Are you supposed to have your car suspended when putting the FSTB on? someone told me that you can "LOAD" the FSTB if you put it on with the suspension hangin in the air. So that way it more pressure on the FSTB so it hold more rigidly. Any truth to it?

 

who told you that and what are his credetials?

 

Name:Michael Vietz, avid Autocrosser and course racing guy.
The concept sounds viable, I didn't know if anyone had any insight to this.

 

uh, the nuts that attach the FSTB hold the strut/suspension on, if you losen that while suspended in the air you suspension would become very lose, possibly come out. Plus your never gonna get the nuts tight enough up top while the supension is in the air, as soon as you bring the car back down those nuts are gonna be lose again thus losing the point of trying to load it int he first place

if im worng please correct me

 

I thought it was best to do this install, on a flat non elevated surface?

 

i guess he means u put it on when the car is on the floor, but adjust it with the car in the air. with the car off the floor u could push the struts futher apart. sounds logical

 

When the car is raised there's less inward force on the strut towers. Then, when the car is lowered back down the strut towers want to flex back inward, creating more force/rigidy since the FSTB is forcing them outward.

I personally dont think it makes much difference at all, but it is relatively common.

 

Also, I've only heard of this being done on lowered cars. Apparently, if your car is lowered you need to "jack it up some to bring some of the chassis flex back out in order to make it fit properly."

My car was lowered when I put mine on. I didnt bother, just undid the bolts and slapped her on.

 

so wait, i thought the FSTB was to keep the front end from not flexing outward(meaning the FSTB keeps the towers closer, rather than keeping the towers further aprart), loading the front would just render the FSTB usless no? i dont know maybe it works bith ways. Either case i would think to see very minimal gain in handleing

 

so what exactly is the best way to do this?

 

No you have it backwards.

Under hard turning and what-not, the top of the strut towers want to lean inward (toward eachother). The purpose of the FSTB is to keep the strut towers from doing so, and thus tightening everything up, crisper response, better turning/handling integrity, etc.

Either way it's not going to make a big enough difference to warrant going through the hassle of "loading". However, "loading" is perfectly fine and the theory behind it totally checks out. It's just not worth the hassle.

 

Thats what i thought at first, but then i read that it was backwards(opposite of what your saying) somewhere? At any case we both agree its not worth doing.

 

Actually you're mistaken here. Under hard cornering the strut towers are usually forced outwards. This is due to the strong lateral forces being applied to the tires. These lateral forces try to push the bottom of the wheel under the car. This in turn causes the wheel to want to rotate about the lower arms of the suspension. The only thing stopping it from doing this is the upper strut which then pulls on the frame. See here for a more indepth look (with pictures):

http://e30m3performance.com/myths/St...bar_theory.htm

That said, it should also be noted that under straight line driving bumps in the road can cause inward movement of the strut towers (i.e. compression of the strut bar). All told the FSTB will see both tension and compression conditions.

Thus the best way to install the bar would be under neutral conditions, i.e. the car sitting on flat level ground.

Myrv

 

Very well said, install it on flat groung... end of questions I hope...

 

um, doesn't that link show the force pointing inward towards the engine bay?

 

Yes, the loads applied to the chassis due to the suspension are inwards. The reaction force of the FSTB's brackets is outward. Either way, it's better to torque the FSTB with the car on level ground. The FSTB is supposed to work on the car in it's sprung state. This is why it is better to have it torqued down on level ground.

 

Somebody knows what there talking about!!!

It's true and has been proven that the FSTB sees more outward pulling forces then it does inward. There is a web site someplace where some kind of force gauge was placed in series with the FSTB to see which direction it encounters force.

The results were very much the opposite of what you think.
It wasn't inward force it encounters, however it's pull from the oposite wheel it sees most.

Therefore, preloading your FSTB is only applying more stress on the chassie of your car. It should be installed in the neutral position and secured in place to give your cars chassie a more solid feel.

 

Sorta, but it's not the force the body is experiencing.

The arrow at the top (F3) is the force that is required to hold the suspension system in place. i.e. it is the force that is keeping the strut from swinging out. What's supplying this force? The body is, but as our friend Newton said (paraphrased), for every action there is an opposite and equal reaction, and so the strut is acting with an equal force against the body. It's this force that is forcing the strut towers apart.

Unfortunately all this isn't immediately obvious from looking at the figures shown in the link.

 

so now we conclude that the strut bar does nothing at all.. it is just in our heads..

 

I think that loading is a practical thing to do if you want to take the time to do it. It applies positive pressure on the strut towers when the car is back on the ground, taking the "play" out of the front tower space. The next question is how do you know that force is evenly distributed?

 

i knew i wasnt crazy

 

This would be generally backwards from what the bar is supposed to do. The bar is supposed to hold the chassis square and more rigid than stock, improving chassis behavior by eliminating unwanted deflection. If you elevate the car you can't be sure the chassis is still square and likely will tie the strut towers together with the chassis distorted. Secondarily, why on earth would you want the strut towers farther apart, giving more positive camber when you really want it more negative???

 

Thats why I was asking, thanks for your input.