I get the action of sway bars, but I don't necessarily understand what strut braces do for me. I hear people saying "They tighten up your suspension," but how?. I guess I'm looking for an overly technical explanation. Thanks.

 

I would have to say it reduces your body flex by tying your strut towers together. Sorry not very technical but I'm sure others will chime in with that.

 

It stiffens your chassis which will reduce the tendacy of your car to deform underload. Of course the RX8 already has a very stiff chassis so I don't know what strut bars will do in this case.

Anti-sway bars on the other hand, helps in weight transfer. That will definitely help the 8.

Not very technical, hope it helps

 

I've always wondered just how much effect these have on the street, or is this is just window dressing.

One of the most hilarious things I've seen in "Ricedom" are REAR strut braces on Civics- how much deflection do these guys think they get with a 100 inch wheelbase? Especially with all that cornering power!!!

 

I think of it this way, the springiness on the car should come from the springs not the chassis. You want the chassis to act like a mechanical ground. Of course in real life, the chassis will deflect no matter how stiff, you just want that deflection to be as close to zero as possible.

 

my understanding is that it helps keep the strut towers parallel to one another (minimizing deflection).

the idea is to keep the strut towers like this:
| |

istead of like this:
| / or \ |

i've noticed that while most bars are soild there are some on the market that have hinges. i haven't quite figured out why that's a good idea because it seems to me that would cause the frame to become a parallelogram under load when the idea is to keep it square.

Ray

 

Like others have said, they are to stiffen the chassis. Regardless of how stiff a chassis is, they will flex. The intent is to make it so they flex as little as possible. Even race car chassis flex, to a point. I'm going to try to keep this short, but if anyone needs me to explain something in detail, I can.

First of all, think about how fine the tolerances are when a car is aligned. They measure down to a few tenths of a degree. In a sports car, it really makes a difference in handling and feel. When a chassis flexes, your alignment basically goes out of whack. The stiffer the chassis, the better it will keep the alignment.

Second, a spring and sway bar flexes in a very consistent manner. A chassis does not. Remember, in handling, you want to keep the chassis stable, and have that optimum tire contact patch. When the chassis flexes in an inconsistent fashion, it's like having a bad shock, the tire does not keep that consistent patch, and handling suffers. The more you can keep flex out of the inconsistent chassis, and into the consistent suspension, the better handling will be.

A side effect of chassis flex is a harsh and noisy ride. Stiffening the chassis actually noticeably improves the ride. That's why someone just driving down the street to get groceries can actually feel a difference when putting on an effective strut tower bar.

One thing to remember is that triangles are strong, squares are weak. When you add a simple tower-to-tower bar, you are creating a square (the other sides being the fenders, and the base of the windshield). When you corner, or only hit a big bump on one side, that square will twist (like a parallelogram, like GTRay mentioned). Adding a diagonal brace will create triangles, and will make a big difference.

As far as hinges on a STB, you have to remember that all you are trying to do with a simple STB is tie in the two strut towers. The forces are pushing or pulling on that bar, and a hinge will not affect those forces.

One thing to consider is when you add stiffer springs, shocks, sway bars, or bushings, those stiffer items will deflect more energy into the chassis, making it flex more. Part of the harsher ride that you get from stiffer springs and/or shocks is because the chassis is flexing more. When you stiffen the chassis (and that normally means more than a simple tower-to-tower brace), you can actually eliminate alot of the harshness of a stiffer suspension, and you can also minimize other negative affects of a stiffer suspension on street surfaces, improving handling. This is something that is lost on alot of "tuners", and why people like me can put Tein HAs (very stiff) on a street car, drop it two inches, but actually get it to ride better than stock.

---jps

 

Thanks sputnik and everybody else...that's what I was looking for...now I just have to go buy one :D the question is, $750 for the AutoEXE front and rear package (both of them four point), or $350 for the CP Racing 4 Pt front and the Mazdaspeed 2 point rear...hmmmm...

 

I have the MazdaSpeed strut braces and sway and I don't think it get any noiser... it certainly stiffen up the car to a degree that any owner drive my car can feel the difference... very noticable and highly recommanded

 

Is there a picture of the AutoEXE rear 4-point bar?

---jps

 

Taka to the rescue

Sputnik ... found the site you may be interested..

http://www.autoexe.co.jp/car/se02/go...eikakusei.html

Edit: translate it with translator from altavista.com bubblefish

It looks very good - I like this under car brace more than the MazdaSpeed version

 

here ya go

 

Thanks guys.

Those look very nice. No flashy crap, just straight ahead engineering. I especially like the underbody bracing. The tranny tunnels form a shape of a U, and a U shape is weaker than a square, so "boxing" the tranny tunnel like that (and just as importantly, tying in the mount points of these braces very close to other suspension mounting points) is also effective. If you've ever ridden in stock '99/'00 and stock '01 and up Miatas back-to-back, a big difference in the "solid" feel of the '01s is the tranny tunnel bracing that was added.

These are braces that I would seriously look into going the expense of importing, or having custom made. The next step after this would be a roll bar or roll cage, and depending on the car and the items, that can really restrict the use of the car.

---jps

 

The under braces look like they might be a pain in the **** if you had to do any work under the car...hopefully they would be easy to remove if needed...only another $750 or so for the brace set :D

 

Yes they are mighty easy to be removed... a hand with a 14mm spanner. :D

They are not hard to install either but need a proper jack (as in the garages) to go underneath to tighten the screw properly. Would not do it with 2 jacks.

Taka