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View Full Version : How much stiffness could this chassis brace add?



winchman
07-01-2010, 02:46 AM
What do you think of this thing?

"GTSPEC 4pt mid brace. Made in 6061 air craft grade aluminum with triple internal hallow wall."

http://www.corsportusa.com/store/catalog/images/350z-mid.jpg

I have no idea what "triple internal hallow wall" means, but I think it really would have to be holy to add much stiffness.

Even if it were made of steel, I think I could move one corner some by hand with the other three bolted down.

NzOldun
07-01-2010, 05:37 AM
If it comes from the actual vehicle manufacturer, then it's probably ok.

If its 'after market' then watch out!!

You would need some fancy heavy duty Finite Element software and very reliable and detailed info of the vehicle floor pan and sills and the materials of construction, to analyze the behaviour, both in the before and after state, to really get a satisfactory answer - and probably three to four of weeks of a professional analysts time. At a rough (very) guess about $25-35K

NZoldun

Evan
07-01-2010, 05:38 AM
The word scam comes to mind but perhaps that is a bit to strong. After all, even if you made it from triple blessed cardboard it would add some stiffness.

John Stevenson
07-01-2010, 05:45 AM
Should have been made from billet :D

In fact a big alloy plate would probably be stiffer

Doc Nickel
07-01-2010, 06:07 AM
I have no idea what "triple internal hallow wall" means[...]

-Just a guess, but maybe something like the flat tubing had internal walls/ribs molded in as it was extruded? A sort of chambered pipe?


[...] but I think it really would have to be holy to add much stiffness.

-I don't know the precise method by which it works, but I know that on older cars, like early Camaros and certain Mopar musclecars, add-on rails called "subframe connectors" did, in fact, make a considerable and measurable difference in the car's stiffness.

The affected cars had a subframe rather than a full ladder frame- meaning the front suspension, engine and transmission were supported by a true frame, but one that ended before the rear suspension, which was hung off the body, which in turn was a sort of semi-unibody arrangement.

The connectors joined the two more rigidly, and significantly reduced twist.

Now, how that concept would work on a more modern unibody car like the one shown, or how well that kind of four-point bolt-on frame would do the same thing, I have no idea.

Subframe connectors could be easily "tested" just by jacking the car up from one side, before and after. Presumably you could do something similar with this, to see what the difference was.

Doc.

Evan
07-01-2010, 06:18 AM
The frame shown is weakest in twist with practically no strength at all in that axis. It's a big tuning fork. A U shape has no significant rigidity in any axis.

Arcane
07-01-2010, 06:27 AM
I went looking for a price for that thing, the first site I found had it for $343.99 but they did say theirs was "Military-Grade 6061 Aluminum". :D I believe it falls into that special catagory of "must have" items for people who have more money than brains...called GewGaws. It probably does stiffen up the chassis a bit but $343.99 worth (plus taxes)? Looks like its primary purpose is to transfer money from "your" account to "their" account.

Farbmeister
07-01-2010, 06:53 AM
They found some empty bolt holes on the tub and made a bracket for them??

maybe if it was preloaded somehow? Looks more like a drive shaft keeper (whatever they are called) than a frame stiffner.

dvbydt
07-01-2010, 07:14 AM
Very usefull, it would stop the exhaust pipes dragging on the ground if they came loose.:D

IanR

gda
07-01-2010, 07:47 AM
This reminds me of the people with the jacked up trucks that run out of spaces to mount shocks with the boots and start to mount them horizontally over the rear leaf springs.

+1 on the jack up the corner of the car for before and after measurements.

Rustybolt
07-01-2010, 07:58 AM
They found some empty bolt holes on the tub and made a bracket for them??

maybe if it was preloaded somehow? Looks more like a drive shaft keeper (whatever they are called) than a frame stiffner.


We have a winner!

J Tiers
07-01-2010, 08:37 AM
The floor pan would normally have the most stiffness in the same horizontal plane that the "brace" has whatever nominal stiffness it has......

Except that the floor pan is dished up , which effectively makes it into two half-floor pans for some forces..... About all that brace does is to partially tie together the two "half pans" across the dished section, and it does that in only one area.

IMO that is some very expensive scrap...... I don't think it could even trap the driveshaft.

daved20319
07-01-2010, 08:55 AM
Designed to catch fisherman rather than fish :-). That thing looks cool and high tech, so it MUST do SOMETHING, right? I got interested in suspension tuning for awhile, took the time to learn something about it. What little I managed to absorb tells me that's virtually useless as a way to stiffen the chassis. Like someone already said, a solid plate would be far more effective. But it does look cool :-). Later.

Dave

Rattrap
07-01-2010, 09:19 AM
I suspect the designer/seller sees it as the under-chassis equivalent/complement to the shock tower brace. Or at least hopes that buyers will. ;)

Brett Hurt
07-01-2010, 10:13 AM
I have a scion xb and I put one on by tanbe and it works great . Helps a lot at high speed. do it get one off ebay I did. To go all the way I would do the front end and rear end then a stut bar for it. Then it will run like a mini copper in the corners . Brett

Evan
07-01-2010, 10:36 AM
Sorry, but that shape simply has no inherent rigidity. Even the triangulation braces serve no purpose as they don't extend to the mounting points. Any of the ends such as the shorter cross brace that end in the middle of another brace do nothing at all except to weaken the structure because of the destruction of the properties in the heat affected zone by welding. If all the welds were at the mounting points only that would be far less important. I would bet that with the leverage available that If I clamped one end in a vise I could permanently deform it by hand.

No matter how many braces are used or where they terminate that shape is weaker than a flat plate of the same size. A flat plate has practically zero strength in 2 out of three axes and the third is subject to easy buckling.

kendall
07-01-2010, 11:21 AM
It's mostly hype and flash.

It might help to stiffen up a chassis that already had a cage, but alone it's just space filler.

My old mustang used to twist enough that I was always adjusting the doors. I had to install a full cage that tied the rear suspension to the front, fully braced and triangulated. Which I wanted to avoid because I wanted a stock look. (lost that battle)

Ken.

MuellerNick
07-01-2010, 11:32 AM
It is anodized in racing blue. It MUST be good!

And it really looks impressive. After a rollover.:D


Nick

RancherBill
07-01-2010, 11:58 AM
I am not an automotive engineer.

It looks like it is part of a system for A Nissan 350 Zed (http://www.gtspec.com/catalog/products-car/nissan/2003-2008-350z):) It will probably also work on the American Zee models.:D

My son had a Chev Cavalier that he made into a cool car. He did the research and got the parts. I had drove the car before and after. What a huge difference. We/he had installed shock tower mounts, both front and rear, along with a mid frame stiffener. He sourced the parts from a forum and when they arrrived they were very low tech. IIFR they were 1" x1/8 square tube with mig weld plates on the end.

It went from a family car to a bone jarring performance vehicle that could go around corners without bodysway and the steering wandering. I actually had second thoughts about it after driving it as I knew he would be going faster than his skill set.

I'd go for it. Having seen the Cavaier parts I'd even weld up my own. Looking at the pics, there is enough detail to reverse engineer the parts unless you are going to put a turbo on the engine and go at silly speeds.
________
Bodywork was done by someone else, he/we did the engine and suspension. Not your normal Cavalier.

http://i294.photobucket.com/albums/mm100/rancherbill/dianescar002.jpg

Black_Moons
07-01-2010, 12:51 PM
Not an engineer or car euthist... But I must say that brace does look awsome, Id likey fall for it.. if I had a reason to think my chassie needed to be stiffer... And could be assed to do even minor maintence on my truck, like fixing the temp guage...

I do know that entire cars *do* bend, some cars moreso then others..

that brace may not be so much to improve stiffness on its own, but to limit those mounting points from changeing distance to eachother, as would occure if the entire frame started to twist or bow/bend.


I think evan even did a demo recently of how a C channel is FAR easyer to twist then a box. Well, that body kinda looks like a C channel with the cutout for the drive shaft...

the middle cross bar looks like it was placed wayyy too far back.
Maybe its like that for exhuast/ground clearance issues.. but it seems it would be much stronger placed at the other end.

And while a plate might be stronger, A plate is not gonna be *lighter*
Though I must admit, even with tripple whatever wall aluminum.. that does not look like a very strong bar that will stop much more then forces in tension..

ADGO_Racing
07-01-2010, 01:28 PM
Part of what we do here is build chassis for real race cars, asphalt modifieds and late models. The brace in question will, to some extent will stiffen the chassis. More so in the cross direction (e.g. LF wheel to RR wheel and RF wheel to LR Wheel). If you are looking for torsional stiffness, this is NOT going to do the job.

Torsional stiffness is accomplished through the roll cage. We have tubes that come up from the left rear sub frame to the rear cross bar of the roll cage. There is a tube through the cockpit to the lower right "A" post of the roll cage. If the rules allow we will continue that tube to the right front frame horns. When viewed from the side this forms a big triangle. Viewed from above, it is at an angle from the LR to the RF. This stiffens against the chassis twisting during cornering (since we are always turning left). We also use some tubes in the engine compartment, to stiffen against engine torque. To stiffen against engine torque, is a difficult chore, as there isn't much room to work with, but some imagination and it can be done. We use a full mid plate in our chassis for this purpose.

+2 on putting the chassis up on stands and attaching a lever and known weight. It will show you how much deflection you have to start with.

If your engine is making 150 ft/lb of torque, a 10' lever with a 15 pound weight at the 10' mark, will replicate what effect the engine is having on your chassis.

ADGO_Racing
07-01-2010, 01:48 PM
Take a flat sheet of paper and lift a corner, now lay a cardboard cutout of the "stiffener" and repeat the process. Yes it is a little bit stiffer, but the cardboard cutout will flex with the paper. Anything in the same plane is going to react the same way.

You must triangulate the chassis to prevent twisting. This is ok, if you plan to run it off road, such as drag racing or circle track. However, it can be a bit dangerous for street use. Street vehicles are supposed to crush in an accident, to protect you and whomever/whatever you hit. The stiffer you make the chassis, the harder the crash will be, and those forces transmitted to the driver.

Even our purpose built chassis' are built to bend at certain points, to protect the driver during a crash. Even with that, the forces it takes to bend the chassis are FAR greater than any street vehicle. (Our chassis' never see street use).

We rely a lot on the fact that there isn't really anything on the track that you can hit and come to a dead stop. Hitting another car, is kind of like playing pool. Both cars are the same mass, so it is rare that one will come to a complete stop. Hitting the wall usually takes place at an angle less than 45* (Angle of travel, not the physical car), so forces are vectors, not head on.

If it is a bone stock car, or slightly improved through common aftermarket parts, you realistically are not making enough power to worry about stiffening the chassis.

Evan
07-01-2010, 02:07 PM
I think evan even did a demo recently of how a C channel is FAR easyer to twist then a box. Well, that body kinda looks like a C channel with the cutout for the drive shaft...

The drive gear tunnel in a unibody is a huge part of the strength of the floor pan. It provides nearly all the fore/aft bending stiffness. The rest of the car body is what make the unibody a box section and provides the resistance to twisting. Any flat section or system of struts that lies all in the same plane has just about no resistance to twisting in any direction that is coplanar. The only direction it provides any stiffness is perpendicular to the plane it occupies. The brace in question even fails on that account because it is U shaped and has no effective triangulation. The short cross brace forms a trapezoid with the long brace and that is a collapsible geometry.

I have corrected the image for perspective and marked out the structure of the brace. The two yellow triangles are the only parts that are rigid in the plane the brace lies in. The red circles are all hinge points at which the struts are free to rotate in any direction restrained only by bending strength instead of tensile strength or compressive strength. Further, they are points at which the strength is greatly reduced by welding.

http://ixian.ca/pics7/brace.jpg

topct
07-01-2010, 03:03 PM
It's a replacement for the factory brace. Just made lighter and prettier.

The same company make a series of replacement under car braces.

For a street car it would be pointless. But if you were trying to save several pounds of weight in a car being set up for racing, replacing the stock parts would help. This isn't the only brace under these cars.

Also it's possible to increase the chassis stiffness from a factory made part in other instances.

saltmine
07-01-2010, 03:48 PM
I'm guessing the chassis is a unibody, late model Ford Mustang.

For some unknown reason, Mustangs have always had a chassis with the rigidity that rivals well cooked spaghetti. One of the first "fixes" most "tuners" recommend is a set of chassis braces to stiffen up the "rubber-band" underpinnings of a Mustang.

Serious racers don't even bother with the stock chassis, they build a mainframe right into the roll cage and are done with it. But, frame stiffners are "eye candy" and bragging ammunition for bench racers worldwide.

If you want something that handles...get it from the factory. Don't try to make a silk purse out of a sow's ear.

BTW, that drive shaft is a two-piece unit...a dead giveaway for a late model Mustang....That, and Ford likes to hang dampeners all over things instead of balancing components.

Reminds me of when Chevy trucks went to independent suspension in the front end of their 4 X 4's. A bunch of aftermarket hacks started offering "lift kits" for the suspension. The only problem was, you couldn't just "jack it up" because you'd destroy the suspension geometry and the driveshaft angles, so, they lifted the whole frame with bolt-on, flat steel spacers. All well & good, except the first time you went around a sharp corner too fast...then it folded up like a house of cards. They still make them, but only after some serious engineering went into a lot of corrections to keep it from bending sideways, and making the truck fall over.

oldbikerdude37
07-01-2010, 04:56 PM
Oh boy ,watch out, Even may launch an investigation and call it a scam being that he knows everything about everything.

Evan
07-01-2010, 05:12 PM
Oh boy ,watch out, Even may launch an investigation and call it a scam being that he knows everything about everything.

Impossible. For instance, I have no idea why you are a hirnlosen Holzkopf.

oldbikerdude37
07-01-2010, 05:15 PM
Impossible. For instance, I have no idea why you are a hirnlosen Holzkopf.

stick your german in your german hole berkley boy.

did you call mama and complain yet?

You are a stalker and a sick person. some weirdo like you start posting my personal info and you will have trouble.

Evan
07-01-2010, 05:18 PM
Paranoid too?

oldbikerdude37
07-01-2010, 05:19 PM
Paranoid too?


Nope just can see a weirdo when I see one.

Evan
07-01-2010, 05:32 PM
So you also think you have the power of remote viewing too? You should apply for a job at the CIA (http://web.archive.org/web/20060501072612/http:/www.parascope.com/en/articles/starGate.htm)

Tinkerer
07-01-2010, 05:34 PM
I have no idea what "triple internal hallow wall" means,
That's code for porosity... I third of the weight with a quarter of the strength. :eek:

oldbikerdude37
07-01-2010, 05:37 PM
So you also think you have the power of remote viewing too? You should apply for a job at the CIA (http://web.archive.org/web/20060501072612/http:/www.parascope.com/en/articles/starGate.htm)


You decide if I am, being you know everything.

EddyCurr
07-01-2010, 06:18 PM
I have no idea what "triple internal hallow wall" means,It may be a reference to a tube manufacturing process known as Butting.

Cyclists weigh the merits of bicycle frames on whether the tubing the frames
are constructed from is single, double, triple or even quadruple butted.
The term refers to differences in wall thickness at the ends of the tube
sections, relative to wall thickness in the center.

Reynolds has a page that give a brief overview here (http://reynoldstechnology.biz/our_materials_butted_tubing.php)

Dahon has a few remarks here (http://www.dahon.com/technology/frame-materials)

.

darryl
07-01-2010, 06:58 PM
Take an O and a Y. Stuff the Y into the O, then extrude it. Result- a triple hollow tube. Or take a square tube and stuff a V into it. Same result, a hollow tube divided into three sections. Hollow, hallow, hello- three different meanings, but the fact of that is just as worthless as the description of that tubing. Might be similar to saying, about the oil spill, that BP has an 'in depth' problem, or that a pipe company has endless tubing.

J Tiers
07-01-2010, 09:46 PM
Evan is being a little extreme... The thing does not have "no" rigidity in some directions..... It has "some" in each possible direction.

But if properly made, it could have quite a bit MORE in certain directions.

Now, the tunnel has fore and aft bending resistance, yes. But because it is only formed sheet metal, as thin as they could get away with, when it does resist such a bend, it wants to spread open.

The flat parts of the pan do resist that, but they are subject to buckling, resisted in turn by the ribs etc formed in them. The designers no doubt did extensive FEA and made sure that it was "good enough" for whatever level of vehicle they decided to classify it as.

Tieing across like that CAN reduce the tendency to spread open, and thus improve overall bending strength.

THAT particular brace is made in such a way that it "almost" does what it could.......... There is a chance, which I rate as small, that the weaknesses we are pointing at are intentional for a purpose.

I rate that as a small chance because the analysis would be expensive, and the makers probably do not have access to the level of structure detail that the carmaker has.

If one assumes that it is supposed to be useful, one might wonder how that particular piece is better than a sheet of say 0.125" or 0.187" aluminum tied across the same points.

Evan
07-01-2010, 09:56 PM
I didn't say no rigidity Jerry.

"Any flat section or system of struts that lies all in the same plane has just about no resistance to twisting in any direction that is coplanar"

Twisting is a lack of torsional rigidity in a single axis and can be very low compared to other possible deflections in a part. A flat section has rigidity to coplanar twisting that corresponds to the distance to the furthest fiber in the thickness only. In other words, if the plate is 1/4" thick the distance to the furthest fiber from the neutral axis is only .125". That is as close to nothing as you need to get. As for tensile forces due to spreading of the tunnel a few steel straps of .25 flat bar will do the job for a few bucks and a lot less weight. You could even paint them blue.

J Tiers
07-01-2010, 10:04 PM
I didn't say no rigidity Jerry.

Maybe I mis-read the following:



Sorry, but that shape simply has no inherent rigidity. Even the triangulation braces serve no purpose as they don't extend to the mounting points. Any of the ends such as the shorter cross brace that end in the middle of another brace do nothing at all except to weaken the structure because of the destruction of the properties in the heat affected zone by welding. If all the welds were at the mounting points only that would be far less important.

saltmine
07-01-2010, 10:36 PM
It's an electrical component.

It's designed to make currency flow from your wallet into the manufacturer's bank account.

Richard-TX
07-01-2010, 11:32 PM
I believe it falls into that special catagory of "must have" items for people who have more money than brains...called GewGaws.


Like putting a aftermarket exhaust system on a VW. You spend over a $1000.00 to get at most a 3% increase in peak power and lose power at the low end.

Brett Hurt
07-02-2010, 12:21 AM
A strut bar, strut brace, or strut tower brace (STB) is a mostly aftermarket car suspension accessory usually used in conjunction with MacPherson struts on monocoque or unibody chassis to provide extra stiffness between the strut towers.

With a MacPherson strut suspension system where the spring and shock absorber are combined in the one suspension unit, the entire vertical suspension load is transmitted to the top of the vehicle's strut tower, unlike a double wishbone suspension where the spring and shock absorber may share the load separately. In general terms, a strut tower in a monocoque chassis is a reinforced portion of the inner wheel well and is not necessarily directly connected to the main chassis rails. For this reason there is inherent flex within the strut towers relative to the chassis rails.

A strut bar is designed to reduce this strut tower flex by tying two parallel strut towers together. This transmits the load of each strut tower during cornering via tension and compression of the strut bar which shares the load between both towers and reduces chassis flex.

On the Saab Sonett mk2 and mk3 the overflow container for the cooling system doubles as a strut bar. The longnose version of the Saab 96 also came with a factory mounted strut bar. This despite that both cars used double wishbone suspension.

Brett Hurt
07-02-2010, 12:41 AM
Sustec Under Brace-Total Tuning for Chassis! By connecting specific points of the undercarriage of the vehicle, this under brace reinforces the strength and stability of the chassis. This under brace is also very lightweight, so it will not add much surplus weight to that of your overall vehicle.



Features
Often overlooked, especially on vehicles that are reaching higher levels of modification, is the importance of reinforcing the chassis. All vehicles experience flexing of the unibody under various handling loads. Twisting of the chassis is also very common on higher horsepower vehicles.

The Sustec Under Brace prevents this unwanted behavior by connecting specific points of the undercarriage to reinforce the chassis. Unique internal double-i-beam construction is highly rigid and lightweight, so the chassis may be significantly reinforced without adding surplus weight.

The under brace (especially when used with the strut tower bars) will further improve handling and chassis strength. Excellently constructed with a high quality design and fitment, this under brace was made to fit the 2010 Toyota Prius.
Creates the highest rigidity possible
Allows for extreme chassis flex reduction
2 Point configuration (Front)
Creates stability between the left and right side of the vehicle, which therefore improves handling.
These things work on a car That is why I have it on my scion xb

dp
07-02-2010, 01:21 AM
To my eye the brace looks like it will potato chip freely since only the corners are anchored, and the strength just isn't there to prevent racking. 6 anchor points will help, but will probably also crack the welds.

saltmine
07-02-2010, 01:30 AM
I donno guys. After being in the automotive business for almost 50 years. I figure if you buy a car that needs to have the chassis stiffened, the manufacturer built a faulty design.

I buy American, and have never had to go out and buy some razzle-dazzle chassis stiffener.




And why in the heck would you want a "Chassis stiffener" hanging under a Toyota Prius??? Aren't those things in the "zero-to-60-in-one-afternoon" class?

Evan
07-02-2010, 01:47 AM
There is nothing less reliable than an eye witness. That is a common saying in court and it applies to any situation where evidence of anything is based on purely subjective experience. If you just went out and spent hundreds of dollars for a strut brace or chassis brace you have a powerful subconscious incentive to "detect" some sort of difference that you can attribute to the new part.

They only way to really know if it makes a measurable difference is to do objective and repeatable tests that measure the flex of the chassis under load. I strongly suspect that jacking up the vehicle and attempting to measure a difference in sag at any point will be inconclusive. There isn't likely to be enough difference to measure with any degree of certainty.

I have some experience with monocoque body construction as I was in the distant past involved in racing. In the early 70's I built the entire monocoque chassis for a Can Am race car and incorporated some design changes of my own that greatly increased the rigidity and the safety of the original design while reducing the weight by 20%. The driver of the car was extremely happy with the result. I didn't get much chance to follow up the performance of the vehicle as it was just shortly after that I changed jobs to work for Xerox.

oldbikerdude37
07-02-2010, 02:05 AM
It's an electrical component.

It's designed to make currency flow from your wallet into the manufacturer's bank account.

yep, its a scam even is on the job, he will save us from everything because he knows everything.

Evan
07-02-2010, 03:50 AM
Stalking can get you banned. George does read this board.

BWS
07-02-2010, 06:37 AM
It might work,but as has been mentioned testing would be the order of the day.To wit:find a cpl donor cars and fire up the Cat,thinking forklift volley ball with the test samples would prove inconclusive.So,if you had access to a junkyard and the desire to learn.......might keep me entertained for an afternoon.

The part is in an area that I'd be wanting cheap,sledge hammer adjustability if it proved to be worth the effort.BW

airsmith282
07-02-2010, 07:10 AM
it looks like to me that its a sub frame anti sag brace, handy on old cars and would be usfull on new models as well. its no to hot on the anti twist part but its more a design for anti sag, iam not sure as if i would trust alulim for that job only cause it will tend to strech, and eventually snap, if it was made the same way but out of steel it would stand up alot better, a model that would clamp to the sub fram for the engine area would also help prevent the need for off set control arm kits on larger cars , for example the 80's models of the fith ave. car, big car but prone to fram sage expecialy up front hence the reason i mentioned the off set control arm kits that could be prevented .


iam no engineer but even i can see the flaws in this setup..

topct
07-02-2010, 10:43 AM
The cars designers felt that an additional member at this point was needed. The piece bolts on using the original mounting points for the factory item.

I am going to assume this replacement reinforcement performs the same function as the factory made one.

I'm going with the tunnel spreading comment. There is shown a short cross member under the tail of the transmission. But it looks like the engineers decided more bracing was needed.

I'm sorry this doesn't qualify as a scam. It is a real piece, made by a real factory, sold by a real company.

I would like to hear comments from a real chassis design engineer.

Falcon67
07-02-2010, 11:13 AM
IMHO - as a racer and somewhat familiar with chassis flex - it's "ricer bait". It's bolted to the front "frame rails" on a unibody car. Big deal, that area is reasonably stiff already. Flex is going to happen up in the nose and between that area and the rear spring attachment points. So I call "minimal" on any chassis improvement. It also doesn't qualify as any kind of drive shaft retainer as defined by NHRA/IHRA. There are braces for Mustangs that tie the front and rear sheet metal frame points together with some cross bracing, those at least do something. Subframe connectors on older Mustangs are almost a requirement as those car twist like soggy bread.

boslab
07-02-2010, 12:32 PM
Dont know a lot about the stiffening effect of the sub frame, have seen a tie rod assembly that goes between Mcpherson strut heads so i suppose its that kind of tie anyway
a tripple hollow is an extrusion term to signify any hollow section with two internal webs, it is extruded through a type of die called a port hole die, normall die size 230-250mm diameter, usual configeration 2 cavaties with a matching bolster, normal press size 1600-1800 tons but a 2400 could push 3 or 4 cavaties reasonably well, typical uk alloys HE9/HE30, then water bath to get to TF temper, age harden 7 hours at 175, air cool, youd never think i left!
how useful the thing is on a floorpan [usually made of stronger steel than doorskin! i would not like to say, if it was steel of significant section maybee but i'd guess not in ali
mark

ADGO_Racing
07-02-2010, 12:36 PM
I'm sorry this doesn't qualify as a scam. It is a real piece, made by a real factory, sold by a real company.

I would like to hear comments from a real chassis design engineer.

I am sure nobody here really believes this to be a "Scam". There has been a good bit of conversation around the item. Most (including myself) don't believe it will have any significant effect on stiffness. "Bolt on stiffness" is in most cases, the same thing as miracle cure additives that you pour into your gas tank or crankcase.

Stops leaking valves, repairs cylinder walls, stops knocking rod bearings, improves gas mileage, STIFFENS YOUR CHASSIS!

Thruthefence
07-02-2010, 01:09 PM
Post it here:

http://www.eng-tips.com/threadminder.cfm?pid=87

you may have to sign up.

Evan
07-02-2010, 01:17 PM
Scam can be defined a number of ways. Taking your money and not delivering a product at all is without question a scam, as in fraud. There are less clear examples of fraud though, as in fraudulent advertising. If a claim is made for a product that isn't true that is also fraud and could easily be considered a scam. There are a couple that really bother me. One is the "Magnetic water softener magnets" and the other is the "Electronic rust protection". In my book both of those are scams since there is no supporting real evidence that they work and there is no explanation for the actual mechanism that is supported by the laws of physics.

In this case I don't know what the manufacturers claims are and I don't have actual numbers to put on the effectiveness of the brace so I can't call it a scam without test results and a look at the advertising. My comments are based on 40 years of metal working experience including experience both with racing cars and aircraft, both of which use aluminum construction. It is aluminum that I know the most about. In this case using aluminum to provide stiffness is a sad joke. Steel is three times stiffer than aluminum on a pound for pound basis. That means you could build the brace from steel and have at least 1.5 times the stiffness for the same strength and weight.

If you really wanted to stiffen that underbody with a brace like that it should at least be fully triangulated to the attach points. Never should a member end in the middle of another member, that weakens the structure. All members should meet at common tie points where the effects of welding have minimum negative effect.

That brace is strictly for appearance and bragging rights. If that is all you really want when you put down your money then it isn't a scam. I like the colour.

danlb
07-02-2010, 01:59 PM
And why in the heck would you want a "Chassis stiffener" hanging under a Toyota Prius??? Aren't those things in the "zero-to-60-in-one-afternoon" class?

That was hurtful. :( Off the line, a Prius will outrun most stock sedans and pickups. Works great when you need to change lanes. Within a hundred feet or so I'm at the 35 MPH speed limit and in the lane I need to be in.

But you don't need a 10 second quarter mile to find yourself pulling a couple Gs going into a corner. You can do that at relatively low speeds.

But to be honest, MY Prius (a 2002) was not designed for handling. So I drive it like any other non-performance car and don't even think about pushing the envelope.

Dan

Forestgnome
07-02-2010, 05:20 PM
I don't think it would add much stiffness. It looks like it is patterned after the shock tower braces, but the displacement in shock towers is much different than under the chassis. Plus it doesn't look like it even connects the subframes. It looks like it's only attached to one subframe.

dvbydt
07-02-2010, 05:55 PM
Car chassis stiffness is measured by locking down the front or rear suspension pick up points and appling a torque to the other suspension pick up points. The deflection is measured with a DTI and a known load. from this a simple calculation gives the twist measured in Nm/deg or ft.lbs/deg.

To make any sense of the chassis stiffeners, the manufacturer should publish before and after values, before making any claims.

IanR

EddyCurr
07-02-2010, 06:24 PM
I have no idea what "triple internal hallow wall" means,It may be a reference to a tube manufacturing process known as Butting.

Cyclists weigh the merits of bicycle frames on whether the tubing the frames
are constructed from is single, double, triple or even quadruple butted.
The term refers to differences in wall thickness at the ends of the tube
sections, relative to wall thickness in the center.

Reynolds has a page that give a brief overview here (http://reynoldstechnology.biz/our_materials_butted_tubing.php)

Dahon has a few remarks here (http://www.dahon.com/technology/frame-materials)A triple hollow is an extrusion term to signify any hollow section with two
internal webs, it is extruded through a type of die called a port hole die,
normal die size 230-250mm diameter, usual configeration 2 cavities with
a matching bolster, normal press size 1600-1800 tons but a 2400 could
push 3 or 4 cavaties reasonably well, typical uk alloys HE9/HE30, then
water bath to get to TF temper, age harden 7 hours at 175, air cool.
You'd never think I left!Thanks for the informative post.

It didn't occur to me that the description might refer to internal webs.

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