Cause it's better to make your own..I Made it a 3 point. I'll post new pics when it's powdercoated.

 

Very nice job. Bet it looks great after the powdercoating. What diameter tubing did you use and what are the clearances to the plenum and hood?

 

how is that a 3pt? i only see 2pts?

what DIA and thickness tubing u use? im gona be making my own as well, but i have to get mine to fit over the HSR. im gona be using 1.5" .095" thick tubing. and 1/8" plates for the strut mounts

 

Actually it became a 4 pt. I'll post the new pics soon.

 

what hood are you using? that wont clear a stock hood, well maybe if its a camaro

other than that, it looks good, very similar to one i made a while ago, i left it just like in your pic, 2 pts. I made a different 3pt one in using now.

 

It will clear , in fact it will clear a T/A hood too. That sits lower then my Edelbrock elite air cleaner.

 

hmmm, it looks close. I was just thinking about UMI's STB, the bar is made in a similar fashion, and its even notched to clear the plenum and the trans am/gta hood wont clear. Oh well, i'll take you word for it.

 

I assume by his name that he has a Camaro, so there shouldn't be any clearance problems.

 

I also had a Edelbrock carb on my T/A with adapter which raised it like 5/8's higher , then a air cleaner and it still didn't rub. What I did was took play doh and formed a few peices of it and set it on the air cleaner,Then closed the hood. I had about 1/8's to 1/4 clearance.

 

Here's the finished piece. It's 1" dia. 1/8th" thickness steel dom tubing. I hope it clears the hood but I haven't put it back on since the engine swap so I'm not certain. I get lot's of compliments about the motor so I've been in no hurry to put the hood back on.

There's 1/8th" clearance between bottom of the brace and the plenum so I think I'm ok. From the posts I read I should have room.

86 TA...If yours is the square tube 2 pt that was posted here that's the one I copied... just used round tube instead and made it a 4 pt....obviously. Thanks for the inspiration.

 

i like the 4 point idea but i dont like the plates u used to mount the brace itself if i get around to my car i will post a pic of the one i made

 

Can't wait to see it.

 

nah. mines the 3pt round tubular piece that i modified. i just got it back form the powdercoater today actually, after some changes. Looks so much better than it did painted.

 

Pretty Nice. But i like my BMR better. even though its only a 3 point. But you did a fantastic job. Props to you!

 

Those 3rd and 4th points aren't going to add much overall chassis stiffness.

But they will at least stabilize the lateral bar against "falling over" in the fore/aft direction when that member gets loaded.

Near as I can tell, the ideal 4-point STB connects to the firewall at/near the A-pillars, with an "X" brace covering the middle of the rectangle formed . However, I won't say that doing this would be easy, or even realistic, in any given car.


Norm

 

i like that idea norm.... ive seen some pics of crazy stuff , one guy made a 12pt strut tower lol... it was nuts. but i agree that the 3pt and 4pt wont add overall rigidy to the front subframe etc unless connecting at the pillar points but will help the bar from falling forward or backward. the only issue i see of that is that getting to the engine will be difficult with it on. but it would look sick otherwise

 

On a Camaro, you'll be fine, as long as the 2 cowl bars don't hit the bottom of the hood. If it was on a Firebird, you'd have issues. Under a GTA hood, the hood wouldn't close.

 

Your brace looks good.

However Im alittle skeptical on really how stiff it is. Better than nothing though.

 

im sure the main section is plenty stiff, but the points going to the firewall are pretty much useless.

 

How do you figure the 3rd and 4th points to be useless I wonder???

 

Since you only attach the smaller tubes at one point on each end they are free to rotate in the plane of the bolt hole under load. Like said previously, you'd also want to connect them at the pillar points for increased rigidity.

 

Because nothing is feeding loads directly into them at the lateral strut tower tie bar. At best, there are some bending-related effects that are not very effective in adding either stiffness or strength.

They provide lateral stability to the tie bar and not much else.


Norm

 

Check the following link, post #24, where Dean discusses the STB:

https://www.thirdgen.org/forums/susp...install-2.html

JamesC

 

I am certain that Dean's 3-point STB has the diagonals attached at or near the ends of the lateral tie bar, at/near the strut tower connections, not near it middle of the lateral. That's a HUGE difference from the situation here, although it too requires some beam strength/stiffness in the firewall against fore/aft loads in order to be fully effective.

I figure after almost 40 years of getting paid to do structural analysis that I've got a pretty good idea how this fairly simple piece of structure behaves.



Norm

 

Hmmm. Well sounds reasonable enough but my car's front end is much stiffer now so I accomplished what I set out to do. Not to mention I think it looks pretty bitchen. Thanks for the info though.

 

you could have probably been fine with just a 2pt since thats all thats really needed unless the cars a autoXer etc... still looks good tho, nice job. the extra points make it look a bunch better but u might have some issues with the hood closing with the bolts on the top of the windshield brace. my aftermarket fiberglass ram air II hood rests right on that sill area

 

Hi Norm,
Blackbird wanted me to chime in here thinking we slightly disagreed on something- but after reading what you wrote on the a-pillar links 'with x brace connections" so to speak I fully agree with what you suggested but you also wisely stated it is typically impossible to do so on a third gen.
Blackbird was asking me why I would 3rd link it rather than 4 point it from the center of the STB towards the a-pillars? I explained to them on another post about how weight is transfered diagonally on corner entrance and exit, so in order to maintain chassis stiffness a diagonal brace off the towers towards the center windshield structure/firewall (since the windshield is chassis structure and a major portion of chassis design strength) that the chassis will not fold over onto the tower diagonally on corner entrance. It is the simplest method of STB design keeping the towers spread laterally as well as diagonally spread fore and aft using a simple triangulation support structure to a firm center firewall/windsheild point.

Dean

ps- on another note, I had a stock Edelbrock 3pt STB design that is flawed at the 2pt mounts on the strut towers. I did a simple field test of the flimsy brackets and realised they were flexing fore and aft. Once O box weld braced the tops of the Edelbrock brackets the car tightened up on corner entrace due to less chassis flex and I higher maintained x-weight. That alone told me the 3pt triangulation ot the firewall center of the windshield was truely effective in chassis stiffness.

 

CustomBlackbird, Here is a picture of my Camaro showing where and how it is braced. You can see how I added the yellow box plating. The blue lines is the basic structure of the car and you get the idea how the windshield boxes the apillars and why the center of the firewall is solid.

Even though my diagonal struts do not attach near the towers, they still do attach at enough of a diagonal to triangulate as well as the beam they tie into is retangular steel tubing that is supportive to distribute the load to the towers. and keeping the upper cockpit chassis weight from flexing towards the towers.

You need to think on terms of the roof flexing towards the towers rather than the towers flexing towards the roof when it comes to load and direction in vehicle dynamics under braking and cornering. Keeping the roof back keeps the rear of the car back and keeps the chassis stiff and the rear tires planted- think of it as cage structure.

 

Dean,

Please feel free to correct me and point me in the straight direction but.......

First off, im just talking about the 2 pts from strut tower to strut tower. A straight piece of steel would be the strongest. However this is next to impossible due to the engine. In this particular brace, the 2pt bar is completely curved. To me this looks far weaker then if made from 3 straight box sections.

If you were to take a piece of 1/4 rod and shaped it in a similar way, then if you were to push together at the ends, it would merely bow even further. However if you were to take straight sections you can carry the force better with out flexing.

Does this make sense? I just look at the 2pt piece as being weak in comparison since it is bowed. Looks to me like that just makes it easier for the brace to bend. Im sure its better than nothing, but just doesnt look as strong as a tubular sectioned piece.

Your opinions?

 

Thats looks great.

 

I 100% agree. However I am no expert on metal fabrication. Hopefully Norm can give us professional insight on metalology (I think thats the word I am looking for- the strength and integrity of metals).

I do know I picked the Edelbrock STB to work with solely because it was in fact 3 pcs of retangular tubing cut and welded rather than one piece of tubing arched.My mouth stands where my money was spent- (smiles)
Dean

 

More is better, right?

 

That looks like it would be a pain to get to anything in the engine compartment, lol.

BTW, I performed a simple stress analysis in Solidworks (b/c I'm bored) to compare the curved tubing to sectioned tubing. The results had the curved tubing being ~1.7 times better at resisting deflection when a load was applied.

EDIT: Here are the models that I used. Both are 1" dia x 1/8" thick tubing.

 

Assuming that the curved bar is made from the same tubing OD and wall thickness as the straight bar that you'd rather be making it from, yes. The straight bar will carry more load before it buckles and will be more rigid than the curved bar shown.

It's not as clear when you compare a curved bar to a bar that instead has miter joints between the ends to gain the same clearance (around the engine parts in this case). There are stress concentration effects at miter joints (more local flexing is going on), and with the mitered bar there can under certain load conditions be a longer length where the bar is subject to the largest bending moment (meaning that part of the mitered bar would then deflect slightly more). I wouldn't think it wise to call it either way here without either running some numbers (something I could do on the other computer) or doing some testing (something that Dean may be better set up to do).

Here's where the cross-sectional shape of the lateral tie as well as its cross-sectional area matter. The further away from the middle of the tube you can get the metal (and the more metal you put way out there, obviously), the more rigid the tube becomes. This applies whether the tube is straight or bent/curved, though it's probably more important in the curved case. A perfectly straight tube won't bend until it's about to buckle. A curved tube starts to bend as soon as you load it at all (although this is only a tiny amount at first).

The center section of the mitered bar starts out with some bending happening as soon as you load it at the tower attachment points, so you aren't exactly getting pure straight bar behavior any more.



Norm

 

Thanks, cale.

And 'stress analysis' is the term that Dean is looking for, so thanks again.


Norm

 

Please do not take any offense to this, but How much experience do you have in solid works and stress analysis?
Only reason I am asking is that I have used FEA in the past and I have seen how things can be off by simple mistakes in the loading and properties. Im not arguing with the results, Im just curious how close they might actually be. I am no expert, thats why I have seen so many things wrong, lol.

What kind of forces did you use?

 

3rdgenmaro, The other factor you asked about and both youy and cale might be disagreeing on is that he stated the models he used were both 1" round tube. You had asked for a comparison of the round tube and the 1.5" x 3/4"x 1/8"thick rectantular tubing on the edelbrock unit.

Rhe models are also not near exact to real world specs as the Edelbrock unit does not arch up as high since the tower ends start higher and project accoss at flater angles and much longer stright center section, wereas the arching tube units generally incrfease radius dramatically towards the towers bending the load at the extremities on at about 60* bends wile arching across the span mostly at about aprox 45* totaling aprox 165* bend from start to finish (since the tower mount points already angle towards each other and not parellel rendering a 180* yeild)

My fuzzy math tells me the Edelbrock miter design is far stronger in stress analysis using aprox two 20* bends totaling 40* since the mount brackets elevate it more straight accross on the towers. Plus it is retagaular at the miters with vertical surface joints

Dean

ps- the above mentioned round tube design is like that of BMR on the ends. I went back and noticed the one built on this page is a complete arch like the FEA model but the ends are miter cut flat onto the mount plates which is great- however, the FEA report may have been done just from flat bar end (like wall-to-wall rather than floor-to-floor mounting)

pss- Then back to the main topic of this dicussion about the 3pt leverag, the retangular design shines tieing into the main bar fore and aft wise once the Edelbrock brackets are box welded as I did mine.

 

Dean is correct. The models I used were the simplest shapes for comparing a curved piece of tubing to a sectioned piece. I was only curious which shape would be stronger with all other things being equal. In no way was I implying that the Edelbrock unit was inferior. However, if someone had more accurate dimensions of each, I wouldn't mind comparing the two designs.

From a design standpoint, I would be more concerned with fitment and mounting of the STB, not whether one style was 20x stiffer than no STB or only 19x stiffer.

 

Caleb, Very well said.

Obviously something is far better than nothing.

To reinterrate what I just posted as you were also posting is the 3rd pt leverage tieing into the 2pt laterally and its strength. This part I can tell everyone from first hand experience driving that alleviation of flex from the windshield area towards the towers diagonally is major.

I have driven mine a few times with just the 2pt Edelbrock bar with 3rd pt. bars removed (Why?- because I was doing some fuel and ignition work and removed only the rear links). I have ran it around town a few times without the 3pts and the car was LOOSE with JUST THAT REMOVAL. Now probably arrogant to say, but most of you would never feel any difference because of the weak links in most peoples cars. One bad componant will render failure or flex there rather than in a brace like this. My car was 100% built to par judging any of you against its 1.07g ability combined with my driving skills. I even had the seats in the car to feel the road better as well as a lighter weight and better biased vehicle to test with that was more nibble and sensitive

Trust me when I say I could remove any one of my 4 front lateral braces and notice a difference. You could remove one for me without me knowing which and I could tell you if you were faking me, or which one you actually did remove- that is how sensitive I could feel changes in this car. One rubber bushing left somewhere can destroy predictability on a linear scale. One weak componant, one section of weak chassis flex,....etc can all lead to diffent points of lateral failure when flex sets in- these weaknesses all add up to unpredictability from one corner to the next in changing road conditions and slop. You can not have any weak links or the failure will go there first and you will not have optimum tire grip for those tires used. Heck even a great suspension and chassis on crap tires does injustice.

Dean

I have given many quotes on here over the years, but here is the first time I will quote my favorite saying because it is one one point so frustrating and on this topic so true-
"Money makes the car fast, but not every fast car has a good driver".

 

Another thought just come to mind- I have quoted on here many time ,"Its not just what you buy but also how you set it up".

With that said, and the topic on hand about making parts, I often wonder many many times when I am giving advice to someone that just what problem on someones car do I not know about- what is hidden? What maybe even they no nothing about something else in their marraige chain of componants is causing greater weakness?

Without having someones car in fromt of you to inspect it thoughly, there is probably statiscally a 98% chance there is a weaker link somewhere that fails prior to the part on topic of discussion. Or, a part that is installed that is better than factory parts but adjusted wrong making it worse.

Case in point- lets take the original poster here that built the STB- 96IROC ( I am not picking on you solely, I am just using you as one example of hundreds on this board so please do not take this as any personal attack).

96IROC builds his own STB- great right- yes for the most part- In the right direction. Is it working...........guess what? No yet! It will when he finally hopefully reduces the more important weak link.
I have said this time and time again on these baords but with newer members coming on board and so many postings falling deep into the archieves, the points get lost and never seen unless reiterated. So here goes again...

Those STB's do absolutely NOTHING unless you first replace the crappy stock rubber bushing strut mounts.

WHY? argue with me all you want on how YOU PERSONALLY felt a difference on how your car feels- its mostly pyshcological. You might gain 10% of the parts overall potential, and 90% in the mind------ If you are this type of person, give me you car for a social experiment and I gaurantee I will win 95% of the time in a bet. Whats the bet? I could take just about anyones car here (there are a handful of knowledgable people here that do know there stuff in all do respect) and let you run your own car in autocross for a timed run, then secretly let me remove a aftermarket part of my choice you have puirchased and either replace it with a stock on, or just remove a part if nothing came stock, AND THEN let me adjust tire pressures and suspension settings and put you back into the seat for another run not knowing whether you first drove your setup, or my setup with one less/inferior part and I would bet big money each time that I would yeild the better timed run with you driving both runs.

Back to 96IROCS (and many other peoples)weak link.
That STB is doing NOTHING with those factory strut mounts still on there BECAUSE (lets look at what a STB does)
1) it holds the towers aprat under lateral cornering forces forcing the outer tower inward and changing camber(tire footprint) under flex.
2) the strut shaft is a critical suspension locator point on a MacPherson strut suspension
3) where does the strut shaft mount? In the strut mount.
4) does the strut mount flex? yes when it has rubber bushings
5) Will the strut SHAFT position change in a rubber mount...YES
6) If the STB is holding the tower from flexing, but the mount is fleing with the rubber bushing- then is the camber being helped by the STB - ABSOLUTELY NOT!

The strut shafts are sill closing gap even though the strut tower is not. Now any of you that think the metal chassis is weaker than the rubber bushing need to go back and study materials. The rubber will flex over changing camber enough till it can't flex no more against the end of lateral force and then ANY ADDITIONAL flex will be done by the tower flex- at this point the STB comes into play reducing maybe the last 10% of flex to give an assumption number. So Yes it did give feel....maybe.....but maybe 10% of what it could if you FIRST changed the strut mounts to solid bearing mounts.

The STB has the bling factor in the engine bay- thats why it sells.

Replace the strut mount and get 90% feel, then go after the last 10% with a STB. At that point, the strt towers will flex sooner due to the solid bearing mounts so by then the addition of a STB will feel more about 50% gain after strut mounts rather than a 10% gain before strut mounts- my math doesn't make sence? it should, Its why I am good at what I do.

Flex pecentages (In aproximation)
Worn out factory strut mounts, no STB......100% flex
Worn out factory strut mounts, with STB.....90% flex
new factory strut mounts, no STB...............75% flex
New factory strut mounts, with STB.............65% flex
Solid strut mounts, no STB..........................50% flex
Solid strut mounts, with STB.......................zero flex

I guess these figures to come into play at about .92g's. Up that to over 1g and these figures will change progressively worse with more sustained grip.

This is all lateral loading, has nothing to do with dynamic chassis loading of the towers under braking- this is where the 3pt comes into play for the most part. A triangulated 3rd pt also helps in lateral stiffness of the tower where it helps keep the towers not only equal distance at all times but from laterally flexing in sequence changing the outside and inside camber together. In other words- both towers can still flex together, just obviously not as much as one alone- this is still bad, its why triangulation is important from a 3rd pt mount in when EXTREME lateral forces and grip come into play- its called taking it to the next level. *This is a perfect example of something that was never a problem now becomes one*

Dean

 

OK.....

Where do we get new strut MOUNTS? Not the whole, aftermarket assembly, but just metal (spherical?) mounts, to put in the stock mounts?

 

Why wouldn't you just buy the whole aftermarket assembly? Anyways;

http://www.ground-control-store.com/.../II=134/CA=181

I think I've seen other ones also, but I'll let you waste your time searching if you really care, instead of wasting my own.

 

Gimme your wallet & I'll be glad to go fully aftermarket. Not everyone has the monetary resources to go "all out".

Think about that, before you go off, the way you did.

Nobody even asked YOU to "waste your time" posting your useless post. So why did you???

 

well, considering what the ground control inserts cost, it would be better to just buy the hotpart, or spohn strut mounts at a lower price. Unless you are restricted to the GC parts due to a rules in a specific racing class.

I dont think i've ever seen another insert aside form GC's.

 

well said dean.

lol, makes me realize how far I have to go with my car in the next couple of years.

 

Pretty good thoughts, Dean.

A chain is only as strong as its weakest link. That sort of applies to stiffness as well as strength. Fix the softest link first, if you're going for any real improvement. As you note, bushing compliance can bury any improvements that you think you're making in things that are already more rigid than rubber. Rubber and its compliance works OK on the street because very few people ever drive hard enough for it to matter. I doubt that one person in 10,000 ever intentionally drives past 0.5 lateral g. Fewer still go up there often enough to be able to pay attention to what's going on with the car's chassis.

There is one mostly street-driving related exception regarding improvement that can be felt from adding only a STB (of any description), and that's a reduction in noise/vibration/harshness that can come from adding just little bits of stiffness in the right places. This won't mean that the chassis is particularly stiffer overall, just enough locally to eliminate bothersome structural vibrations or move them up to frequencies where they aren't as noticeable. This is a benefit that can occur, not something that is absolutely guaranteed.


It doesn't directly apply to this STB discussion, but chassis bracket stiffness can be almost as low as bushing stiffness (and can throw things like overall stiffness and camber control nearly as far out the same window). I have it on pretty good authority - an engineer employed by an OE mfr - that some chassis brackets are only good for ~15,000 lb/in stiffness. OE rubber bushings can be 10,000 lb/in. I'm not saying that F-body brackets are this flexible, just that brackets in general very definitely aren't as rigid as you might think they are by trying to bend them by hand.


Norm

 

From Ground Control, regarding a STB.....

"Upper Stress Bars --- These A/S and S.P. legal stress bars are absolutely necessary to prevent excess flex of the front MacPherson strut towers. It is very common for the sheet-metal to deflect 1/4” or even more, causing unwanted changes in camber. Our upper stress bars are manufactured from .120 wall Milspec 4130 chrome-moly tubing, and are of the highest quality possible."

 

I'll give you a better reason... they offset where the strut mounts in the strut mount. That's wonderful and everything, but like other modifications to do the same thing, whether we’re talking about offset inserts, strut mounts designed to offset the strut location or just extending the slots in the towers, by the time you get it to someplace that it really helps things you’ve got the strut rod by the side of the hole in the top of the strut tower.

You could ditch the shield or an aftermarket boot from around the shaft, but it’s probably not a great idea on a car that will see actual street use/real weather. Cutting the hole larger doesn’t help because now you’re weakening the strut tower by removing the reinforcing lip on the hole.

Anyway, if anyone knows of an appropriate bushing/bearing to use to hold the end of a strut I’d love to hear about it, I’m sure plenty of us could figure something out to hold it.

 

Better reason for what? You quoted me, yet I see nothing in your Reply, that applies to my post, that you quoted.

 

Many thanks for that statement. Are you listening, Stephen?

JamesC