Strut bar question

[ti1301]

Got in to an argument with a friend today.
He said my DC sports strut bar sucks cause it bend when he pushes down on it. He says a STIFF bar that won't bend is better.
I say BS. He exerted a direct downard force ont he middle of the bar to make it bend because it is made of light weight aircraft grade alum.
I told them that the bar is subject to horizintal forces when teh chassis twists so just cause it bends when he pushes down on it, it doesn't matter.
In my opionion all decently made bars will perform the same. I swear if you replaced my DC with an el cheapo stock bar I would never know till I looked.

So you folks think my friend is right?

[tFUnK]

ive heard nothing but bad things about the dc bars... there's some logic in ur explanation but have you tried to bend it the other way? well in theory if strut bar bends then it isnt doing it's job...

[Daniel]

A strut tower bar SHOULD NOT flex because what is its intention? To keep the chassis from flexing. If it's bending in any direction, the chassis is flexing, so it's not doing its job correctly.

Let's use an example ... a box without a top. Get a piece of thick paper, and cut it into a long, rectangular shape just long enough to reach one side of the box to the other. Now, twist the box in a lateral motion like what a car would undergo. What happens to the piece of paper? It bends down and up, depending on the box's motion, and look at the box: it's flexing! Replace that piece of paper with something slightly sturdier like a piece of thick cardboard or whatever. Try to twist the box now. See a difference? The piece of cardboard isn't moving up or down, and the box has less flexibility than before.

This same principle applies to a car's chassis and strut tower bar. It doesn't matter if the car only experiences horizontal forces; a strut tower bar is supposed to keep its shape to prevent the chassis from moving because as shown in the box example, if the chassis is allowed to flex, the strut tower bar that is installed and not working properly (read: DC Sports strut tower bar) will move up and down because both of its ends are bolted to the car and have nowhere to go. Thus, the horizontal forces are translated into vertical motions applied to the strut tower bar. So if the strut tower bar can flex, the chassis can flex, which is what's not supposed to happen.

And actually, now that I think about it, the chassis experiences vertical motions, too. Have you ever tried to enter a store's driveway at an angle where the driveway is an aggressively angled slope that abruptly flattens at the top? I have, and let me tell you, my Civic's chassis isn't moving horizontally; it's moving vertically. And what's worse, with all the bars I've installed (front strut tower bar, front tie bar, and rear anti-sway bar, which also acts as a rear tie bar), the chassis can't flex enough to keep all four wheels on the ground, so the front passenger rim will actually lift off the ground and land with a loud THUD. :(

I can see where you're coming from, though. Intuitively, your belief makes sense, but things happen in mysterious ways.

[ti1301]

ahh I see. Thank you for your response. It was helpful.
But don't you think that the bar is made strong enough to withstand enough torsional forces and the bending is an acceptable occurance because it has been designed to withstand the forces acted upon it by the and the bending only occurs when the net force is greater than actual?
I'm just throwing that out. I don't think DC would make such a crappy bar. Think about it according to torque laws, the bar would not bend as much if my friend had pushed down at it from the side as opposed to the middle ot the bar.

The flexing would suggest that the stock el cheapo bar is superior to the DC then. I know DC had light weight in mind when they made theirs cause every racer wants to reduce weight.
None the less, in actual use, I don't think you could tell the diff between the "flexing" DC and a El cheapo bar.

All decently made bars must have been desgined with a torgue range to withstand the torsional forces acted upon it in a car so the flexing wouldn't matter. If it flexes due to extreme forces (forces which will not be acted upon it in driving use) then that is acceptable. Sure there will be some vertical forces, but sometimes you need the flex like you mentioned. That's my take.

[tFUnK]

im sure cosmetics was part of DC's plan on their strut bars... the cOoL holes on the bar has gotta make the bar less stiff. the oem strut bars (honda/acura at least) are pretty well designed... simple and sturdy, just like how it should be.

[tFUnK]

another question:

is it ideal to tighten and bolt on the strut tower bars when the car is jacked up and suspended in the air so that the wheels hang freely?

[XTC Dynamic Supra]

yeah on it's wheels...if you do it while it's in the air you will be basically preloading the frame. Hence causing the struts to sit and the wrong position. Tighten them while it's down. Also a strut bar shouldn't bend at all. The el cheapo apc/pepboys strut bars are $30 for a reason. Personally i love my Cusco bars. They don't flex for shit.

[POSCar]

The 4-point Neuspeed bars are the best bang for the buck.