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Old 02-27-2007, 10:16 PM   #1
cmiovino
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Default Strut bar myth?

So yea, everyone bashes strut bars and the "fact" that they apparently do nothing. Well, import177 found this at http://www.tanabe-usa.com/strutbars/default.asp as we were discussing some issues with them.

"A very common error when installing tower bars, It is always recommended to raise the vehicle when installing so that the load of the shock uppermounts on the shock towers is relieved and balanced out. When raised, and the tower bar is placed onto the vehicle, the preload can be adjusted and set. After it is bolted on and the car is lowered, each shock tower will have equal load and will prevent independent movements of each shock. This will provide an extremely noticeable difference after installing. If a tower bar is installed on a car that is not raised, great benefits will be missed."

Could it be that everyone installs them wrong?

I really wouldn't think I'd matter THAT much, but it seems like it makes sense.

I dunno, disucuss!
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Old 02-27-2007, 10:21 PM   #2
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They apparently help some types of car and not others.

CL Developments did testing on a chassis rig and found them to do nothing on the WRX's.

You can be quite sure they will do nothing to help handling,...however,...they do help reduce NVH.

I installed a set of Creative Concepts fender braces and the cowl-creak and front end noise when going over bumps was noticably reduced. I then did a strut tower bar and it was reduced further. I'd say the strut tower bar was 1/2 as effective as the upgraded fender braces.

None of this stuff is big,...but I like a tight and quiet car,...and the combination of the two got me closer to that.
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Old 02-27-2007, 10:41 PM   #3
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In the install directions I received with my Whiteline strut bars, they stressed to make sure there is NO preload on the bar during installation (ie, car on level ground).

Quote:
Originally Posted by DuckStu View Post
CL Developments did testing on a chassis rig and found them to do nothing on the WRX's.
Very interesting... would you happen to have a link for this test, or is it just one you've heard of?
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Old 02-27-2007, 10:45 PM   #4
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It is common practice to tighten/torque any suspension component when it is under vehicle load.

The only reasoning I could see behind their theory is when a vehicle is suffering from extremely offset cross-weighting under its own load, and even that still wouldn't make much sense.

Adjustable strut bars, in my opinion, should always be installed under vehicle load and
adjusted in tension( )---><---( ), NEVER expansion( )<------>( ).

Last edited by Evil STI; 02-27-2007 at 10:51 PM.
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Old 02-27-2007, 10:50 PM   #5
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HELLO!!!! NASIOC! (first post...EVER!)

I made myself a rear strut bar last weekend. The bar acts like a turnbuckle allowing me to maintain tension. Whiteline has something like this. I installed it with the rear end raised and tightened it a significant amount, then dropped it and finished doing the deed. I did some pre and post runs and noticed a significant change in handling. My girlfriend also noticed the difference.

I am starting to learn about suspension and chassis engineering. I cant say I can completly back it up with science. However, from experience i can say it tightened up my cars handling.

I installed a cheapo ebay front strut bar after my rear one and did not notice a change.

Maybe CL Developments hasn't noticed a difference because they haven't used one of mine. HEHE

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Old 02-27-2007, 11:18 PM   #6
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Just to be nit picky. Common wisdom is not that strut bars do nothing for a New Age Impreza, it's just that the chassis is already pretty stiff, so strut bars are not a great bang-for-your-buck mod for the novice modder.

AFTER one has done some significant suspension upgrades and springs/struts/swaybars have been stiffened properly, THEN strut tower bars are a good follow up.

AND, a rear strut bar is always a good idea to stiffen up the hatch area of a wagon.
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Old 02-27-2007, 11:30 PM   #7
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Quote:
Originally Posted by DuckStu View Post
I installed a set of Creative Concepts fender braces and the cowl-creak and front end noise when going over bumps was noticably reduced. I then did a strut tower bar and it was reduced further. I'd say the strut tower bar was 1/2 as effective as the upgraded fender braces.

None of this stuff is big,...but I like a tight and quiet car,...and the combination of the two got me closer to that.
+1 for the front strut bar then... this in itself is motivation for me to do it to my daily driver.
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Old 02-27-2007, 11:38 PM   #8
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Welcome to the club, Max! Whiteline does have a mechanism similar to that to adjust for manufacturing tolerances (and probably so they can use the same center piece for multiple applications).

Oh, and fill out your user profile so we know what car you have, etc.
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Old 02-27-2007, 11:41 PM   #9
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Quote:
Originally Posted by cmiovino View Post
"A very common error when installing tower bars, It is always recommended to raise the vehicle when installing so that the load of the shock uppermounts on the shock towers is relieved and balanced out. When raised, and the tower bar is placed onto the vehicle, the preload can be adjusted and set. After it is bolted on and the car is lowered, each shock tower will have equal load and will prevent independent movements of each shock. This will provide an extremely noticeable difference after installing. If a tower bar is installed on a car that is not raised, great benefits will be missed."
so would a non adjustable type, like a Cusco Ti be useless then ? seems like thats the implication
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Old 02-28-2007, 12:11 AM   #10
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i have only personal experience,and no scientific data to back it up, but i personally think there is some benefit. my evidence? shortly after i bought my car, it's super-expensive heated windshield cracked. funny story, it happened while i was driving (slowly) over a speedbump on the top level of a parking garage. huh, that's weird! after replacing it, it cracked again a few weeks later, in the same place, following the same pattern. replaced and cracked again, in the same place. none of these occurred from damage due to rocks, etc. or maybe only one; i can't remember now, but anyway i found a greddy strut tower brace real cheap, threw it on, and 3 years later i have not had another mysterious cracked windshield. i think the car was just flexing in certain areas enough to torque the glass. the strut brace seems to have added just enough rigidity to help the problem. i wouldn't spend a bundle on one, though.
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Old 02-28-2007, 12:40 AM   #11
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I think STB's are great. I have a GC tho so it's pretty much required. I noticed a difference going from a crappy 2.5RS steel STB to an STI carbon fiber STB. Still need to install the Ai cowl stays. If you can hear it creak I assume that can't be good.

cheers

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Old 02-28-2007, 12:52 AM   #12
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Quote:
Originally Posted by Mark Avery View Post
Just to be nit picky. Common wisdom is not that strut bars do nothing for a New Age Impreza, it's just that the chassis is already pretty stiff, so strut bars are not a great bang-for-your-buck mod for the novice modder.

AFTER one has done some significant suspension upgrades and springs/struts/swaybars have been stiffened properly, THEN strut tower bars are a good follow up.

AND, a rear strut bar is always a good idea to stiffen up the hatch area of a wagon.

THIS is the MYTH....the GD chassis is not as stiff as everyone wishes so badly to believe it is.

Stiffer than the GC, YES.......but what's good about being al dente as opposed to over cooked
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Old 02-28-2007, 02:44 AM   #13
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Yeah I agree with US, can't imagine it's THAT much better than the GC chassis. They are, after all, very similar in design. If you're running stiffer suspension the effects will be more noticeable but it's never a bad idea IMO. Pretty cheap mod anyway. 150 for a front STB 150 for rear STB. Peanuts.

cheers

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Old 02-28-2007, 03:01 AM   #14
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I believe the S203, S204 etc have strut bars from the factory. Element Tuning's time attack car has a FSTB.. thats good enough reason for me. =) The rear STB made a difference on my FXT.
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Old 02-28-2007, 03:09 AM   #15
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Quote:
Originally Posted by Uncle Scotty View Post

THIS is the MYTH....the GD chassis is not as stiff as everyone wishes so badly to believe it is.

Stiffer than the GC, YES.......but what's good about being al dente as opposed to over cooked
Whereas you make this claim to appear edgy and unique, I have actually looked into it and found some data.

CL Development's test data for torsional stiffness:

Note, the lowest value recorded on this plot is 13,500 lb*ft/degree and the highest is around 23,500.

Now here are some quotes from various websites discussing the torsional stiffness of their vehicle chassis:
That last quote is from a Winston Cup Car designed to handle extreme G loading in high speed banked superspeedway turns.

So tell me again how the GD Impreza isn't a stiff chassis? Nonetheless, there is clearly improvement to be had from chassis bolt-ons like triangulating strutbars (such as the X-Brace), and other products such as lower arm bars and fender cowl braces.

Regarding simple strut tower braces, cornering loads tend to pull the strut towers apart whereas vertical impacts push them together. Putting the strut bar biased in tension or compression will result in one of these being improved and the other being worsened. This is why you should install it statically and torque everything tightly to spec to get the best overall improvement.

Last edited by nhluhr; 02-28-2007 at 03:14 AM.
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Old 02-28-2007, 05:00 AM   #16
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Nice data.
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Old 02-28-2007, 05:25 AM   #17
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If i had a GC i would defeintly work to stiffer cowl braces and front a rear brace. If i had a sedan i probably wouln'dt worry with a rear strut brace. (i mod conservatively, budget minded)

But i have a wagon and i hear creaks and such and the plates over my rear struts rattle at times, so i know there is flex, i feel the flex over the lentgh of car when i shake the wheel side to side that i don't notice at all or as much in a sedan.

Read this guys its pretty nifty, http://en.wikipedia.org/wiki/Subaru_Impreza_WRX

theres a part about GC vs GD


One thing for wagons to think about : the EVO wagon IX has a very well engineered strut brace in the rear, not a bolt on and off but actually welded in most likely to take into account that space. (also interesting that they don't have the torque split thing eitehr on it,,,, some thought cost, some thought better weight ratio= not necessary
brings up another question : how much bar = how much stiffness in strut bar type, the sti wagon strut bar looks beefier than the whiteline one even though its more $ and no release, would there be a benifit? (anyone have measurements of one or the other to compare)



BTW scotty i felt my strut tops cause i was curious, and it did give a little bit easier than i thought when i'd push it with my finger.

Last edited by uathatis; 02-28-2007 at 05:42 AM.
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Old 02-28-2007, 06:39 AM   #18
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Quote:
Originally Posted by uathatis View Post
Read this guys its pretty nifty, http://en.wikipedia.org/wiki/Subaru_Impreza_WRX

theres a part about GC vs GD
great article and worth quoting in this thread:
==================================

GC chassis comparison to the GD chassis
Pros

Subaru claims that the GD chassis is 148 percent and 82 percent stiffer in torsional and beam rigidity, respectively, than the GC chassis. This stiffness is primarily due to the addition of a steel "ring" which encircles the cabin at the B-pillar. Due to the increase in stiffness, the car has much better stability in corners and is easier to control at the limit. The GC chassis is so weak compared to today's cars that engineers called the body a "Watermelon frame", referring to how a watermelon shatters on impact.

In terms of safety, the GD chassis scored much higher than the GC chassis and earned a "Good" rating (highest mark) from the IIHS's offset crash test. 4 stars front driver, 5 star front passenger and 4 star side safety ratings from the NHTSA. In a magazine article from the Dec. 2005 Firehouse magazine (a periodical written and made for firefighters), Ron Moore writes how it is well-known that the Impreza chassis has great protection in its B-pillars. This side structure has 8 layers of high-strength, high-tension steel including a round steel bar running through the middle. The author notes how drivers simply walk away from horrific side-impact accidents.

Cons

The GD chassis gains nearly 200 kg in weight over the GC chassis. Most of this weight comes in the form of chassis stiffening as the car was made to meet every country's crash standards. The weight also hampers the cars maneuverability, transistions and turn-in capabilities. [citation needed] The GC Imprezas were notable for being very lightweight despite having AWD. The WRX Type R STI Version VI using the GC chassis, at 1260 kg, was lighter than the competiting Mazda RX-7 type RZ (1270 kg) and Honda NSX type S Zero (1270 kg). In this fashion, the GC chassis has a better advantage.

The author of the forementioned article also notes that the Jaws of Life need to cut the Subaru's B-pillars at certain points in order to cut through the car frame[4]. This information was not widespread before, so there have been many incidences where firefighters could not cut the B-pillars due to their structural integrity. This may become a concern if the driver or passengers need to be cut out of the vehicle quickly.
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Old 02-28-2007, 08:12 AM   #19
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Good information in this thread.

I do have a question regarding the fender braces vs the strut bar... these both work to limit the motion of the strut towers, correct? If the strut towers are believed to be pretty stiff to begin with, then why would a fender brace provide that much mroe benefit than a strut bar? My understanding is the fender braces attach the strut towers to the a-pillar, which means the strut must move a good amount relative to the a-pillar... or else people wouldn't find these so nifty. But isn't the argument against a strut bar that the struts are so close the firewall that it's not as effective?

Maybe I'm confusing the a-pillar with the firewall.

Also... good thread for reference, similar discussion:

http://forums.nasioc.com/forums/show...ighlight=strut
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Old 02-28-2007, 11:06 AM   #20
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Quote:
Originally Posted by nhluhr View Post
Regarding simple strut tower braces, cornering loads tend to pull the strut towers apart whereas vertical impacts push them together. Putting the strut bar biased in tension or compression will result in one of these being improved and the other being worsened. This is why you should install it statically and torque everything tightly to spec to get the best overall improvement.


You have a missprint or brainfart there nhluhr

Cornering loads try to move both strut tops in the same direction, not apart.

The struts are "hinged" if you will, on the lower control arm (acts like a fulcrum). Below that, at the tires' contact patch,...they are trying to move to the inside of a turn (tires pulling the car around the turn),...and as a result, on the top end of the strut,...they are trying to move to the outide of a turn. The strut that is on the outside wheel in a turn is trying do do so more forcefully than the inide strut as it's tire has more weight on it and therefore more traction,....maybe that's what you mean. Both going the same direction, but one doing so more than the other, so they will spread apart a bit if anything.

So to sum it up,........If you are in a hard left-hand turn,....the left strut top is trying to move to the right a bit, and the right strut top is trying to move right even more.

That's the main fault of most strut bars,....they don't triangulate to the firewall,..but instead, merely connect 2 things that are both wanting to go in the same direction (in a turn). Here is an APR one for the EVO,...it does triangulate to the firewall.
http://www.aprperformance.com/index....=119&Itemid=44


When going opver a bump,...there isn't much increase in side load to the strut top, just a spike in the upwards force and then a slight decrease. The strut towers will very flex slightly up and down,...but shouldn't do much side to side I wouldn't think.
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Old 02-28-2007, 11:38 AM   #21
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Quote:
Originally Posted by DuckStu View Post
You have a missprint or brainfart there nhluhr

Cornering loads try to move both strut tops in the same direction, not apart.

...So to sum it up,........If you are in a hard left-hand turn,....the left strut top is trying to move to the right a bit, and the right strut top is trying to move right even more.
I think you and nhluhr are saying the same thing... he didn't say they try to move in opposite directions... just that they move farther apart from one another. And therefore placing the strut bar under tension, vs compression when you hit a bump.
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Old 02-28-2007, 01:03 PM   #22
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...I think much of the 'stiffening' is due to having drive wheels at both ends and thus the resulting mass has to be controlled in a bit different manner than a NON-awd platform

After having installed many of these chassis stiffeners---on BOTH my WRX's and others cars, and seeing posts on cracked glass and chassis nioses(and having had the same issues)............it is my conclusion that the overall chassis stiffness is the myth and adding many of these chassis braces makes for a much more enjoyable enthusiast platform.

There is a HUGE ammount of mush in the factory bushings as well which contributes to the overal noodle feel of the car....and removing the mush of the bushings reveals the flex in the chassis....which must then be addressed.
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Old 02-28-2007, 01:12 PM   #23
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Quote:
Originally Posted by nhluhr View Post
great article and worth quoting in this thread:
==================================

GC chassis comparison to the GD chassis
Pros

The author of the forementioned article also notes that the Jaws of Life need to cut the Subaru's B-pillars at certain points in order to cut through the car frame[4]. This information was not widespread before, so there have been many incidences where firefighters could not cut the B-pillars due to their structural integrity. This may become a concern if the driver or passengers need to be cut out of the vehicle quickly.
I have run into this issue before being a firefighter myself. For reference, the B-post is 6 or 8 layer corrugated steel with a high tensile boron rod run throught the center and as of now ther are only 2 cutters that can cut through it.
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Old 02-28-2007, 01:44 PM   #24
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Quote:
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I think you and nhluhr are saying the same thing... he didn't say they try to move in opposite directions... just that they move farther apart from one another. And therefore placing the strut bar under tension, vs compression when you hit a bump.
Exactly. If somebody wants to call me on this, you better do your goddamn homework first. In a 1G corner, the load pushing the inside tower is almost 0 and the load pushing the outside tower is very large. This causes the towers to be pulled apart relative to each other.

Last edited by nhluhr; 02-28-2007 at 01:49 PM.
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Old 02-28-2007, 02:22 PM   #25
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Why aren't there more 3 point triangulation front strut bars for the GD (or the GC for that matter) on the market?
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