving curves or not, there's something wrong with the OE struts that manifests itself in a way that is remarkably similar to too much high speed compression damping.

If they fixed that on the new STI Limited, that alone might be worth the $5k I'll be upside-down on a swap (yeah yeah, that same $5k would get me a sweet coilover setup... I know, I'm involved in professional racing... but... the whole combination of factors - subtle looks, improvements since 2005, heated seats, etc., that make it worth the upgrade to me). Heck, this new car will probably replace my STi and OXT as the one Subaru in my stable... and I'll probably bump up to an X-terra for my off-roading duties (able to crawl better, front seats fold to provide more than 7 feet of sleeping length, etc).

Joel
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Old 04-17-2006, 10:46 PM   #19
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Joel its good to know someone there are other people out there who think this way. Well put. Amen.

Myles
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