Which of these two sway bars will best suit my needs?
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This is a discussion on Which of these two sway bars will best suit my needs? within the Suspension & Wheels forums, part of the Tech & Modifying & General Repairs category; Before I begin, let me say that yes I have searched the forums and done a lot of research on ...

  1. #1
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    Which of these two sway bars will best suit my needs?

    Before I begin, let me say that yes I have searched the forums and done a lot of research on this. I'm choosing between two sway bars, and would like to know which is the best route to take. A little about me and my car: It is 2012 WRX Sedan and a daily driver that will never see track use. All I am looking to do is eliminate some of the body roll and tighten things up a bit. I will be keeping my OEM front sway bar, and both the front and rear end links. This is both because I'm a college kid on a tight budget, and because for my needs I dont think I need any more than the rear sway bar. The first option I am looking into is the OEM STi rear sway. It is 19mm and would allow me to maintain a front sway bias. My concern is that it wont make a noticeable difference in daily driving. The second option I am looking at is the Epic Engineering 22mm rear sway bar. I am looking at this bar for a few reasons. First, it is one of the few aftermarket bars designed to be used with the OEM front sway bar, and safe for use with the stock endlinks. Secondly, it's fairly cheap. Finally, all the reviews I have found for it seem to be stellar. Having the 21mm stock bar in the front with the 22mm bar in the back should make my car fairly balanced, with just a very slight tendency towards oversteer. I think this is the set up I want to go with, but would like a few other opinions. Anyone care to chime in?

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    Master Baiter EJ257's Avatar
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    Front bar should be upgraded first


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    Registered User Impreza2.0's Avatar
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    For safety... front/both.

    Also when you shop for tires, not that there is a new need to do so, but when you do, ask what options exist for anything wider than you have now without sacrificing anything. Just see what your tire guys say.

    If they say keep it the way it is, follow their instructions. Otherwise, stiffer swaybars will wear your tires a little bit more than stock, since the tires absorb more roll. This increases wear at the edges of the tread.

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    I was under the impression that the OEM STi rear bar was safe to install on the WRXs. It is a mod many people have done. The Sti uses the same front bar size as the WRX from the factory, and they both use the same stock end links. Given that the Sti comes 21 front/ 19 rear from the factory, why would this be unsafe on the WRX?

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    Quote Originally Posted by EJ257 View Post
    Front bar should be upgraded first

    Honestly, I've read a TON of posts on this subject and I've never, ever, heard of this advice. 100% of the advice given on this forum so far has been to upgrade the REAR sway bar first. The OEM STi sway bar is 19mm compared to 16mm for the stock WRX bar. Most of the advice that I've run across has been to upgrade the rear bar to the STi bar for about $70, plus replace the sway bar bushings along with the bar itself. The stock endlinks are fine for this sized bar.

    Other advice has been to upgrade the front to 24mm and the rear to 22mm, along with stronger endlinks, but that advice is typically given for folks who are really interested in tracking their car or who regularly drive spiritedly on a daily basis.

    Anything larger than that is a waste, in the opinion of many "experts" on this forum. My 2014 WRX is still stock, but my hope is to upgrade the rear sway bar to an OEM STi 19mm this summer. The only drawback is that you might see a bit of oversteer if you really hit the corners hard. But otherwise it is considered by many to be an easy, cheap upgrade for the WRX in terms of cost and handling.

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    The general advice is again generally to replace both sway bars, but I don't think just putting a 19mm on the rear will add some crazy amount of oversteer.

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by Drew_V
    Honestly, I've read a TON of posts on this subject and I've never, ever, heard of this advice. 100% of the advice given on this forum so far has been to upgrade the REAR sway bar first. The OEM STi sway bar is 19mm compared to 16mm for the stock WRX bar. Most of the advice that I've run across has been to upgrade the rear bar to the STi bar for about $70, plus replace the sway bar bushings along with the bar itself. The stock endlinks are fine for this sized bar.

    Other advice has been to upgrade the front to 24mm and the rear to 22mm, along with stronger endlinks, but that advice is typically given for folks who are really interested in tracking their car or who regularly drive spiritedly on a daily basis.

    Anything larger than that is a waste, in the opinion of many "experts" on this forum. My 2014 WRX is still stock, but my hope is to upgrade the rear sway bar to an OEM STi 19mm this summer. The only drawback is that you might see a bit of oversteer if you really hit the corners hard. But otherwise it is considered by many to be an easy, cheap upgrade for the WRX in terms of cost and handling.
    I am not new to this forum, nor new to giving advice...I have given this same advice more than once or twice

    In very general terms:
    Adding a larger rear bar will cause the car to become more "neutral" in terms of the handling characteristics because the rear will step out easier. However, that doesn't address the true issue of understeer in which the front end has less grip than the rear as you enter a corner; it's just masking it by reducing rear grip. By increasing the front bar stiffness, you are making the front end "push" less, and therefore, making the car more neutral, and reducing understeer.
    Last edited by EJ257; 03-06-2014 at 06:06 PM.
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    Quote Originally Posted by EJ257 View Post
    I am not new to this forum, nor new to giving advice...I have given this same advice more than once or twice
    I have seen your handle on this forum a lot and I realize you offer good advice in general. However, I also note that most of the advice given is centered around upgrading the rear sway bar first. It is interesting to read that the rear upgrade just "covers up" the lack of grip caused by the front sway bar, but it seems that there is a "balance" between the front and rear sways in general. In the stock configuration, the rear is so much smaller than the front that the understeer is more evident. This can also be a consequence of the stock alignment. But for a "single upgrade", it seems that without changing the alignment, upgrading the rear has more effect than the front in neutralizing the handling. I don't disagree that there may be other issues in the stock OEM setup, but for simplicity it seems that by upgrading the rear sway to the STi OEM 19mm size can both improve the handling and cover up the stock setup issue as well. Just by increasing the stiffness of the front bar doesn't seem to alter the factory understeer. Frankly, stiffening the front end seems like it would make it worse.

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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by Drew_V
    I have seen your handle on this forum a lot and I realize you offer good advice in general. However, I also note that most of the advice given is centered around upgrading the rear sway bar first. It is interesting to read that the rear upgrade just "covers up" the lack of grip caused by the front sway bar, but it seems that there is a "balance" between the front and rear sways in general. In the stock configuration, the rear is so much smaller than the front that the understeer is more evident. This can also be a consequence of the stock alignment. But for a "single upgrade", it seems that without changing the alignment, upgrading the rear has more effect than the front in neutralizing the handling. I don't disagree that there may be other issues in the stock OEM setup, but for simplicity it seems that by upgrading the rear sway to the STi OEM 19mm size can both improve the handling and cover up the stock setup issue as well. Just by increasing the stiffness of the front bar doesn't seem to alter the factory understeer. Frankly, stiffening the front end seems like it would make it worse.
    A swaybar reduces body roll (hence the alternative name of "anti-roll bar").

    As you brought up, the alignment is part of the problem. From the factory, Subarus typically run 1+ more negative camber in the rear vs the front. Pair that alignment with suspension components used, and it's no wonder that Subarus are notorious for understeer.

    Subaru uses a front MacPherson strut setup. As a result, body roll causes significant camber loss when you enter a corner. So, as the weight shifts to the outside of the turn, the camber up front goes towards zero / positive. By increasing the front swaybar stiffness, you decrease the dynamic camber curve of the MacPherson strut; therefore, you will maintain more contact patch through the corner, and as a result, more grip. Where your initial issue was that the front end had less grip than the rear, you're making the car more neutral by increasing the amount of front grip.

    By increasing the rear swaybar, you are reducing the rear traction. So, again, where your initial issue was the front had less grip than the rear, you're making the car more neutral by reducing the rear grip to match that of the front.



    C/N: We're both in agreement that a larger rear bar will make the car more neutral in handling; however, it does it for the exact opposite reason that the front bar does. Therefore, why would you address a lack of grip in the front by adding a part that only affects grip in the rear? Feel free to modify your car as you please, but basically, all you're doing is making both front and rear run a wider line than necessary.
    Last edited by EJ257; 03-06-2014 at 08:27 PM.
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    That is definitely interesting. I wonder where the limitations are. That is, if the front suffers from a lack of grip, wouldn't the best "first mod" be to simply get a better alignment? Maybe it's not possible to get enough camber up front to make a difference, who knows.

    I'm curious why the consensus seems to be to upgrade the rear sway bar if all it actually does is increase rear slippage. I just read through Unabomber's manifesto and some of the other sway bar FAQ pages and they are very comprehensive and describe exactly what you are saying about the front sway bar and increased grip through less camber loss and less CG shift up front.

    I think maybe the reason people feel that their performance is improved by upgrading the rear bar is that there is less body roll, giving the illusion of better handling, whereas all they really did is trade one problem for another. Granted, improving the vehicle "feel" can be considered an upgrade in handling, regardless of actual performance gains. With less body roll in the rear, the car might just "feel" better to most people and that makes them happy. Nothing wrong with that approach, either.

  12. #11
    MAINEiac 11blackSTi's Avatar
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    Quote Originally Posted by Drew_V View Post
    That is definitely interesting. I wonder where the limitations are. That is, if the front suffers from a lack of grip, wouldn't the best "first mod" be to simply get a better alignment?
    Yes...Very much so. That and better tires.

    It's possible and very much worth it to max out the camber up front and it makes a very big difference.

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