Reason/Answer for bent rear sway bar brackets

So today I got the chance to work on Crazy_Ken's 05 GT. When I was working the car, and I have worked on it in the past, we came up to talking about the Perrin brackets and such. Long story short, here are the specs on the car:

50,000 miles

STi Pink Springs (close to 30,000+ miles logged on)

Stock Shocks

Cusco Vacanza Rear Sway 21mm bar (installed just 1000 miles after the springs) [set to full stiff]

Cusco Endlinks

Cusco Under Braces

Prodrive GC-6 18x7.5 wheels

Toyo T1-S 225/40/18 tires (for a good portion of 20,000 miles)

While we were working on the brakes, we noticed the brackets for the RSB didnt break off like ones that you see posted on other threads or whatever the previous cases you see here, but rather bent backwards on one side and the other side was helically twisted.. this lead me to believe that with the shocks being the weak point along with soft springs and a LONG suspension travel is the culprit of the issue.. So even a cusco bar would end up bending a bracket..

Subaru did have poor design when it came to the mounting points for the RSB compared to the Impreza body. I dont know why they would skimp out on such a design. I can understand when looking at the stock RSB bar that it wouldnt bend because the size of the stock USDM bar is thinner than a pencil. Im not sure how/what the effects are when mated to a 20mm JDM bar on a USDM car, but my guess is that due to the USDM Legacy with long-travel softer springs [than the JDM GT] and soft long travel shocks [compared to the JDM GT] puts a lot of torque and forces on the bar, causing the bracket to bend. With so much suspension travel, that's basically an easy way to ask a stiffer bar to end up tweaking/torquing the crap out of the brackets.. and the way they bent, I would think even the Perrin or Cobb reinforcement brackets would need to be way more intricate to make it to keep the bar from bending the brackets.. I would really think that a new support bracket needs to not only eliminate 2 axis, but really 3 to 5 axis forces to make sure that it keeps the location of the mounts really IN place when driven hard.

I havent checked up my own car to confirm my findings, but if I see that I dont have bent brackets, then I'll know why. I also run the same sway bar and on the same full stiff setting as Ken but I run on stock endlinks and I use stickier tires and stiffer shocks and springs. I have about the same amount of miles on the car, if not, more than Ken does. I also track my car and drive it way harder than Ken (since Ken hasnt autoxed or tracked his car and doesnt plan on that either). I run on Zeal coilovers that really have shorter suspension travel and not to mention way stiffer springs than a set of STi Pink springs, so my springs can take on the majority of the road handling and keeping the sway bar as only a supplemental portion of the suspension function. It's too bad that I didnt take pictures of the sway bar brackets on Ken's car so I can show you what it looks like, but in my opinion, it's not too bad, but I really do think it does affect the performance of the sway bar's function a significant amount if it was driven on the track, I doubt a normal daily street driver would even notice it.

Stay tuned, I will post up my own car's findings some time this week (as my car is in the shop for tranny work testing).

Edit: my car does NOT have bent brackets, therefore we need to narrow it down to the primary suspension components.. Im too scared right now to go back to stock shocks with springs to do a test

JDM cars have different mounts for rsb - the JDM bars fit, but JDM reinforcement brackets not!

Possibly JDM are better/stronger, or just good enough for 20mm.

It amazes me how many differences are there between JDM and USDM. Is it really worthwhile to spend money for two designs?

Totally makes sense to me.

Stiffer suspension puts waaaay less stress on the bracket, but a normal modded street suspension (springs, and maybe shocks) causes a RSB to really work hard.

Sure, engine, suspension, perfectly understood. But lots other tid bits, like wiring, or the afforementioned bar mounting points - makes little sense.

Similarily separate parts for metric/US units display - more parts to design/stock etc certainly does not drive cost down.

Totally makes sense to me.

 

Stiffer primary-function suspension puts waaaay less stress on the bracket, but a normal modded street suspension (springs, and maybe shocks) causes a RSB to really work hard.

fixed

fixed

My own persoanl secretary, thanks, better written!

Nope.. I examined the mechanics involved and I have come to the following conclusions:

1. Stock endlinks are the highest quality around - if you don't rip them apart they will outlast everything else, and do so quietly.

2. The rear bracket should have very minimal force put on it by the sway bar. The reason it rips apart on aftermarket sway bars (and not even the JDM bar) is because of poorly designed bars and endlinks. It's obvious that 9/10 aftermarket companies can't master the mechanics behind making the double linkage mechanism work properly. Force is transmitted to the brackets basically when the design of the sway bar and endlinks causes the assembly to run out of movement, it binds either by the endlinks binding themselves (all aftermarket endlinks are not sealed) or because mechanically it's in the wrong position. Now this is complex, but most even slightly mechanically inclined people can see the fact that the aftermarket bars put the endlinks at a bad angle and rip them apart, well before it rips it apart guess what, it's transmitting force to the sway bar mounts.. (tiny little 12mm nuts/bolts, does it look like it's meant to take force?) Stronger endlinks are the wrong solution... But this is what you get for redneck engineering on the bars..

Deer Killer, the reason why I am posting this is because I am trying to tell you about your "2" remark.

Cusco makes a lot of very good parts, and their sway bars are one of the best fitting ones. Even the better designed bars are bending the brackets. That's what this whole thread is about. Im trying to isolate the problem that it's not only a sway bar design problem (maybe they are design correctly), but a bigger picture that the shocks and springs are bending the brackets because the bar is that much stiff (less deflection). It's not about the LACK of movement as I am stating, it's VAST amount of movement (aka torque force x distance/shock travel).. if/when properly design, the bolts of the endlinks aren't suppose to be affected by the forces. My point is that the leverage and force applied ONTO the bar is far greater than just breaking an endlink, it's bending the bracket.

My input:

JDM rear bracket is only different in the bolt hole locations. You could take our rear bracket and drill out the difference. Otherwise identicle.

My mounts were bent already, even though I've had the standard OEM JDM bar in the rear. And I wager quite a few JDM car owners have at least slightly bent the rear mounts by now.

Now, I'm not really trying to sell our product here, because this applies to anybodies rear mount bracket reinforcements. And I can say with confidence that you would likely feel the difference on the street with some sort of reinforcement back there. Hell, I've of mind to weld the reinforcement to the standard mount. The standard mount is really just way too weak.

Cheers,

Paul Hansen

http://www.avoturboworld.com

...now for my main question...What do I do about it???

Bend it back

Bend back and reinforce it

Change Springs

add better struts

get better tires (wider)

coilovers

Thanks,

CRAZY KEN

My input:

 

JDM rear bracket is only different in the bolt hole locations. You could take our rear bracket and drill out the difference. Otherwise identicle.

 

My mounts were bent already, even though I've had the standard OEM JDM bar in the rear. And I wager quite a few JDM car owners have at least slightly bent the rear mounts by now.

 

Now, I'm not really trying to sell our product here, because this applies to anybodies rear mount bracket reinforcements. And I can say with confidence that you would likely feel the difference on the street with some sort of reinforcement back there. Hell, I've of mind to weld the reinforcement to the standard mount. The standard mount is really just way too weak.

 

Cheers,

 

Paul Hansen

www.avoturboworld.com

Do you have brackets that fit USDM? I know this is hard to answer but, are yours as good as Cobbs or better? I'm ready to buy reinforcement but I have not heard which is better?

They should be in a container to us right now! (crosses fingers...)

And of course our are better! What a silly question! :D

Cheers,

Paul Hansen

http://www.avoturboworld.com

Do you have brackets that fit USDM? I know this is hard to answer but, are yours as good as Cobbs or better? I'm ready to buy reinforcement but I have not heard which is better?

Hey Itsme,

I think this is the new AVO Stabilizer Bar Mounts that Paul is talking about (correct me if I'm wrong Paul ) -

http://www.avoturboworld.com/content/view/47/31/

Yah, I'm curious if this would help.

I think the problem lies more so in the geometry of the aftermarket bar than it does with the size or suspension setup. For those that had a B5 Audi (S4/A4) might recall a rash of problems with a swaybar set on stiff shearing the rear mount points for the bar. I believe it was only one vendors bar that was actually causing the shearing, however other bars were reporting bending issues. The difference between the manufacturers was one of size (20mm vs 18mm) and geometry of operation as one was adjustable for increased stiffness. Judging that the one with most notable issues was more adjustable than the othes, I'd guess MOST of the problems lie in the geometry. However the company did create a stop-gap fix and is producing reinfocing brackets to brace the stock mounting points.

...now for my main question...What do I do about it???

 

Bend it back

Bend back and reinforce it

Change Springs

add better struts

get better tires (wider)

coilovers

 

Thanks,

 

CRAZY KEN

MY honest opinion is bend it back and reinforce it.

I think I will be looking for something better of a design for a bracket once I get my car back from the shop.. (been procrastinating about picking it up). It's probably way better off to come up with something really thick and large for the sway bar brackets.. the problem with the design with the stock mounting locations is that there's too many leverage points (distance) which is putting the real stress on the brackets. If you can minimize the distance of the suspension (and distance I mean you can shorten the suspension travel) that would help out greatly.

The best thing to do at this point is to bend the stock brackets into place and install the reinforcement brackets. I may just go with a custom reinforcement bracket that holds up in 3 different axial movement and not just 2.

I think I will be looking for something better of a design for a bracket once I get my car back from the shop.. (been procrastinating about picking it up). It's probably way better off to come up with something really thick and large for the sway bar brackets.. the problem with the design with the stock mounting locations is that there's too many leverage points (distance) which is putting the real stress on the brackets. If you can minimize the distance of the suspension (and distance I mean you can shorten the suspension travel) that would help out greatly.

 

The best thing to do at this point is to bend the stock brackets into place and install the reinforcement brackets. I may just go with a custom reinforcement bracket that holds up in 3 different axial movement and not just 2.

after you get it perfected start selling them after you made one it's easy to make a hundred. just a thought. bosco

...can Andrew whip up something???

I am really interested in doing something...you remember I said there was a delay reaction to the grip of my car in hard turn...could this also be a reason? Beside needing new tires and a alignment! That's next on my list!

CRAZY KEN

BTW, should I be concerned about the front swaybar as well?