Front Strut Bar Number Crunching

[Convette]

This isn't supposed to be a thread about what they do. You've said a lot things in your time on here most of which discredit you, and especially your knowledge. We all understand that your a anti strut bar activist. This thread doesn't apply to you.

[JohnnyWadd]

This isn't supposed to be a thread about what they do. You've said a lot things in your time on here most of which discredit you, and especially your knowledge. We all understand that your a anti strut bar activist. This thread doesn't apply to you.

 

Word.

[patra_is_here]

wow guys good points. I guess strut tower bars really do help performance. thanks for your incredibly detailed and mathematically sound explanation. you've proven that your car gets much better lap times.

[Komeuppance]

Obviously Clay needs this broken down into easy to understand terms. Our last "debate" ended with me saying the words "Nachos Supreme, Cutlass Supreme".

 

What type of suspension does the Starion have??

http://www.projectzerog.com/archives/ZeroGversion1/images/frontsuspension.gif

McPherson strut type independent suspension

 

What is the purpose of a strut tower brace??

A strut bar, strut brace, or strut tower brace (STB) is a mostly aftermarket car suspension accessory usually used in conjunction with MacPherson struts on monocoque or unibody chassis to provide extra stiffness between the strut towers.

 

With a MacPherson strut suspension system where the spring and shock absorber are combined in the one suspension unit, the entire vertical suspension load is transmitted to the top of the vehicle's strut tower, unlike a double wishbone suspension where the spring and shock absorber may share the load separately. In general terms, a strut tower in a monocoque chassis is a reinforced portion of the inner wheel well and is not necessarily directly connected to the main chassis rails. For this reason there is inherent flex within the strut towers relative to the chassis rails.

 

A strut bar is designed to reduce this strut tower flex by tying two parallel strut towers together. This transmits the load of each strut tower during cornering via tension and compression of the strut bar which shares the load between both towers and reduces chassis flex.

 

On the Saab Sonett mk2 and mk3 the overflow container for the cooling system doubles as a strut bar. The longnose version of the Saab 96 also came with a factory mounted strut bar. This despite that both cars used double wishbone suspension.

 

Following the aftermarket's lead, some manufacturers have started fitting strut bars to performance models, including the Honda Crosstour, Pontiac GTO, Pontiac Bonneville GXP, Nissan Skyline, Nissan 350Z, Mazda RX-8, Acura CL Type-S, Acura TSX, Daihatsu Charade GTti, BMW M3, Mitsubishi Lancer Evolution, Mitsubishi Outlander, Mitsubishi Colt Ralliart, Toyota MR2, Toyota Solara, Toyota Camry SE, Ford Mustang Bullitt, Volvo S60, Mazda Protege 5 and the Holden VY II Commodore, as standard equipment.

http://en.wikipedia.org/wiki/Strut_bar

 

So why would you want to reduce chassis flex??

When a chassis flexes it does not do so linearly. Chassis flex also changes suspension geometry which effects your camber, caster, and toe. This results in unpredictable, and unstable handling. Stiffening the chassis as much as possible allows one to tune suspension settings with a more consistent and safe response.

 

-Robert

[TexasTieaga]

Obviously Clay needs this broken down into easy to understand terms. Our last "debate" ended with me saying the words "Nachos Supreme, Cutlass Supreme".

 

What type of suspension does the Starion have??

http://www.projectzerog.com/archives/ZeroGversion1/images/frontsuspension.gif

McPherson strut type independent suspension

 

What is the purpose of a strut tower brace??

 

http://en.wikipedia.org/wiki/Strut_bar

 

So why would you want to reduce chassis flex??

When a chassis flexes it does not do so linearly. Chassis flex also changes suspension geometry which effects your camber, caster, and toe. This results in unpredictable, and unstable handling. Stiffening the chassis as much as possible allows one to tune suspension settings with a more consistent and safe response.

 

-Robert

 

Nicely done

[Foreverzero]

John: Bingo

 

Komeuppance: <3

 

 

As to the pertaining topic, I think a good starting place would be the 240sx. S13 and S14. I've got a couple friends with both so I'm gonna see if I can get some numbers hashed out this week and go from there.

[patra_is_here]

jesus christ. I know to understand to great detail how our suspension works and the loads involved. i wiki quote is not informing me of anything new. I have full comprehension of the theory of strut bars. my whole point, and i don't know how many times i need to emphasize this, is that it's nearly pointless on our cars.

 

here's a horrible drawing i did

http://farm6.static.flickr.com/5217/5385825590_22a885196f.jpg

 

the two little circles represent where the struts bolt to the towers.

 

so, the area in the front is the upper and lower radiator support area. the rear is the firewall. left and right are the shock towers with sheet metal. back is the firewall.

 

the top rails left and right are boxed tubular sections, not just sheet metal.

 

the entire front of the car is a steel framed cube-like shape, with sheet metal tying together the load bearing planes. it's very similar to a monocoque frame in that respect. the reason strut bars are all but totally pointless is because the entire firewall section of the car is doing the job of keeping the shock towers in place as well as the upper square tube sections, which are tied-in front and rear, with the core support and firewall structure. you understand that any plane covered in sheet metal is essentially the same as an open plane with triangulated cross bracing?

 

no one has seen any evidence to imply that the towers are moving on these cars in any amount that would some how effect handling it.

 

the logic is so damn simple yet you all refuse to follow it. you just aren't putting the kind of load into the towers that is going to effect performance.

 

 

i apologize for thread jacking.

Edited January 24, 2011 by patra_is_here

[Technology]

What if you pop a wheelie? When you land, you will be putting the kind of load on the strut towers that will require a bar.

[JohnnyWadd]

no one has seen any evidence to imply that the towers are moving on these cars in any amount that would some how effect handling it.

 

the logic is so damn simple yet you all refuse to follow it. you just aren't putting the kind of load into the towers that is going to effect performance

 

Exactly how much movement is needed to affect performance?

 

So where is the load going?

 

What was your job at the shop you worked at?

[Komeuppance]

jesus christ. I know to understand to great detail how our suspension works and the loads involved. i wiki quote is not informing me of anything new. I have full comprehension of the theory of strut bars. my whole point, and i don't know how many times i need to emphasize this, is that it's nearly pointless on our cars.

 

here's a horrible drawing i did

http://farm6.static.flickr.com/5217/5385825590_22a885196f.jpg

 

the two little circles represent where the struts bolt to the towers.

 

so, the area in the front is the upper and lower radiator support area. the rear is the firewall. left and right are the shock towers with sheet metal. back is the firewall.

 

the top rails left and right are boxed tubular sections, not just sheet metal.

 

the entire front of the car is a steel framed cube-like shape, with sheet metal tying together the load bearing planes. it's very similar to a monocoque frame in that respect. the reason strut bars are all but totally pointless is because the entire firewall section of the car is doing the job of keeping the shock towers in place as well as the upper square tube sections, which are tied-in front and rear, with the core support and firewall structure. you understand that any plane covered in sheet metal is essentially the same as an open plane with triangulated cross bracing?

 

no one has seen any evidence to imply that the towers are moving on these cars in any amount that would some how effect handling it.

 

the logic is so damn simple yet you all refuse to follow it. you just aren't putting the kind of load into the towers that is going to effect performance.

 

 

i apologize for thread jacking.

 

The principle of a strut tower brace is too simple for you to understand then. Add another brace = more strength and less flex. It can't get anymore simple than that. Your ego is getting in the way perhaps.

 

Evidence: The towers move when you jack the car up, it's obvious when you try to install a strut brace. The chassis flexes when you jack the car up at one point as well. Take a look at your door panel gaps.

 

You keep going on and on... and ON... about how the Starion is very stiff already. Yes, we agree. Well, it will be even stiffer still by adding another brace. This is the point you seem to be missing. Mitsubishi/Ralliart installed strut tower bars on both racing (track, rally) versions of their Starions. Professional racing engineers saw benefits of added bracing to the chassis.

 

Here's a few jabs at you... you're just not driving the car hard enough to need a strut bar. Or you aren't an experienced enough driver to take advantage of a stiffer chassis. Should I even go as far as saying you are acting quite ignorant?? If you want to continue your "modifications" at a novice level, then that's your choice to stay an amateur.

 

-Robert

[patra_is_here]

You keep going on and on... and ON... about how the Starion is very stiff already. Yes, we agree. Well, it will be even stiffer still by adding another brace. This is the point you seem to be missing. Mitsubishi/Ralliart installed strut tower bars on both racing (track, rally) versions of their Starions. Professional racing engineers saw benefits of added bracing to the chassis.

 

 

 

thank you for summarizing my point. from day one, threads and threads ago i've said that unless you've got a racecar the strut tower brace is essentially pointless.

 

track cars and rally cars see much higher loads. those cars get jumped. they have massive slicks. they bounce off the berms. but, that being said, we still don't know what benefit it actually caused. for all any of us know they could have overbuilt just to be on the safe side (which is fine imho). they could have cut up the front section to allow for the rally front, so the front of the wasn't as rigid.

 

that fact that something gets placed on a racecar or production car isn't evidence that it works. hell, people used to build racecars will long organic looking swooping lines (lambo miura, jag e type, etc) until someone figured out that these swooping curves are actually worsening performance by creating lift at high speeds and causing the vehicles to lose traction.

 

i will now tackle your other point in another post.

[Convette]

I have a race car, so I guess it'll work fine on my car.... lol

 

heres a pointless mod... mud flaps and louvers.

[patra_is_here]

The principle of a strut tower brace is too simple for you to understand then. Add another brace = more strength and less flex. It can't get anymore simple than that. Your ego is getting in the way perhaps.

 

Evidence: The towers move when you jack the car up, it's obvious when you try to install a strut brace. The chassis flexes when you jack the car up at one point as well. Take a look at your door panel gaps.

 

 

here's is an over simplified drawing.

 

http://farm6.static.flickr.com/5216/5388030354_3d8ef3c477.jpg

 

the circles are the wheels. the squares represent both front and rear chassis sections, with strut bars.

 

the parallel lines represent the rest of the chassis. I choose the lines because i wanted to make it incredibly simple, so it is very easy to visualize. this is the 'worst case' sort of example, since all chassis are some bit stronger than two lines lol.

 

so, according the the drawing, you now have stiff front and rear chassis sections, but they are both still the same level of independence from each other. the braces don't seem to be effecting the middle section of the chassis, and thats the very section that flexes the most (as you illustrated with your door example).

 

so keeping the towers together helps with how much lengthwise twist of the chassis?

 

 

 

so, here we are again, i've covered nearly every base i can think of, used idealized versions to aid in any explanation and visualization. I'm done. I know everyone will be real happy. If at this point you think they are still a worthwhile mod, then knock yourself out. the SQ community is pretty solid at dispelling bad mods or things that don't work. but i gotta be honest, you put up an exhausting fight.

 

anyhow, if someone wants a brace, have at it. it'll look cool that's for sure. maybe it'll help an otherwise already weakened starion. maybe someone had some damage to the frame. maybe it's rusted. maybe the radiator core supports have been removed. i've officially stopped caring about this thread. you won. you all won.

[patra_is_here]

I have a race car, so I guess it'll work fine on my car.... lol

 

heres a pointless mod... mud flaps and louvers.

 

don't you have a full cage already? didn't you cut up sections of your firewall and front chassis? you should probably have a tower brace.

[JohnnyWadd]

Exactly how much movement is needed to affect performance?

 

So where is the load going?

 

What was your job at the shop you worked at?

 

 

No answer?

 

here's is an over simplified drawing.

 

http://farm6.static.flickr.com/5216/5388030354_3d8ef3c477.jpg

 

Oh i see the roller bearin right there in the middle of the car, now it is clear, only the center of the car flexes, hmm that must be why these cars are such good rock crawlers.

 

http://img23.imageshack.us/img23/315/stickt.th.jpg

Edited January 25, 2011 by JohnnyWadd

[patra_is_here]

No answer?

 

Oh i see the roller bearin right there in the middle of the car, now it is clear, only the center of the car flexes, hmm that must be why these cars are such good rock crawlers.

 

 

man you are such a smart-tail that it's like talking to a 16 year old. the single axis of twist is idealized (which i've already stated). no matter how you think the chassis is gonna twist, you can find a single point at each end and draw a straight line between then to approximate any axial twist. it's not something i made up. it's the way engineers approximate stuff in order to express it mathematically.

 

 

and, now the answers to the other questions (even though i wanted to be done, i suppose I can help you learn something)

 

the amount of movement needed to affect performance would have to be enough camber change during cornering to alter the contact patch of the tire greater than the amount that the tire can conform to counteract. since none of these cars are set up with such precision or driven in such precise circumstances the whole issue becomes moot.

 

'where is load going'. the vertical force exerted by the road on to the car and it's components is absorbed by the spring. the spring takes energy to compress. the energy that is used to compress the spring is directly related to the energy transfer of the car going around the corner very fast. now i know the phrase "the vertical force exerted by the road on to the car" might sound weird to you, but it's the way it's expressed in engineering circles, it is the exact same amount of energy that the car is pushing down on the road. everything has an equal but opposite force.

 

so, the load is taken by the spring. now, if you run softer springs, they absorbed more frequent load changes until their threshold is reached (thats why soft springs have a smoother ride, because the energy from road irregularities is being absorbed by the spring, not being transferred to the chassis.) when the threshold is reached, the spring is compressed all the way and your struts are bottoming at. at this point all load is transferred to the chassis.

 

if you run high rate springs , more of the smaller loads are transferred to the chassis, until you reach the point where the spring starts to actually compress more and absorb the energy. hence, a rough ride. in both cases, until the load exceeds the threshold of the spring, the spring will be doing work to lessen the load that is transferred to the chassis.

 

now your other question. the portion of my job, as it relates to this discussion, was setting up cars for track days, setting alignment, doing tech inspections, working as a pit crew member during races and track days. the vehicles i've had a chance to drive on track were IT class 510's and spec miatas. both with incredible grip. both with nearly zero suspension travel (both sitting on bump stops), and both cars ran winning times with experienced drivers, despite neither car have a strut bar. even the flimsy 510 didn't have a strut bar for many of the races. but they both had full cages.

 

not that i think any of this explanation matters to you. you're still going to disagree, and you're still going to find an unrelated 'flaw' in the statements. the reason i put 'flaw' in quotes, is so far all the 'flaws' you have tried to use against me have been due to your lack of understanding of proper debate and correct engineering discussions. you argue like a dummy. I have been as direct and thought out as i can be. I have given examples, given illustrations, explained the essence of the physics involved. you've called me names, taken my words out of context, changed the intent of my statements, and continue to mock any intelligence poured in to this discussion.

 

I would post a few other words here but the filter doesn't allow it.

[Komeuppance]

here's is an over simplified drawing.

 

http://farm6.static.flickr.com/5216/5388030354_3d8ef3c477.jpg

 

the circles are the wheels. the squares represent both front and rear chassis sections, with strut bars.

 

the parallel lines represent the rest of the chassis. I choose the lines because i wanted to make it incredibly simple, so it is very easy to visualize. this is the 'worst case' sort of example, since all chassis are some bit stronger than two lines lol.

 

so, according the the drawing, you now have stiff front and rear chassis sections, but they are both still the same level of independence from each other. the braces don't seem to be effecting the middle section of the chassis, and thats the very section that flexes the most (as you illustrated with your door example).

 

so keeping the towers together helps with how much lengthwise twist of the chassis?

 

 

 

so, here we are again, i've covered nearly every base i can think of, used idealized versions to aid in any explanation and visualization. I'm done. I know everyone will be real happy. If at this point you think they are still a worthwhile mod, then knock yourself out. the SQ community is pretty solid at dispelling bad mods or things that don't work. but i gotta be honest, you put up an exhausting fight.

 

anyhow, if someone wants a brace, have at it. it'll look cool that's for sure. maybe it'll help an otherwise already weakened starion. maybe someone had some damage to the frame. maybe it's rusted. maybe the radiator core supports have been removed. i've officially stopped caring about this thread. you won. you all won.

 

You are arguing about something completely different. Here's some verbiage for you to take in:

 

Any change in the suspension's geometry is bad.

 

The strut towers flex easily, take some measurements instead of just blindly refuting it.

 

We didn't win, you just are a loser!! (Sarcasm font in case you didn't notice.)

 

-Robert

[patra_is_here]

You are arguing about something completely different. Here's some verbiage for you to take in:

 

Any change in the suspension's geometry is bad.

 

The strut towers flex easily, take some measurements instead of just blindly refuting it.

 

We didn't win, you just are a loser!! (Sarcasm font in case you didn't notice.)

 

-Robert

 

hahaha robert your posts always make me laugh.

 

how about this, i'll take measurements instead of blindly refuting it, if you take measurements instead of blindly accepting it.

 

word to your mother.

[JohnnyWadd]

i've officially stopped caring about this thread. you won. you all won.

 

Liar.

 

that fact that something gets placed on a racecar or production car isn't evidence that it works.

 

No we should go off of what you say instead becuase you worked at a shop and checked air pressure on cars that rode on bump stops. LOL

 

now your other question. the portion of my job, as it relates to this discussion, was setting up cars for track days, setting alignment, doing tech inspections, working as a pit crew member during races and track days. the vehicles i've had a chance to drive on track were IT class 510's and spec miatas. both with incredible grip. both with nearly zero suspension travel (both sitting on bump stops), and both cars ran winning times with experienced drivers, despite neither car have a strut bar. even the flimsy 510 didn't have a strut bar for many of the races. but they both had full cages.

 

Full cages? Well ya at that level a strut brace is not needed. How many of us have full cages in our starions? They rode on bump stops? That is stupid. Riding on bump stops is no way to set up for track. You need some travel of the suspension. Obviously you are either clueless are you are just making up the zero travel thing. A track car needs travel to soak up body roll or it will just tip over. Especially with a perfect track and high grip tires. Riding on bump stops means bounce, some people know that. Some dont.

 

I would post a few other words here but the filter doesn't allow it.

 

Typical thing for a condescenting type person like you to say

 

man you are such a smart-tail

 

I may be a smart ax, but better than being a dumb ax, like you.

 

and, now the answers to the other questions (even though i wanted to be done, i suppose I can help you learn something)

 

Here is a quick drawing to show what you have taught me.

http://img194.imageshack.us/img194/3595/20110125192608.th.jpg

 

'where is load going'. the vertical force exerted by the road on to the car and it's components is absorbed by the spring. the spring takes energy to compress. the energy that is used to compress the spring is directly related to the energy transfer of the car going around the corner very fast. now i know the phrase "the vertical force exerted by the road on to the car" might sound weird to you, but it's the way it's expressed in engineering circles, it is the exact same amount of energy that the car is pushing down on the road. everything has an equal but opposite force.

 

so, the load is taken by the spring. now, if you run softer springs, they absorbed more frequent load changes until their threshold is reached (thats why soft springs have a smoother ride, because the energy from road irregularities is being absorbed by the spring, not being transferred to the chassis.) when the threshold is reached, the spring is compressed all the way and your struts are bottoming at. at this point all load is transferred to the chassis.

 

Oh the "chasis". So now umm are the strut tower part of the chassis? I thought so. But you said they dont get any load earlier, now you say they do? Or are you saying they dont? Unclear. Contradicting.

 

the amount of movement needed to affect performance would have to be enough camber change during cornering to alter the contact patch of the tire greater than the amount that the tire can conform to counteract. since none of these cars are set up with such precision or driven in such precise circumstances the whole issue becomes moot.

 

Wrong. Any Movemen will affect performance. Performance has to do with how things work,in any situtaion, not with special presicion or complex ratio or tires contact patch in relation to sidewall flex. Thats like saying we dont need good tire because the contact patch will change and the chassis will have axial flex before traction can be broke.Performance=It could be a sudden lane change on the highway when a SPEC MIATA pulls out in front of you.It could be that littel exta steering feel and feedback that lets you enter a corner with more confidence and not snap oversteer and put it in the ditch. Tell me that point is moot? Wrong.

 

Here is the correct answer

Any change in the suspension's geometry is bad.

-Robert

 

That is true for changes that you dont make happen on purpose like when you punch it and slide around a corner or when you roll off the gas to keep the rear end planted...that precision...some of drive our cars like that...some of us...well you know..

 

hahaha robert your posts always make me laugh.

how about this, i'll take measurements instead of blindly refuting it, if you take measurements instead of blindly accepting it.

word to your mother.

 

LOL the guy that brags about hius quantum engineering smarts cant be bothered to take a measurement. Probably needs a class on how to operate a tape measure.

Edited January 26, 2011 by JohnnyWadd

[Komeuppance]

hahaha robert your posts always make me laugh.

 

how about this, i'll take measurements instead of blindly refuting it, if you take measurements instead of blindly accepting it.

 

word to your mother.

 

I already did take measurements when I lifted my car up, I noticed the difference.

 

You want it quick and nimble with a high hat, and a souped up tempo.

 

-Robert

[Convette]

Hahaha internet wars....lol

[TexasTieaga]

Here's an idea. Instead of crappy drawings and examples and given circumstances and all this quantum physics talk (which quantum physics deals on a sub-molecular level which scientists can't explain. What does it have to do with strut tower bars? Can one SB simultaneously exist in another place at once?) some one just make a STB out of aluminum foil and go for a very spirited drive, posting before and after pictures, and let's see if the foil STB is all messed up or if it retains 100% of its original shape. I'd do it myself but I am without working vehicle for now. Seriously, let's get some proof. Otherwise you're not allowed to post here without saying something outrageous like Knuckles can beat Sonic in a footrace and Tails can't really fly, he just glides for prolonged periods of time, even when stationary in air. He's gliding still.

[patra_is_here]

no one is posting quantum anything. I was just giving a list of any experience i've had solved multi-tiered problems. at no point did i focus on quantum mechanics. The list of classes I gave are the required classes for all engineering students at the lower division level. that's all.

 

i like the foil idea. I had considered doing one out of balsa wood, but then i realized that underhood turbulence might cause some issues.

 

robert, the reason the doors become harder to open is because the doors are load-bearing. they are meant to be closed while driving the car, as they add to the rigidity of the chassis. therefore, if you apply load to the chassis, and then try to open the door, of course it's going to be difficult, because the doors are under load. if you look at the B-pillar, you can see there are two distinct points of contact for the door, which is all you need to create a rigid system.

 

but regardless, we aren't driving F1 cars, we don't have massive slicks, we don't have tons of downforce and a razor's edge handling characteristic indicative of a precise machine. we have 25 year old mitsubishi starions. every bit of chassis flex doesn't hurt us. every minor suspension change doesn't effect us. the machines and the use of them just aren't precise enough.

 

not that any of this matters anymore. people like the tower bars because they look cool or they think it matters.

[Komeuppance]

Psh, don't be jealous Clay... just because my junk gets STIFFER than yours.

 

In the end, that's all that matters... to the ladies.

 

-Robert

[Komeuppance]

no one is posting quantum anything. I was just giving a list of any experience i've had solved multi-tiered problems. at no point did i focus on quantum mechanics. The list of classes I gave are the required classes for all engineering students at the lower division level. that's all.

 

i like the foil idea. I had considered doing one out of balsa wood, but then i realized that underhood turbulence might cause some issues.

 

robert, the reason the doors become harder to open is because the doors are load-bearing. they are meant to be closed while driving the car, as they add to the rigidity of the chassis. therefore, if you apply load to the chassis, and then try to open the door, of course it's going to be difficult, because the doors are under load. if you look at the B-pillar, you can see there are two distinct points of contact for the door, which is all you need to create a rigid system.

 

but regardless, we aren't driving F1 cars, we don't have massive slicks, we don't have tons of downforce and a razor's edge handling characteristic indicative of a precise machine. we have 25 year old mitsubishi starions. every bit of chassis flex doesn't hurt us. every minor suspension change doesn't effect us. the machines and the use of them just aren't precise enough.

 

not that any of this matters anymore. people like the tower bars because they look cool or they think it matters.

 

Ha, I just saw your other post about threads turning into "un-scientific approach" and it warrants a reply here as well... plus I'll actually read the drivel you've just spewed out.

 

Here's a good scientific answer for you:

 

Second is not first.

 

BOOM, SCIENCE AND MATHEMATICS!!

 

/end class

 

-Robert