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.

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

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.

nevermind.

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.

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.

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.

Like strut tower bars? What are the pros and cons associated with those?

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/p...1128828319.jpg

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

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

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

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.

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.

According to this read, 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.

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.

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.

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.

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:

is an absolutely fabulous idea. :rolleyes:

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.

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?

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.

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.

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.

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.

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.

According to the link I posted earlier:

http://www.e30m3performance.com/myth...bar_theory.gif

and...

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

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. :)

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.

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.

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.

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.

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.

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.

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?

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

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.