Talk:Strut bar
Hard Data on Strut Bars?
You have a well-written, suscinct page on this topic.
However, your link on "strut bar theory" is to a discussion group where one person only advances a THEORY on whether these are actally of any worth.
His theory only re-states the obvious, that if you tie together the strut towers, you arguably create a stiffer structure. The rest of that link is litle more than speculation as to what forces are involved during cornering. The real crux of the theory - how much a given strut tower will deflect under such conditions AND whether such deflection will result in sufficient suspension geometry change to alter handling, are not even addressed.
The only "evidence" presented is the comment "And I have heard of incidents where the strut tower bar was instrumented with strain gauges as the car was driven around. These tests show the strut tower bar is under compression as well as tension, depending on what the car is doing."
Again, even if such test data exists, it doesn't answer the fundamental questions as to whether this affect suspension geometry and more importantly, handling.
I am not aware of any hard test data (with real world measured numbers, instead of theoretical values) showing that these devices improve handling, particularly for street cars.
If you read the parts catalogs, you will note two things:
1. Like most automotive accessories, how the device LOOKS is heavily hyped. Most are stainless steel or polished chrome or anodized aluminum. If this were truly a "performance" item, such "dress-up" would be superflous.
2. No hard data is presented on cornering ability, but the catalogs mention that it improves cornering "feel". IN fact, the catalogs go out of their way to avoid mentioning that it improves performance.
See:
http://www.bavauto.com/shop.asp
"This strut brace is manufactured by CNC machining of strong aluminum billets to ensure strong lateral rigidity and a special look to your engine compartment. End plates are also billet and are machined on high speed CNC machining centers for exactness and repeatability ensuring the BMW owner of the finest strut brace available anywhere"
http://www.bavauto.com/shop.asp
Improve your BMW's handling! Our stress bar locks the top of your 3 series' strut towers together to improve chassis stiffness and handling. The result is greater stability in hard cornering--a difference you can really feel, giving you greater confidence and control. Made of strong, lightweight aluminum, it's manufactured in Germany and available only from Bavarian Autosport.
"Seat of the Pants" data is really not very convincing.
It would seem to be a simple matter to instrument a vehicle and drive it in different conditions and measure the deflection of the strut towers (auto manufacturers do such testing all the time). Or, failing that, to compare track times or slalom course time with different drivers with and without the towers (in a blind test, not telling the drivers whether the bar is installed).
But I am not aware of any hard data on this. Like "wings" and "ground effects" some manufacturers are adding these strut towers to their "sport" versions in order to sell cars (along with fake hood scoops, and the fake front fender gills). But I don't see any science showing that these things actually work.
Frankly, I think they are about as effective as Deer Whistles.
If there is some hard test data, I would like to see it, before dropping $800 on a piece of metal.
Joe Patent (talk) 00:27, 8 December 2008 (UTC)
The link in the article is pretty much all plagiarized from Gustave Stroes article as well. Here is an article with hard data: http://www.evolutionzen.com/chassis-compliance.html 75.38.114.151 (talk) 02:04, 6 April 2009 (UTC)
That link is dead, is there another source for "hard data"?
Joe Patent (talk) 02:39, 17 February 2010 (UTC)
It's fun to see the Saab 96 mentioned (I own a 95) but I'm not sure the crossmember in the engine compartment of that car is a strut bar in the modern sense. As the article notes, the car uses double-wishbone suspension. I suspect the real reason for the "strut bar" is that the radiator core support on these cars is held on with screws and clips, and doesn't really provide any structural strength. The "strut bar" is in fact the only structural member tying the left and right sides of the front of the car together at the top. Without it the front of the car would be a rather weak U-shaped structure. By contrast, modern unibody cars usually weld the core support to the front subframe and wheel wells, making the whole front clip one structural assembly. 06:19, 19 August 2009 (UTC)