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ok, so not arguing with him, but i asked Wenuden about what he meant by preloading his strut bar and he responded with this...

Wenuden wrote:I put the front end on jackstands after i removed the 2 nuts on the strut mounts, installed the bar and nuts, then put the car back on the ground. That's how i installed the rear strut bar on my sxt, and when i took it off, with the car on the ground, when i took the second nut off the passenger side, the bar flexed up and the nut went flying across the trunk. i was intrigued, so i put the bar back in on the ground, and drove it for a few weeks. when i took the bar off that time, the nuts just came off. i figure doing it that way doesn't hurt the car, and it must stiffin it a bit more. i didn't have any problems with the rear end driving like that for about 3k miles.

i'm just curious if anybody else had any thoughts. again this isn't cause i don't believe what he said. it's cause i'm just curious and didn't really care to be an ass and thread jack his picture post

Yes that is what you are suppose to do. The idea is that the weight of the car itself flexes the strut towers inward, so when you take the weight off the car, install the strut bar, there is no way for the strut tower to flex as much. I don't think anyone would be able to tell the difference though.

This has been beaten to death, and this will be the first time I say this, but please search.

There are 2 camps on this discussion, one that it matters, one that it doesn't.

When installing my strut tower bars on my current '02, I could not do it with the car on the ground. I had to jack the car up and place one jack stand in the middle of the rear of the car and take all the weight off the jack, then the bolts lined up.

I tried to unbolt the bar on the ground yesterday and remove the bar and I couldn't. No matter how hard I pulled, it would not come off.

Food for thought.

sorry bout not searching. it was midnight and i was about to pass out. i wasn't thinking. but thanks for the input. at least you didn't just leave it at tellin me to search.

Canada's good people like that.

You're not to bad yourself Frank. (In a totally non-gay way )

http://forum.2gn.org/viewtopic.php?t=89 ... t=bar+load

An example of one discussion.

i actually found that one when i searched earlier

Preloading the bars isn't going to do anything. It's still going to seek the same status-quo of force no matter how you put it on... unless the laws of physics seize to exist on your strut towers.

The onlything that will change something is chaning the length of the bar. And since not all bars or cars are created equal, you may have to raise the car to get the bar to fit on... but it will not change anything on how it functions.

Installing the tower bar with the suspension in a neutral state seems like a good idea, but the difference is surely very minimal in most cases. Our cars have a lot of stuff going on in the front, which leads one to believe that the chassis flex is probably much more pronounced in the rear, where there is a lot of empty space and not much support. Engine and trans mounts in the front act as chassis stabilizers in a way, and upgraded inserts or mounts make even more difference. The rear of a front heavy sedan is the place to make the chassis mods in my opinion. A nice x brace would do wonders. Hmmm

When the bar is installed with the car on the ground and suspension loaded the strut towers are being pushed in. When in the air there is no stress. So when installed on the ground you're keeping the body in a stressed state, when installed with the car in the air, you're helping it hold its shape, which is what chassis braces are supposed to do.


On ground /```\
In air |```|

i'm going to have to remove my front strut bar in the next couple of weeks to install an intake. i'll remove it with the car on the ground and let you all know if the nuts holding it on go flying across my drive-way and get lost in the yard (indicating that there is, indeed, pressure placed on the bar by installing it with the wheels off the ground, like there was on the rear of my sxt).

It still doesn't matter how you put it on, espcially if the bar is not adjustable.

^^^ your posts would be a bit better if they contained any kind of information whatsoever. the first one mentions physics, but you don't elaborate. then this one is just a statement that i consider to be your opinion stated as fact, since there's nothing to back it up.

If you (re?)read the quoted text in Hudson's first post, you'll see that i had 2 different results from 2 different installs of my original rear strut bar.

the bar used was a DC Sports carbon steel bar, not a cheapie aluminum bar.

w/ the bar installed with the tires off the ground, the bar flexed when i removed the 2nd nut from the first side i removed. the car was on the ground when i removed it, which indicates that there was (obviously) stress on the bar.

w/ the bar installed w/ the car on the ground, and removed with the car on the ground, the bar did not flex, indicating there was no stress on the bar.

please explain how this is the same act of physics (i'm sure my question is posed improperly, but you should understand what i mean).

other than driving about 2400 miles on the first install and only about 800 on the second install, there were no differences in the car, so i consider this a fairly well controlled experiment. while there was no HUGE noticable difference in cornering, i am not an inertia(?) measuring device (potentiometer?? i don't know lol) and can not say for certain that there was no difference in cornering g's.


i'm not trying to be a dick (well, maybe just a little), i'm really just curios as to why you feel you're right.

Disclaimer: i'm NOT saying the way i do it is the way it should be done, it just makes me feel like i've done as much as i can to stiffen up the chassis of the car with what i have (plus it doesn't take very long). if you do yours this way, and lose an eye to a nut or get smacked in the forehead with a bar when trying to remove it, it's your fault not mine... lol.



Edit: this post is what results when i toke up lol. i forget that i'm more of a doer than a thinker, and make attempts at intellectualism.

ok, so putting it on in the air... does the one leftover nut hold the strut up adiquitly?

it worked fine for me. i had the car up on jackstands with both tires supported with hydraulic floor jacks contacting the tires with just enough pressure for the whole assembly to not be being supported by one thin bolt and nut, but not enough to compress the strut any, or change the distance of the bottom edge of the tire to the ground. lol does that make since to you, cause it does to me... kinda....

got it. i only got one jack, besides the BS that comes with the car, so it might take a tad bit longer for me

I was able to put my Vibrant strut bars on while on the ground. I felt the difference in feel was not as much as the sway bars, so I took it off. I had bought the bars used, and for the rear I could see where the old owner had the nuts put. Interestingly enough, I couldn't get the bar to fit on the rear of my R/T unless I completely backed the adjustment nut/bolt out. Well not completely, but almost there. This would seem to, in my opinion, contradict the theory that the suspension collapses in on itself once on the ground. Of course, it might be because I have an R/T and the other guy had a base car. Or it just could be loose tolerances.

In any event, theoretically, raising the car would "unload" the front of the car, but I think this unload would only be near perfect if the whole car was up on jackstands. If you only lift up the front and vice versa, a little bit of torsion caused by the opposite end might splay the other end out further than you think. On the other hand, even when you load the car on rigid jack points, the suspension is never 100% rigid and the car will flex a little bit in some direction, and all you are doing is changing the load points from the wheels/strut tower, to a theoretically rigid point on the body.

In my opinion, however, if the collapsing done by the shock towers is minimized, then only the return point or the 0 point at which your suspension is set will be affected. Say the shock towers deflect on stock setting 15 degrees at rest, and say it goes negative 5 degrees from vertical once 100% up in the air. This is an extreme example, but if the shock tower brace (and the car) is any damn good, any kind of load should not go too far beyond the set 0 point. Without a brace, say the car experiences positive 30 degrees of flex (from 0) under operating conditions. Say you now install a brace that only allows 1-4 degrees of flex under operating conditions (at rest, up and down, aggressive driving, etc). If installed at -5 degrees (or 100% up in the air), the strut towers would theoretically flex only between -4 and -1 degrees. If installed on the ground, it would flex between 16 and 19 degrees. Both are improvements, but the real issue is the minimization of flex, not so much the set zero point.

Unfortunately for most cars, a major weak point is using the strut bolts as mounting points instead of the strut towers themselves. A little bit of shearing force experienced by the strut bolts might allow the thing to shift ever so slightly, thus possibly minimizing the effect of the brace. I noticed on my friends Mustang factory strut bar, all 4 bolt points mount onto the shock tower, and a rear one must be welded in.

Conclusion? Well it depends on if you want that "load" in there. Some might try to purposely pre-load the bar to get a near vertical setting while others might want it to collapse in a little. Honestly, I want it to be a little trapezoidal, because you learn in structure design that square does not always mean strongest.

That's just my opinion on the matter, just thought up right now. I am by no means an expert of any sort, I just applied a little thinking from my strength of materials class. My math and logic might be a little off, feel free to correct me if I'm wrong. By the way, I took the vibrant ones off, I'm selling them if anybody wants it.

IMO, setting up the suspension while it is in an "unloaded" state would take away from the whole idea behind the modification in the first place. The car is driven while it is under load. The weight of the chassis is meant to sit on the suspension, and the squat, dive, and cornering forces act upon the car while it is in this loaded state, not while its wheels are off the ground. Tuning the vehicles suspension while the weight of the vehicles is off the ground just doesnt make sense.

Think of the car sitting on all four wheels as being the base of the suspension's travel (The chassis is part of the suspension in this case). Changing the base situation while the vehicle is in an abnormal state (suspension fully unloaded) isnt a good way to realistically modify the stability of the chassis. It should be done from a starting point that is both neutral and applicable to the desired result. You dont need to minimize chassis flex when the car is off the ground, so dont set the suspension up to do so.

Anyone get my point?

i hear you. it seems that EVERYBODY has something to say on this. i'm taking it ALL into consideration

OB wrote:IMO, setting up the suspension while it is in an "unloaded" state would take away from the whole idea behind the modification in the first place. The car is driven while it is under load. The weight of the chassis is meant to sit on the suspension, and the squat, dive, and cornering forces act upon the car while it is in this loaded state, not while its wheels are off the ground. Tuning the vehicles suspension while the weight of the vehicles is off the ground just doesnt make sense.

Think of the car sitting on all four wheels as being the base of the suspension's travel (The chassis is part of the suspension in this case). Changing the base situation while the vehicle is in an abnormal state (suspension fully unloaded) isnt a good way to realistically modify the stability of the chassis. It should be done from a starting point that is both neutral and applicable to the desired result. You dont need to minimize chassis flex when the car is off the ground, so dont set the suspension up to do so.

Anyone get my point?

I understand where you're coming from but thats not the point of chassis stiffeners like strut bars. The whole idea behind them is to keep the chassis from moving from where it was intended to be while its under load, which is vertical or the 0 point that 01NeonR/T mentioned. Not where it is going to move to.

There may be some validity to the arguments, but will you notice the difference driving? Probably not. Just do what you have to do in order to make the install easy, and move on to other things that will make better use of your intellectual resources. Like going to work to make more money for more neat parts.

I wonder if there would be any difference is say, wheel alignment if the car was preloaded with a strut bar and not preloaded... ?

I believe in raising the car up and installing it, so honestly, if you disagree good for you for practicing your 1st amendment right (free speech and right to disagree )

Allright. Just a thought. If you jack the car up on one side in the rear, then the car will be flexed like this U (obviously not as much as that but it's eliminates any confusion as to what direction it's happening in)
And then if you put the strut bar on and lower it to the ground, the bar will be stretched, which will not make the car stiffer but actually less stiff because it will gladly "give" to get back to that original state.
If you jack the car up on both sides in the rear, it should flex slightly like this ^ but maybe not enough to make a difference. However, if you jack it up from a central location in the rear, it should produce more flex like ^ which means that when you put the bar on and lower it to the ground it would be genuinely preloaded. I think perhaps alot of the confusion surrounding this topic stems from the fact that jacking the car up in different ways and from different points changes the way it flexes.

in the center is the ONLY place i've ever jacked my car up at in the rear.

So what u said is that if Im going to put a front bar I should raise the rear of my car in the middle and if Im going to put the rear bar I should raise the front of my car in the middle on the front???

Is a strut bar really all that important on a unibody car like ours?! Is the torsion we are putting on our cars that much? The body of our cars is like one giant bar itself...

Yes, when driving hard the whole body twists since there is no "frame" only the body. The roll cages in race cars aren't only for safety, it stiffens up the chassis to allow the suspension to work instead of the body, allows for a more predictable and stable car.