Chassis Brace Priority
 

To some of you this may be redundant, to others blasphemy, and to hopefully a few of you some exciting news. But we felt that this section of modifications seems to be the path less traveled. We really hope this strikes a chord with you all because it seems that FRS/BRZ owners are truely in love with suspension theory and tuning. We challenge you to read and think about this. Wed love to have an open minded and positive conversation about the effects of chassis braces and answer any questions you all may have regarding this black art.

WHY CHASSIS BRACES?

Chassis Braces are the most overlooked part of building a performance car. People will buy an intake then exhaust then coilovers when they begin the process of modifying their car. Chassis Braces are viewed as the last piece of the puzzle or a "bonus part." This logic has some flaws in it however. Chassis braces provide the best "bang for your buck" when attempting to extract everything out of your ride! These parts shore up deficits in the stock platform and don't impact the drive-ability of the car. Not only do they make the car a more stable platform to work on, but the price is in competition with an intake. Now you may say, "yeah but I want a little more power and braces don't add any horsepower or torque!" By having a unified chassis you are able to put more power down to the ground! These products help extract every ounce of power by making sure none is lost in chassis slop, wheel hop, or flex. When you think about an intake giving you only a few horsepower but compromising engine reliability, leaning out AFR's, and negatively affecting drive-ability why would this be the FIRST modification to chose? The same can be said for exhaust. It seems counterproductive. By contrast installing a full set of braces will not only improve handling, and drag times, but also make it easier to learn how to drive your car to the best of its ability. If the chassis becomes more predictable you will have an easier time taking your car to its limits because you will have a more tangible limit. We don't modify cars for the sake of adding parts to car, we modify cars to fix problems in the car. In today's world of advanced 4 cylinder designs factory intake and exhaust systems are refined so far that its hard to extract any more power out of them without removing emissions control devices, yet the factory chassis is as weak as ever!

For example we personally have had a bone stock ford fiesta with only braces on it go out on an autocross course(his first time at a track mind you) and beat turbo miatas, Evos, Stis, and a myriad of other "better" platforms that were extensively modified. :confused0068: He actually laid down one of the fastest times for the day. There is a reason why chassis braces have such an impact on what class your car runs in autocross events.

http://www.ft86club.com/forums/showthread.php?t=44360

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[ame="http://www.youtube.com/watch?v=n8400qUXT68&feature=c4-overview&list=UUqrsh8Wh-lJ3bXT4TE3-oOw"]http://www.youtube.com/watch?v=n8400qUXT68&feature=c4-overview&list=UUqrsh8Wh-lJ3bXT4TE3-oOw[/ame]

Perhaps the Fiesta is just _that good_? What about times before and after this magical strut brace?

So you're telling us that a total noob with no track experience beat more powerful cars with more experienced drivers all due to chassis bracing? I'm sorry, there is hyperbole then there is cynicism.

Good call.

I've got a couple questions for you

What engineering goes into the design of the chassis braces? Do you perform an analysis of the structure and target specific weak points? Are there common areas that often need bracing? How do you determine the strength and shape of the required braces?

I'm all on board with the principle that a couple cleverly located braces could really stiffen up a chassis, but I'm skeptical what research, analysis, and testing went into most aftermarket braces. Adding braces costs money, and even for enthusiasts who want perfection at any expense, adding braces costs weight. I think you'd probably agree with me that there's a point of diminishing returns, after which improved handling due to chassis stiffness is more than offset by increased weight. That's why nobody is welding a steel plate between the subframes.

So my question to you is essentially this - what analysis or testing do you conduct to make a brace "buy it's way onto the car" - provide a net benefit by increasing stiffness and adding weight. I'm sure there's plenty of possible braces someone could come up with that don't meet that criteria - the structure they're bracing is stiff enough already that the weight hurts performance more than the stiffness improves performance. What process do you undergo to isolate the weakest areas in the factory chassis, that would have the most to gain from a brace, and ignore the areas in the factory chassis that are stiff enough already?

^ Of course this is the response you get...

A purpose built tube chassis car is essential just a web of what we consider chassis braces on an oem car. All cars flex and bend in the same ways and you can fix that a little by connecting certain existing bolt holes together.

Same concept as roll cages. All cages have the same basic design with a few edits to fit the specific car. Would you think a car body is "tested for weakness" by a cage builder?

Maybe the fiesta analogy was a bit more than what most people want to hear, but the concept and facts about chassis reinforcement is legit. :)

These cars respond great to braces. Its not rocket science to look at the car and decide where thrust forces are applied and where improvements can be made. Computer modeling and stress analysis is great but not possible for every shop. There are other more practical ways to determine the effectiveness of a component.

The chassis can be called the fifth spring and can be "tuned" just like the traditional springs at each corner.

If anyone else have driven a car with a proper 8 point roll cage in it thats a great example of a stiff chassis. With a full cage the added stiffness is really a perk since the main design is focused on safety.

Nalc, my post wasn't aimed towards you personally. Just the overall negative response immediately.

Also track times aren't always the end all measure if a part works. I know I try to time my laps at track days but its hard because Im always interacting with other cars on track so that gets reflected in the times thus skewing the data.

Rule books are a good indication of what has been proven to make a car faster. Look at autoX rule book, additional braces will bump you up a class, simple.

I wonder why nobody has ever shown test / results of chassis brake working, I mean on a mechanical level. You could simple design a brace that meets in the middle (not attached to one another) put up a camera and record how much torsion the chassis gets by looking at how far the braces flexes apart from each other during a track / auto-x run.

That would make a good demonstration for your case. I personally hate speculation and love test data.
I made a photoshop to show what I mean.

I have seen a Cusco video like that. I think they left it unbolted where the brace met the nount on one side. It was in Japanese.

I understand, I'm just wondering if there's any proof or evidence of improvement, because practically every mod has a "zomg the mod made the car a bazillion times better" review on a forum. I work in aviation, and "Let's throw weight at it without doing any testing or analysis, based on what looks like it's weak" is some amateur crap. I'm not saying that I expect a little shop to be able to do a finite element analysis, or put strain gauges all over the car, but I would expect them to develop a brace based on looking at parts of the chassis that look weak and previous experience with other cars, then do at least some sort of before-and-after road or track test to confirm that the car actually benefits from the brace. There's probably a number of weak points in the chassis that are designed to be weak because they don't see a lot of load or stress on them, and that wouldn't benefit from bracing. I'm sure there's a number of weak points in the chassis that were either a design oversight, a cost-cutting measure, or a ride comfort compromise that will see big performance gains from braces. How you tell the two apart is the key. Otherwise you're just paying $$$ for a pretty piece of metal that may not be doing anything worthwhile.

You wouldn't want to do it that way, unless the bars are carefully balanced and very rigid, there will be vibration, and you won't get a worthwhile measurement. Better to just fab up a bar and slap a strain gauge on it, then watch what it does. If you get some strain on the bar, it's working, and reacting loads. No strain on the bar, it's just sitting there, looking pretty, costing you weight and money. It's proven technique, and strain gauges are cheap.

Yeah I have seen a few companies do this, I think its a great real world demonstration.

I see where you are coming from with doing complete R&D. However all of those R&D hours will be reflected in the final price so there has to be a balance of data and whats realistic.

Look at how F1 cars are developed, massive budget and mega software. Then once its physically built they still coat it with paint and take it for a spin to see if it actually does what the computer says it will.