Proper intallation and function of strut tower bars [Merged 1-7]

[jtmcinder]

Earlier threads have said the "correct" way to install them is with the center of the car jacked up so they go in under compression.

What? You are supposed to install upper bars with the car on the ground because you want them to be under tension (if possible). The purpose of upper bars is to keep the upper half of the outside-wheel's suspension from pulling outwards in a corner, so the more preload tension the better.

- Jtoby

 

[DSMunknown]

What? You are supposed to install upper bars with the car on the ground because you want them to be under tension (if possible). The purpose of upper bars is to keep the upper half of the outside-wheel's suspension from pulling outwards in a corner, so the more preload tension the better.

- Jtoby

So what you're saying is, find four of your fattest friends and stuff them inside the car, and precede with the install? I am, of course, assuming they would have to fit...

 

[jtmcinder]

That, or have half of your strongest friends push in on the right fender while the other half push in on the left.

Not that more than one tenth of the people reading this have the grip necessary to make an upper STB even vaguely useful.

- Jtoby

 

[Defiant]

What? You are supposed to install upper bars with the car on the ground because you want them to be under tension (if possible).

That's what I'd always thought, until this:
http://www.dsmtuners.com/forums/showthread.php?t=175962
But I'm not in that 10%, either.

 

[jtmcinder]

I was recently reminded of this thread by Defiant....

In reality stiffness is difficult to acheive. Between the lower control arms 30,000-50,000 N/mm is what you want. And this is VERY difficult to achieve with bolted members. A 1" tube, bent to get around exaust with squished ends bolted in single shear at each lower control arm will be lucky to provide 5,000 N/mm.

If you applied 12.5 tons of compression between my lower front pick-up points, I have a funny feeling it would not crush one inch and then bounce back, so thinking about lower front STBs as springs seems rather weird. But even if we do approach it as you have suggested, my guess is that the most force carried by a lower front control arm is about a ton, so, if you are correct, my outside front might be moving inwards by only a little more than 1/16", so I'm not particularly interested in upgrading to a 30-50k N/mm bar.

- Jtoby

 

[daren_p]

What about the rear? When I installed mine I read to install them with the car on the ground, tension the front to pull inwards & tension the back to push out. Not sure the reasoning, maybe because the rear has a more agressive camber curve & this is to help compensate?

 

[jtmcinder]

The bump-camber curve is (mostly) set by the relative lengths of the upper and lower control arms. Pushing out via STBs is the same as putting spacers between the body and the upper inboard pivots: it deletes static camber and doesn't change the curve.

- Jtoby

ps. the bump-camber curve in the rear is only a little steeper than that in the front

 

[daren_p]

The bump-camber curve is (mostly) set by the relative lengths of the upper and lower control arms. Pushing out via STBs is the same as putting spacers between the body and the upper inboard pivots: it deletes static camber and doesn't change the curve.

- Jtoby

ps. the bump-camber curve in the rear is only a little steeper than that in the front

That makes sense, so what do yu recommend for the rear, or does it make much difference?

 

[jtmcinder]

Anything other than those bars with zig-zag backets, such as Pilot Motorsports. If only 10% of us need front bars, maybe 5% need them in the rear.

- Jtoby

 

[daren_p]

Anything other than those bars with zig-zag backets, such as Pilot Motorsports. If only 10% of us need front bars, maybe 5% need them in the rear.

- Jtoby

No, I mean how do you recommend setting the rear? I already have the crappy generic adjustable front & rears SB's that don't do anything, except look pretty I origionally had the nice DC carbon steel one piece bar on the front (that might actually do something) but had fitment issues with it hitting on the hood. This was when they first came out, I would imagine they have fixed that by now.

 

[jtmcinder]

Tension. As I wrote in that other thread, with regard to handling, they are designed to hold the upper ends of the suspension in, so a head start in this regard is better.

- Jtoby

 

[1LE]

Took about 5 minutes for the front. Most of that time figuring out which way it went I don't have it anymore, didn't think having it rub on my positive battery terminal was safe. Not sure what brand it was, but it was one of those jointed ones that I hate. Came with the car, so I can't complain though.

Rear one took about 30 minutes despite the fact that my car is gutted. It was the RRE bar, and the welded on nut on the end was turned so that it interfered with sheet metal in the area. Had to take a hammer to the car to dent it in some so that the bar would fit!

 

[bjones18]

I was recently reminded of this thread by Defiant....


If you applied 12.5 tons of compression between my lower front pick-up points, I have a funny feeling it would not crush one inch and then bounce back, so thinking about lower front STBs as springs seems rather weird. But even if we do approach it as you have suggested, my guess is that the most force carried by a lower front control arm is about a ton, so, if you are correct, my outside front might be moving inwards by only a little more than 1/16", so I'm not particularly interested in upgrading to a 30-50k N/mm bar.

- Jtoby

Everything in your chassis is a spring. Some stiff, some not so stiff. All of these springs are in series or parallel. A good design has the structure 5x stiffer than the rubber bushing. Looking at our LCA bushings, I would estimate them to be about 7-8000 N/mm radially. Anyone can slap a car together and it will go down the road; have you ever seen a junk-yard monstrosity? they work and they go down the road. A sixties vintage muscle car goes down the road. The difference comes in when you want to maximize lateral capacity, and be able to sense what is happening at the contact patch through the steering wheel. Also, if your structure is 5000 N/mm and your bushing is 8000 N/mm... you cannot tune your suspension with bushings since the softest spring in series is structure.

Your tie rod and LBJs (steering axis) are about 8 inches apart. 1/16" of displacement at your LBJ is 0.45 degrees of toe. (atan (1/16 / 8 )). At a 17:1 steering gear ratio that is about 8° at the wheel. When your structure is loading & unloading, creating "unaccounted for steering & camber input" it is like driving with knitted mittens and a nice fuzzy steering wheel cover.

 

[T is for TURBO]

Everything in your chassis is a spring. Some stiff, some not so stiff. All of these springs are in series or parallel. A good design has the structure 5x stiffer than the rubber bushing. Looking at our LCA bushings, I would estimate them to be about 7-8000 N/mm radially. Anyone can slap a car together and it will go down the road; have you ever seen a junk-yard monstrosity? they work and they go down the road. A sixties vintage muscle car goes down the road. The difference comes in when you want to maximize lateral capacity, and be able to sense what is happening at the contact patch through the steering wheel. Also, if your structure is 5000 N/mm and your bushing is 8000 N/mm... you cannot tune your suspension with bushings since the softest spring in series is structure.

Your tie rod and LBJs (steering axis) are about 8 inches apart. 1/16" of displacement at your LBJ is 0.45 degrees of toe. (atan (1/16 / 8 )). At a 17:1 steering gear ratio that is about 8° at the wheel. When your structure is loading & unloading, creating "unaccounted for steering & camber input" it is like driving with knitted mittens and a nice fuzzy steering wheel cover.

Somebody enjoyed their statics class

 

[bjones18]

Somebody enjoyed their statics class

Statics was fun (1985).

 

[slipstream808]

I got it in in under 2 minutes. Easiest thing EVER... no joke.

But the RRE one was bar FAR worth it. Car responds a lot better, feels tighter, and takes tight and/or fast turns without sqealing tires now. SOOOO worth it.

 

[nightspeed87]

I only have one in the front and was soon planning on getting on in the rear just to have it.

Now might I add, the strut bars dont seem as they do much for the awd guys,
but fwd guys will experience the improvement the bars make. I noticed the difference
soon as I took a hard turn with the front sb.

 

[1LE]

Now might I add, the strut bars dont seem as they do much for the awd guys,

My car is AWD and also has a welded in cage. Couldn't tell a bit of difference at all when I removed the front STB. Didn't seem to make any difference at all when the rear STB was added either (I only added the rear bar so I'd have something to tie my rally gear to)

 

[nightspeed87]

yea so to sum it all up, strut bars are only worth while to be effective for the 2wheel drive guys. Thats probably why there more common in the honda world. I personally like them on my gst, but realize if I had awd I probably wouldnt bother unless Im just going for the look of having them.

 

[nightspeed87]

yea i didnt raise my car up when I installed the front bar.
When you say raising , as in getting both tires off the ground right? ( just to clarify how much is actually being raised.)
Does raising the car also go for installation of the rear bar as well?

 

[DSMunknown]

http://www.dsmtuners.com/forums/showthread.php?t=246120

 

[Deadly BlaZe]

I've read several threads about people arguing whether to install the front strut bar with the car raised or on the ground. Is there anyone that has seen benefits of one over the other?

 

[just2asian]

you don't need to raise the car, just undo the bolts on the sturt towers and slap the strut bar on. Just make sure you adjust the tension so that you get maximum efficiency because nothing is worst than a loose strut bar

 

[jtmcinder]

If you are asking for back-to-back lateral g values with the bar installed correctly and incorrectly, then you're in for a long wait.

If you're asking for values from someone's butt-dyno, then you're in for a lot nonsense based more on cognitive dissonance than anything objective.

If you're asking if the logic behind these bars has changed, such that knowing what they are designed to do no longer says install them with the car on the ground, then the answer is "no, the logic is still what it was when this question was asked last time."

- J "needs more coffee" toby

 

[spinninfwdlaser]

I did mine on the ground, and torqued the bolts. I honestly noticed a difference as well.