Sway bars

[Joeyy]

I think sway bars will be a first good suspension mod for the wagon. Perrin looks good with the end links or not? Any thoughts?

[sperry]

Not to be rude, but unless you have a specific swaybar question along the lines of "I running a 22mm front, 24mm rear swaybar setup and I'm still seeing understeer on corner entry", chances are your questions about swaybars have already been answered in other threads. Try searching here, on NASIOC, and on I-club... you'll probably find thousands of threads, including the specific application of Perrin bars on wagons.

Now, to address your question, on an otherwise stock suspension, a stiffer rear bar will help to reduce understeer. Wagons already have a softer rear bar than sedans, so just picking up a sedan rear bar will help. I've probably got one just lying around my garage if you're interested... make me an offer.

However, an adjustable aftermarket bar would probably suit you better since you can soften it up in the winter when you want to avoid oversteer.

As far as end-links... links don't make a bar any stiffer, however, they reduce the lag time between the car's weight shifting and the swaybar taking effect. So links will make a rear bar seem more "crisp".

One final thing about going to a stiffer swaybar, you should also upgrade your mounts as well. Having a bar tear out a mount is no fun.

[doubleurx]

And the perrin rear bars come with new mounts included.

[Paul@dbtuned]

Your stock sway bars are designed to work with the stock suspension.
That doesn't mean that the stock bars are the optimal ones for you.

Remember, engineers aren't the only people that designed our cars. Lawyers, bean counters, etc have influenced the design as well. And usually for the worse, from a performance point of view.

Now here's my theory...although I'm sure someone came up with it before me:

You will notice a difference running different sized bars, as long as the rest of the suspension remains unchanged.

For example, if install a 20mm rear bar, but keep stock springs, you'll get X amount of oversteer.

Now, if you install a set of coilovers with higher rate springs, and keep the 20mm rear bar, you'll get X-y amount of oversteer.


This is due to the coilover spring rate > stock spring rate, and the spring rate of the sway bar is unchanged.

Sway Bar Calculation info. (http://www.unofficialbmw.com/e28/suspension/e28_pete_read_on_sway_bars.html)
Calculation for solid bars (http://www.kormanfastbmw.com/tantiswa.htm)

I contend that if you select a swaybar for otherwise stock suspension, you'll need a different/larger bar if you change the spring rate of the suspension springs.

[Joeyy]

Thank you for your response to my question. :)

[M3n2c3]

That's good info.

[ScottyS]

I need to find oversteer first before I start worrying about having too much...

[Joeyy]

Ok, going to go with the Perrin rear bar with three way adjustment. They are off for the holiday but I need to call them. I want to make sure I don't have to order something WAGON specific.

[cody]

There *shouldn't* be anything wagon specific. I have a sedan (20mm) on my wagon (like what Sperry offered you) along with solid endlinks. The endlinks seemed to make as much of a difference as teh bar did. As it is, my wagon is as tail happy as I want it...although generally it feels very well balanced still erroring slightly on the side of understeer...unless of course I lift in turn 1...

[Nick Koan]

Are the endlinks still plastic composite on the new WRX's?

Moving from composite to metal is probably why you feel such a difference cody. Whereas, the STi (and others) have metal endlinks and you really only need aftermarket ones when the car is lowered and a sway bar is added (or stock height and a very large RSB).

[cody]

I didn't know any Subarus came with metal endlinks.

[Nick Koan]

My Legacy definitely does(did). I think STi's from 05 onward also does (maybe the 04s also, I dunno).

[Joeyy]

I'm going to use the Perrin end links with the 22 mm bar and probably change the front swaybar also with end links. I have to rotate the tires next week and do a oil change. When I do the rotation, I'm going to drop the Light Stars on to see how they look and check for clearance with the Falkens (just to make sure, so I'm not suprized in spring)

[ScottyS]

Hmmm............hey Scott, you still have your stock 20mm rear bar? I'm running a 17mm right now....I'll send you an offer.

[NevadaSTi]

Sorry to hijack the thread. But which is better, Perrin or Whiteline swaybars?

[cody]

I've heard Whiteline bars will rust prematurely, but that could be dated input.

[doubleurx]

The perrin has less options with regards to sizes, but mine hasn't shown any signs of rusting like my old cusco one did. The rsb from perrin also comes with new heavy duty mounts.

[sperry]

I've heard Whiteline bars will rust prematurely, but that could be dated input.
My Whiteline bar did pretty good for about 3 years and change, but I recently sanded it and repainted it since it was starting to see some surface rust where the paint chipped off. Now that I don't drive it in the winter (or at all it seems :() I figure it'll be a lot longer before I need to paint it again.

IMO, Whiteline is the best bang for the buck, plus they've got awesome customer support: I got one of the old front swaybars before the redesign to work with the '02+ front subframe. Whiteline sent me a new bar straight from Australia for free when I mentioned it to the pres. of Whiteline on NASIOC. :D

[Joeyy]

My swaybars arrived today :D

[cody]

Nice. Watch out for that snap oversteer...

[doubleurx]

Oh snaps!

[Kevin M]

obligatory text

[M3n2c3]

My swaybars arrived today :D
Let me know what you think of them. I'll probably do mine in a few months.

[Joeyy]

Well, I basically took all night putting on the rear sway bar. I used the Perrin solid sway bar mounts. The right side mount gave me the biggest problem. You use the old bolts and the rear one was to short. The rear bolt also holds down an attachment to a plastic box with all kinds of connections running from it. Don't have any idea what the box does. Anyway, I had to pass the bolt through the boxes mounting point, then through the new sway bar mount. The bolt just would not take on the frame side. After much contemplation, I cut off the lock washer on the bolt so it would reach a little deeper and maybe I could catch a couple of threads. It worked and I continued on. I also use the Perrin end links. The hole set up looks much diffrent from the stock and I think I completed the task correctly. No funny noises yet but I was driving home with all by tools in the back of the wagon so I couldn't rearly tell what was what. I had planned on installing the front sway bar also but the rear took everything out of me. I used the most rear hole of the three provided on the rear sway bar. We'll see how the thing feels after I have more confidence that I put it on correctly. I hate second guessing myself.

[sperry]

Wow man, that sounds a lot more complicated than it should be. It's been a while since I've done a swaybar and mounts, but it really shouldn't be more than an hour or two. And IIRC the hardest part is dealing w/ the fuel filler pipe.

Oh, BTW: that box is probably the charcoal canister that scrubs the emmissions.

[tysonK]

Yeah I'm a pretty novice installer but even I hammered out mounts, and a sway bar in the rear of my car in little over an hour.

What was the deal with the bolt? Maybe something on a new wagon that makes it harder?

That sucks it gave you so much trouble. It should be worth it though.

[Dean]

Sorry it was such a pain, but glad you got it in. Probably need to pick up a longer bolt and a new lock washer just to be safe...

[cody]

Call Perrin (ask for Jeff :P ) and complain about the bolt thingy. If it's a fitment issue (wouldn't surprise me), they should know about it. If it's an installation error on your part, you probably want to know.

I got sent the wrong EGT sensor once and the connectors didn't fit right. I was about to cut the wires and use butt connectors but I emailed the vendor and they told me it was the wrong sending unit. Just a thought.

[doubleurx]

The right side is the hardest with that plastic box; but holy crap, I think mine took about an hour and a half. I don't remember re-using the stock bolts though. It sounds like that ate up most of your time.

[MikeK]

When I did my rear sway bar months ago I had the same problem with the one rear bolt being too short. I ended up putting the stock bar back on so that I could drive to home depot and buy a longer bolt.

I ended up emailing perrin about it, and Jeff himself replied that they would start including a longer bolt with the kit. Either they decided not to bother, they just added the longer bolt for the STi kit, or you got a sway bar kit that has been sitting around at a shop somewhere for months.

[doubleurx]

I'm pretty sure mine had the longer bolt, because I don't even remember it being an issue with the only problem being access on the right side.

[AtomicLabMonkey]

When I did my rear sway bar months ago I had the same problem with the one rear bolt being too short. I ended up putting the stock bar back on so that I could drive to home depot and buy a longer bolt.

You didn't need to put the stock one back on just to drive down to the hardware store, just an FYI...

[MikeK]

I know, I decided that I didn't want any grief from my insurance company if I had an accident and they realised it was missing. Although if I have an accident now and they realise I have a stiffer rear swaybar I guess that would be worse :)

[cody]

I know, I decided that I didn't want any grief from my insurance company if I had an accident and they realised it was missing. Although if I have an accident now and they realise I have a stiffer rear swaybar I guess that would be worse :)
Insurance companie's don't generally deny claims because of mods, as long as you haven't removed safety equipment. horse's mouth (http://www.seccs.org/forums/showpost.php?p=49374&postcount=20)

[sperry]

Insurance companie's don't generally deny claims because of mods, as long as you haven't removed safety equipment. horse's mouth (http://www.seccs.org/forums/showpost.php?p=49374&postcount=20)
I wonder if I can argue that a FMIC adds as much crash protection as the bumper beam that it replaced. :?:

[cody]

I'm gonna go with...probably not.

[sperry]

I'm gonna go with...probably not.
Which is why I really need a truck and a trailer, so I can just register the WRX for off-road use only.

[cody]

What a tangled web you weave.

[Joeyy]

The right side nut at the control arm has loosened twice. Guess it's time for some loctite. For now, I'm driving around with a 14 mm socket in the car. It sucks climbing under a wet/snowy under carraige.

[Dean]

The right side nut at the control arm has loosened twice. Guess it's time for some loctite. For now, I'm driving around with a 14 mm socket in the car. It sucks climbing under a wet/snowy under carraige.Isn't that a nylock nut, or have a lock washer? If it isn't, I'd swap it for one instead of locktite.

[Joeyy]

I've used nylock bolts in the service but did not know about nylock nuts. Any idea were I could pick up nylock nuts, I'm totally sick of waiting for the next clunking noise. Thx-

[Dean]

Lowes, Home Depot

[doubleurx]

I wonder if I can argue that a FMIC adds as much crash protection as the bumper beam that it replaced. :?:


Me too. The Perrin Bumper Beam was so much beefier than the stock one.

[AtomicLabMonkey]

Once you get some proper nuts also make sure you torque the bolt to factory spec, instead of just "gettin it tight" with the socket.

[doubleurx]

Once you get some proper nuts also make sure you torque the bolt to factory spec, instead of just "gettin it tight" with the socket.


Proper nuts?, Isn't that a little personal.

[AtomicLabMonkey]

I was refraining from going there...

[Joeyy]

Blue lock tight has done the trick for one day so far so good.

[Joeyy]

Let me know what you think of them. I'll probably do mine in a few months.
It's finally dry enofe to have a little fun. I'm still running the stock tires, but the understeer is GONE. I have not yet changed out the front bar and I don't know how much that will change stuff. I'm running the rear bar on the middle setting. What class do you think you'll be running in in April?

[tysonK]

What class do you think you'll be running in in April?

Is that a trick question?

Whatever class you want, as long as the rules are followed.

[Joeyy]

Not a trick question. I was responding to M3n2c3's question. Also, I believe he has many more modes planned and I did not know what class he was going to end up in. So I asked...

[bruspeed]

So, all this talk about sways, I just bumped mine up to the last setting on my perrin, obviously snap oversteer is a huge deal now, I was curious though, Would adding a front sway kinda counter-act the tendency for the car to oversteer? I realize that it could very well increase oversteer, but the way the car is now, that would almost be welcome, seeing as how I can spin the car out at any moment. My train of thought here is that adding a front sway will help reduce the understeer of my full honk rsb, as well as adding some extra grip in the way of even less body roll. Correct me if I'm wrong.

[bruspeed]

So I did some searching and I think I'm gonna try adding a front sway bar to my setup. Worth a shot anyways.

[M3n2c3]

It's finally dry enofe to have a little fun. I'm still running the stock tires, but the understeer is GONE. I have not yet changed out the front bar and I don't know how much that will change stuff. I'm running the rear bar on the middle setting. What class do you think you'll be running in in April?
I'm gonna run STS. I've browsed through the allowable mods, and everything I had planned for the year would be ok. . . but I'm gonna have to cut back now that we have a young'n on the way. The best I can really hope to manage this year will be rims/tires before the season starts, a swaybar/links partway though the spring, and hopefully a lightweight pulley and intake/exhaust in the fall. My focus is on handling, though, so if I don't quite have the funds for intake/exhaust, I may settle for suspension bushings instead.

[bruspeed]

nevermind.

[Joeyy]

I'm adding the front swaybar soon. I just had to get the rear figured out first. Are you using the end hole or the one closest to the bar itself? I'm going to add STI pink springs before solo 2 season if they don't cost an arm and a leg.

[Kevin M]

You're on STi pink springs right Chris? I'd so go for it with the front sway. I always had a stock front bar on my RS, but I usually only ran the rear bar at full stiff for autocross, where the near-snap oversteer was welcome. If you can't find an adjustable, a 21 or 22mm fixed would still be good.

Joeyy, he's on the holes closest to the bar, farthest from the end.

[bruspeed]

You're on STi pink springs right Chris? I'd so go for it with the front sway. I always had a stock front bar on my RS, but I usually only ran the rear bar at full stiff for autocross, where the near-snap oversteer was welcome. If you can't find an adjustable, a 21 or 22mm fixed would still be good.

Joeyy, he's on the holes closest to the bar, farthest from the end.


No, Tanabe gf210's, but today I went and found a deserted lot and whipped the car around a bit and I'm very happy with it actually, I think I might try adding an adjustable bar like you said Kevin, but the car seemed surprisingly well balanced, with just a hint of oversteer, which like you said is kinda welcome in Autox.

[Kevin M]

It probably still won't like to throttle oversteer, especially with the open rear diff, but if you can get controllable snap oversteer (easy to cancel with a little counter steer) with quick lifts as you turn-in, you're pretty much set until you decide you need coilovers. I would only do chassis stiffening mods to the suspension after that.

[M3n2c3]

. . .you're pretty much set until you decide you need coilovers. I would only do chassis stiffening mods to the suspension after that.
Like strut tower bars? What are the pros and cons associated with those?

[Kevin M]

Pros: they're cool to list as a mod :p and they do stiffen up the chassis a bit, the rear more than the front. Every little bit helps.

Cons: Good ones, made of less flexible metal with proper design, cost more, usually $100-140 apiece. Also, the rear is a pain to install. Not worth doing unless you're swapping springs and/or struts at the same time.

[cody]

Pros: they're cool to list as a mod :p and they do stiffen up the chassis a bit, the rear more than the front. Every little bit helps.

Cons: Good ones, made of less flexible metal with proper design, cost more, usually $100-140 apiece. Also, the rear is a pain to install. Not worth doing unless you're swapping springs and/or struts at the same time.

I install and uninstall my Whiteline Strut bar all the time. :P

http://www.wrxfanatics.com/uploads/post-52-1128828319.jpg

[khail19]

Wagon owners have it easy. My rear strut brace takes a contortionist to get on and off.

[cody]

Wagons need one more than sedans so it's only fitting.

[bruspeed]

It probably still won't like to throttle oversteer, especially with the open rear diff, but if you can get controllable snap oversteer (easy to cancel with a little counter steer) with quick lifts as you turn-in, you're pretty much set until you decide you need coilovers. I would only do chassis stiffening mods to the suspension after that.


On-throttle oversteer is a LONG ways away. :lol: I think I will look into some strut bars and other stiffening things.

[sperry]

I install and uninstall my Whiteline Strut bar all the time. :P

http://www.wrxfanatics.com/uploads/post-52-1128828319.jpg
If you're not pre-tensioning that thing after taking it out and re-installing it, it's not really doing much to stiffen the rear.

[cody]

I've never heard that. Which way would you have me pre-tension it? Pushing outward or pulling inward?

[sperry]

I've never heard that. Which way would you have me pre-tension it? Pushing outward or pulling inward?
Unless you're able to get a ton of torque on that quick-release, the play in the bolt slot is probably more than the flex of the strut tops.

Pushing outward is how most do it, IIRC. But I don't have a quick release on mine, I just torqued mine down so it shouldn't move. If the threading on one of the ends of the bar is reverse, pre-loading is as simple as loosening the lock nuts and twisting the whole bar a few turns... but I don't remember if the Whiteline bar is threaded properly for that.

[cody]

According to this read (http://www.e30m3performance.com/myths/Strutbar_Theory/strut_bar_theory.htm), the bar is under tension (not compression) during cornering (which makes sense if you think about the force on the outside wheel during cornering). So, if anything, you'd want to pre-tension it, not pre-compress it...just to answer my own question.

2ndly, there is no discernable play in the quick-release bolts. They are very snug.

The Whiteline bar is not designed so you can simply spin the bar to lengthen and shorten it. You have to uninstall it on one side and spin the end piece that the Q-R bolt slides through to change its length. Perhaps I'll try to shorten it half a turn.

[sperry]

According to this read (http://www.e30m3performance.com/myths/Strutbar_Theory/strut_bar_theory.htm), the bar is under tension (not compression) during cornering (which makes sense if you think about the force on the outside wheel during cornering). So, if anything, you'd want to pre-tension it, not pre-compress it...just to answer my own question.

2ndly, there is no discernable play in the quick-release bolts. They are very snug.

The Whiteline bar is not designed so you can simply spin the bar to lengthen and shorten it. You have to uninstall it on one side and spin the end piece that the Q-R bolt slides through to change its length. Perhaps I'll try to shorten it half a turn.
Interesting read. It's a bit counterintuitive that the strut towers spread apart under smooth cornering force, but I can believe that.

If the bar doesn't spin for adjustment, there's really no way to put a decent pre-tension on it. If you've got to be able to slide the bolt through it while it's a its final length, you're screwed. I guess just making sure that quick-release is nice and tight is the best you can do.

[cody]

The bar really has no play in it at all. It's very well made from what I can tell. The threads are very fine so I'm going to see if I can at least squeeze another half turn to shorten the bar just a tad. Maybe with my big ass sitting in the rear, the extra weight will flex the towers inward enough to get a touch of pre-load.

[M3n2c3]

Hmm. I may have to add front and rear strut tower bars to my list for the year. Is that an appropriate progression from sway bars, or is there something else that I'd be better off upgrading?

[sperry]

Hmm. I may have to add front and rear strut tower bars to my list for the year. Is that an appropriate progression from sway bars, or is there something else that I'd be better off upgrading?
Front STB is more of an eye-candy part... they don't do much since the front strut tops are so close to the firewall.

[cody]

Hmm. I may have to add front and rear strut tower bars to my list for the year. Is that an appropriate progression from sway bars, or is there something else that I'd be better off upgrading?
I don't know if RS's are any less stiff than WRX's at the firewall and rear strut tower area, but most people concede that the benefits of a front STB are negligible and the rear is only slightly beneficial for a sedan.

Wagons are another story though since they don't get any structural integrity from the rear seat like sedans do.

[AtomicLabMonkey]

I wouldn't count on any brace that uses pivoting joints doing much of anything useful. If you want a stiffer chassis, use bolted or welded joints.

Oh, and this:

...but if you can get controllable snap oversteer (easy to cancel with a little counter steer) with quick lifts as you turn-in, you're pretty much set...

is an absolutely fabulous idea. :rolleyes:

[cody]

Monkey, the point of a RSB is to share the force flex between both strut towers. I fail to see how the pivoting joints take away from the usefulness of the bar. I wouldn't expect the bar to do anything other than keep the two strut towers at one constant distance from eachother (therby sharing the force exerted upon them). I think expecting a solid bar to keep the rear end "square" is asking too much of it.

[sperry]

Monkey, the point of a RSB is to share the force flex between both strut towers. I fail to see how the pivoting joints take away from the usefulness of the bar. I wouldn't expect the bar to do anything other than keep the two strut towers at one constant distance from eachother (therby sharing the force exerted upon them). I think expecting a solid bar to keep the rear end "square" is asking too much of it.
I've got this awesome rope pool cue I'll sell ya, it's highly transportable, all you have to do it wind it up and put it in your pocket!

...you can't have hinges in the bar if it's gonna work. That's why you need to torque down the mounts. And even then, it's not going to be a good as a welded in bar, but that's a little impractical.

[cody]

So you disagree that the main point of a strut bar is to keep the tops of the strut towers at a static distance from eachother then Sperry?

[Nick Koan]

I believe the strut tower brace is not only for lateral distance, but vertical distance (or lack thereof).

A STB with hinges will acomplish the first goal, but not the second.

[AtomicLabMonkey]

I think expecting a solid bar to keep the rear end "square" is asking too much of it.

No, it's not asking too much, because that's exactly what you want chassis bracing to do. When you drive a car on track most of its time in corners is spent with a combination of braking, acceleration & cornering loads acting on it. This twists the chassis torsionally. The biggest gains in suspsension sensitivity & handling improvement/better feel for the driver come when you improve that car's torsional rigidity. Braces with pivoting joints will do very little towards that end.

[sperry]

So you disagree that the main point of a strut bar is to keep the tops of the strut towers at a static distance from eachother then Sperry?
Sure, that's what it's for, but if the bar pivots at the mounting point, you might as well just use a come-along and winch the strut tops together w/ a strap since you're only restricting the distance in one direction.

[cody]

Sure, that's what it's for, but if the bar pivots at the mounting point, you might as well just use a come-along and winch the strut tops together w/ a strap since you're only restricting the distance in one direction.

The bar does restrict the towers from getting closer together and further apart...that's two directons.

[cody]

No, it's not asking too much, because that's exactly what you want chassis bracing to do. When you drive a car on track most of its time in corners is spent with a combination of braking, acceleration & cornering loads acting on it. This twists the chassis torsionally. The biggest gains in suspsension sensitivity & handling improvement/better feel for the driver come when you improve that car's torsional rigidity. Braces with pivoting joints will do very little towards that end.

Oh, because I assumed the biggest gains would be from maintaing suspension geometry. In this particular application, the bar inhibibits the wheels from losing negative camber due to latteral forces associated with cornering by sharing the forces between two strut tower instead of one.

[khail19]

I think a hinged strut bar provides some benefit as far as suspension geometry goes, but a solid bar also adds chassis stiffness as well.

[cody]

I believe the strut tower brace is not only for lateral distance, but vertical distance (or lack thereof).

A STB with hinges will acomplish the first goal, but not the second.

According to the link (http://www.e30m3performance.com/myths/Strutbar_Theory/strut_bar_theory.htm) I posted earlier:

Figure 1 shows the forces of interest in a strut bar analysis. For this calculation only horizontal forces need be considered. There are of course vertical forces, but since the sum of forces must independently equal zero in both the horizontal and vertical directions, we can concentrate on just the horizontal forces in this analysis.

http://www.e30m3performance.com/myths/Strutbar_Theory/stress_bar_theory.gif

and...

What a strut bar does is tie the two strut towers together so that they share the load applied at the outer tower. This gives you twice as much material to deal with the same cornering force and helps reduce fatigue stress in this area.

[cody]

I think a hinged strut bar provides some benefit as far as suspension geometry goes, but a solid bar also adds chassis stiffness as well.

I'm sure that's true to some extent. In fact, I should say the same thing about all everyone else's posts...except Sperry's. :P

[sybir]

Monkey, the point of a RSB is to share the force flex between both strut towers. I fail to see how the pivoting joints take away from the usefulness of the bar. I wouldn't expect the bar to do anything other than keep the two strut towers at one constant distance from eachother (therby sharing the force exerted upon them). I think expecting a solid bar to keep the rear end "square" is asking too much of it.

As much as this is fun to watch, it behooves me to point out that you're trying to argue suspension theory and chassis bracing with a guy who's day job is designing suspensions for race cars ;)

That said, a rear strut bar helped add a little torsional rigidity in the back of my wagon, as I can no longer hear the hatch twisting around during hard coornering like I could before....but that's a much bigger car with a much bigger hatch area than WRX wagon. I knew the QR's were a sacrifice, as you can't even tighten them effectively, let alone tension them with Whiteline's conventional threading.

And if you're saying the bar feels stiff, therefore it's helping, think about how stiff your suspension towers feel already......are you able to just swivel those around?

Strut bars are just a minor band-aid fix for larger dynamic issue that can only be effectively addressed with a welded-in, tensioned, triangulated brace.

[cody]

As much as this is fun to watch, it behooves me to point out that you're trying to argue suspension theory and chassis bracing with a guy who's day job is designing suspensions for race cars ;)

That said, a rear strut bar helped add a little torsional rigidity in the back of my wagon, as I can no longer hear the hatch twisting around during hard coornering like I could before....but that's a much bigger car with a much bigger hatch area than WRX wagon. I knew the QR's were a sacrifice, as you can't even tighten them effectively, let alone tension them with Whiteline's conventional threading.

And if you're saying the bar feels stiff, therefore it's helping, think about how stiff your suspension towers feel already......are you able to just swivel those around?

Strut bars are just a minor band-aid fix for larger dynamic issue that can only be effectively addressed with a welded-in, tensioned, triangulated brace.

I know he's a suspension engineer. I just think that saying a STB with a hinge is useless is exagerating. I'm not arguing as much as trying to bate him into educating me. :)

And no, I'm not saying that the fact that it's stiff is helping. I'm saying that the fact that it keeps the strut towers at a static distance means force is shared between two strut towers instead of one. :)

[khail19]

I think strut bars got popular because the aftermarket made them for cars that needed them first, maybe like old Civics and whatnot. Then everyone decided they wanted them for looks mostly, because most newer cars don't benefit much from them. Cars chassis stiffness has increased so much in the last decade that it's mostly a bling item now. Of course, the manufacturers will be happy to tell you other wise, but I couldn't really notice when I put mine on.

[AtomicLabMonkey]

Oh, because I assumed the biggest gains would be from maintaing suspension geometry. In this particular application, the bar inhibibits the wheels from losing negative camber due to latteral forces associated with cornering by sharing the forces between two strut tower instead of one.

Assumption... incorrect. The primary reason for stiffening a chassis is so the suspension springs, dampers & swaybars control a larger portion of the vehicle's kinetics - instead of the chassis acting as an additional spring. This leads to more predictable handling, and better, more noticeable response to suspension adjustments. Wheel alignment control is only a secondary benefit.

[Nick Koan]

According to the link (http://www.e30m3performance.com/myths/Strutbar_Theory/strut_bar_theory.htm) I posted earlier:



http://www.e30m3performance.com/myths/Strutbar_Theory/stress_bar_theory.gif

and...

True, but that whole article assumes that the strut towers are infinitely strong in the vertical direction. Which obviously is untrue. He is mostly correct, though, in saying that the horizontal forces are quite a bit larger, and there is also less strength bracing for horizontal forces. For the most part, having the bar in there with QR's is probably not totally worthless, but a solid bar would be better if you were trying to eek out every bit of performance.

[cody]

Assumption... incorrect. The primary reason for stiffening a chassis is so the suspension springs, dampers & swaybars control a larger portion of the vehicle's kinetics - instead of the chassis acting as an additional spring. This leads to more predictable handling, and better, more noticeable response to suspension adjustments. Wheel alignment control is only a secondary benefit.

I absolutely believe everything you wrote there, but you still haven't offered any evidence that a non-hinged STB does a better job at preventing the chassis from acting as a spring. I know it seems like it would to a certain extent, but any tiny amount of flex in the bar is going to negate the "stiffness" your depending on to hold the chassis "square". However latteral forces aren't really affected much at all by this flex.

[AtomicLabMonkey]

I absolutely believe everything you wrote there, but you still haven't offered any evidence that a non-hinged STB does a better job at preventing the chassis from acting as a spring. I know it seems like it would to a certain extent, but any tiny amount of flex in the bar is going to negate the "stiffness" your depending on to hold the chassis "square". However latteral forces aren't really affected much at all by this flex.

It's pretty simple; pinned joints can't resist moments (torques), but bolted/preloaded and welded joints can.

To keep with your square box analogy, if you have 4 pinned joints at each corner of the box, it will fall down if you push on the side of the box. If the 4 corners have rigid joints instead, it will stay standing if you push on the side of the box. I'll have to refer you to a statics textbook to get much more detailed than that.

[cody]

I'm just saying, it better be a VERY stiff joint to keep the box square. Thanks for humoring me.

[AtomicLabMonkey]

I'm just saying, it better be a VERY stiff joint to keep the box square. Thanks for humoring me.

No problem. Think of it this way - with rigid joints you at least have something resisting torque loading, vs. nothing with pinned joints.

Obviously it's not ideal; in an ideal situation you would only have pure tension/compression loadings in your structure. This is only possible when you start adding tubes which criss-cross the car, a.k.a. the roll cage.

[cody]

Right, everything about my car is a compromise starting with the fact that it's a "sport wagon". Every mod I have and will ever get shant take away from the versatility of the vehicle.

[MattR]

Good discussion boys..god damn....

So, wait until I tell you that I'm running no rear bar on the Sti. Double adjustable Coilovers and 8k springs FTW.

[sperry]

Good discussion boys..god damn....

So, wait until I tell you that I'm running no rear bar on the Sti. Double adjustable Coilovers and 8k springs FTW.
You took off your swaybar?

[khail19]

You took off your swaybar?

Aren't we talking about strut braces? It sounds like he took off his swaybar.

[cody]

You took off your swaybar?

Pretty sure he meant rear strut tower bar. The sedan doesn't really need one anyway.

[MattR]

Pretty sure he meant rear strut tower bar. The sedan doesn't really need one anyway.


Nope, I meant my swaybar. I am in new territory of suspension tuning...we shall see.

[Kevin M]

Oh, and this:

is an absolutely fabulous idea. :rolleyes:

In a mildly underpowered 3200 pound AWD car at a Solo 2... yes. On the street, not so much, hence the advice to get an adjustable sway bar and not run it stiff unless you want those handling characteristics. How much fun is driving a car that won't even mildly oversteer when you lift sharply after turn-in?
Also, by "snap overtseer" I mean, the rear tires break loose and yaw rate rapidly increases. Not necessarily going ass over teakettle into the nearest cones, weeds, or mountainside.

Background: Chris has been a passenger in my RS at Solo 2 and told me he liked how my car handled, and I've ridden with him in his caras well. He's probably better than me at not spinning his car when it oversteers, racing dirt tracks might have something to do with that. I know for a fact I'm not setting him up for failure by suggesting he add a stiff rear sway to his RS.

[Kevin M]

I think strut bars got popular because the aftermarket made them for cars that needed them first, maybe like old Civics and whatnot. Then everyone decided they wanted them for looks mostly, because most newer cars don't benefit much from them.

Yup. Think 240Z, Datsun 510, BMW 2002... all cars with long engine compartments and strut/shock towers smack in the middle.

[Kevin M]

Good discussion boys..god damn....

So, wait until I tell you that I'm running no rear bar on the Sti. Double adjustable Coilovers and 8k springs FTW.

Colin Chapman would be proud. :)

[AtomicLabMonkey]

In a mildly underpowered 3200 pound AWD car at a Solo 2... yes. On the street, not so much, hence the advice to get an adjustable sway bar and not run it stiff unless you want those handling characteristics. How much fun is driving a car that won't even mildly oversteer when you lift sharply after turn-in?
Also, by "snap overtseer" I mean, the rear tires break loose and yaw rate rapidly increases. Not necessarily going ass over teakettle into the nearest cones, weeds, or mountainside.

The fact that you're telling someone to compensate for factory designed understeer by inducing a poor handling quirk of that car with an even poorer driving technique is what prompted me to make that original comment.

[bruspeed]

Yup. Think 240Z, Datsun 510, BMW 2002... all cars with long engine compartments and strut/shock towers smack in the middle.


I was thinking about it, and while our cars may not suffer from the same extreme lack of rigidity you're examples displayed, we are not curing the problem simply by adding a STB. Think of it this way, Strut toweres are "flimsy" right? so what happens when you just add a bar across the tops of them? You get Two "flimsy" strut towers flexing together, whether it be front or rear, What I'm trying to get at is, unless they are triangulated, they aren't really doing much, and definently not there full potential. The front one needs to be tied to the firewall, the rear one can go to the floor for a third attaching place.

[MattR]

What I'm trying to get at is, unless they are triangulated, they aren't really doing much


Agreed. I think that simply linking them together is only adding little benifit. bracing it to something else makes sense.

[cody]

I was thinking about it, and while our cars may not suffer from the same extreme lack of rigidity you're examples displayed, we are not curing the problem simply by adding a STB. Think of it this way, Strut toweres are "flimsy" right? so what happens when you just add a bar across the tops of them? You get Two "flimsy" strut towers flexing together, whether it be front or rear, What I'm trying to get at is, unless they are triangulated, they aren't really doing much, and definently not there full potential. The front one needs to be tied to the firewall, the rear one can go to the floor for a third attaching place.
No doubt that would help...but then, of course, you're giving up even more trunk space, drilling holes in the car, and increasing cost. It may be worth it if your goal is to keep the chassis rigid, but the standard bars work well at preventing the wheels from losing negative camber from the towers flexing as you take a hard turn. This is because the outside wheel has as much as 100% of the latteral force in a corner (RE: lifting a wheel) the inside wheel's strut tower is experiencing little or no latteral force when the wheel is lifted, so you might as well use that structural integrity to supplement that of the "outside" strut tower.

[bruspeed]

Good discussion boys..god damn....

So, wait until I tell you that I'm running no rear bar on the Sti. Double adjustable Coilovers and 8k springs FTW.


So, I didn't really hear how you were gonna accomplish you're goal when everyone was chattin last night, You're gonna go 8k all the way around? will that create the same or similar handling characteristics as having the sway set to "full?" But still allow the suspension to really be independent?

[bruspeed]

No doubt that would help...but then, of course, you're giving up even more trunk space, drilling holes in the car, and increasing cost. It may be worth it if your goal is to keep the chassis rigid, but the standard bars work well at preventing the wheels from losing negative camber from the towers flexing as you take a hard turn. This is because the outside wheel has as much as 100% of the latteral force in a corner (RE: lifting a wheel) the inside wheel's strut tower is experiencing little or no latteral force when the wheel is lifted, so you might as well use that structural integrity to supplement that of the "outside" strut tower.


come on dude drill holes in you're car, tell them it was for "Love of the game"

[cody]

come on dude drill holes in you're car, tell them it was for "Love of the game"
:lol: Some of us are more "Extreme" than others.

*insert Mt. Dew here*

[khail19]

I've drilled (and Sawzalled and Dremeled) so many holes i my car I'm surprised it still holds together. Maybe it's lighter now. :lol:

[Kevin M]

Speed holes!

[M3n2c3]

All you need is an "H" gear and you'll be set. :lol:

[Joeyy]

Ok, back to sway bars. Now that my rear doesn't want to loosen up, I'm going to put the front in. Next is STI pink springs before April. Any idea on a good price and place to buy. I think I'll let a pro drop them in for me.

[bruspeed]

Ok, back to sway bars. Now that my rear doesn't want to loosen up, I'm going to put the front in. Next is STI pink springs before April. Any idea on a good price and place to buy. I think I'll let a pro drop them in for me.


Now, I may be wrong, but adding a front sway right off the bat will tighten the car up even more. And prevent it from rotating further.Try the springs first, I think that with a lowered car, and the sway bar set to full honk you'll notice things getting mighty hairy on long sweepers, and such especially when you let off the gas. I started with the sway, mounts and endlinks first (bought 'em used so I got a great deal) and at first, eh, it was a noticable improvement, then I added struts and springs and whoa was it ever noticable, that was on the middle setting, now that I have driven the car like that for the past year I finally went to the last setting on teh sway and it made a world of difference. I kinda have to be careful on on/off ramps as the car wants to get loose, but the car is noticabley more tossible. Just my $.02 :)

[dknv]

edit: I moved it to OT.