I'm trying to figure this out. Does a strut brace really help, or does it just seem like it does? I know my car seems to run better after an oil change, but I know it can't. I wonder if the same is true for a strut brace. When I look at the rubber bushing at the top of the strut and think about how much it will deflect under load, then look at the body work and imagine how much force it would take to cause it to deflect a meaningful amount... it seems that as long as the rubber bushings are there, a strut brace would fix a non-existant problem (on a steet car). Anybody have any concrete evidence to prove they help or don't help? I was planning to build one to triangulate to the firewall, but I think I've just talked myself out of it. Thanks for any input...

Kerry

 

you are right in a sense. the larger the problem the more effective it will be. with the stock suspension, the strut brace will have little effect because the deflection is being absorbed by the soft saspension components. as you upgrade to a tight suspension then these forces will be stronger on the frame so it becomes a weak point. street or race makes no difference, its how hard you drive and how you've tuned. if you have the extra money or capability to make your own then why not. there aren't any downside except weight. plus a stiff chassis is always good just for control and feel. it will just show much more the tighter your suspension.

 

I would say that it would make a difference when you are running r compound tires and they are sticking well, then it might throw the alignment off a little. But on street tires....the tires would break loose before it became a factor. Well the human mind can trick the body to thing anything. An oil change might make the car feel faster. But in reality it is just you feeling good about the oil change. Same reasons hypochondraics(sp?) get placebos(sp?) instead of real drugs, its all in the head sometimes.

 

how would the strut tower bar affect the alignment? we're not bending the strut towers past the metal's yield point. i'm not following your thought here.

 

Therotically under extreme g-forces (racing with r-compound tires) the weight of the car in a turn on the strut will cause the top of the strut to pull outwards making the tire have less contact with the road. This force is changing the alignment from its origional settings. The strut brace ties both towers together to keep the strut from pulling away from the car in a turn. I don't know about you but those are some extreeme forces.

 

the only thing that might change is if the 4 mounting bolts move around in the holes due to tolerance oversizing. if you've changed the alignment by bending the metal, the give me some of those tires. you will flip the car cornering that hard before you band the towers unless you clip a curb or something that would cause a force spike.

 

ok, i read again. you are saying that while cornering the flex of the tower will cause the alignment to change. i gotcha. i was thinking permanently. that was what i was saying before. it depends on how tight your suspension (including tires) is. "its not how you stand by your car, its how you drive your car."

 

I agree with Kerry and jbontke... but I've kept it to myself until now. Allthough I understand the theory behind strut bars, I doubt they have any real effect on a street car... not to the point that you could "feel" anyway (talking RX-7's here... some cars are pretty bendy). On the other hand, a race car could probably benefit from some stiffness taken away by fibre glass body panels and weight reduction.

Still, for me it comes down to adding something pretty heavy to my car for some "questionable" gains... that's why I dont have one .

 

with a unibody design, i would imagine that our cars are fairly stiff to start with. so it would take a hell of a lot of power, or force, to actually move the strut towers..
or am i way off here?

 

uni-bodies are pretty stiff, but very car to car. my camry was a little flexy, my girlfriend's maxima is pretty flexy, my wrx was like a rock. i don't like the track, street comparison because it depends on the track or street you're on. its how hard you are and the forces you put on the chassis. whether its through canyon whoops, or around a sweeping lefthander and laguna seca. it also depends on what you value more, weight savings or stiffness. the tighter chassis will be more reassuring and allow better handling were as the more weight will lower grip holding capabilities. of course the last one voids if you are incountering extreme forces that deflect the suspension enough to cause the tire alignment to be unsatisfactory. also there are multiplications here that add up, a tolerance stack up. the bushings deflect ,the tower deflects, and the tires deflect. you are trying to minimize all these. polyurethane bushings, lower ratio sidewalls, strut tower bar. now, the extent of how far you want to go and what is optimal for you is a result of a variety factors. i drive very hard and rally at land between the lakes. i actually had slight bend marks in the camry's towers from the spiking forces of cornering on rutted gravel roads. now before you say its roads not extreme like that, look at autocrossing or hammering through some backroads. for those that push very hard and/or run a tight setup (r-compound, higher rate springs, bushings, tighter damping) will see these higher forces deflecting the towers to a degree. look down at the shock tower and there is just a horizontal line of metal there. attaching the 2 together will assure that the higher deflection in the outide tower will be translated over to the inside tower as well, which is seeing lower forces. this helps, but then you step up to the triangulated bar which also now has to try and pull the fire wall with it, as well as the inside shock tower. now there is another factor on top of this, the stiffness of the bar. the bar will hav a certain amount of flew and tension pull itself. material and construction play a major factor in the effectiveness. a good bar should have negligable flex compared to the outside tower and inside tower movement. the triangle bar will of course see a lot more force then the strut tower bar but will but will also be more effective as noted.

 

Lot's of theorising, but not really any answers...

I think I'm going to have to come up with some form of device to see just how much the towers are flexing around under heavy cornering.

Has anyone ever snapped a strut bar? You'd think that if they where subjected to so many forces, they would sometimes fail... hmm...

 

buy something that will stretch under, say, 10 or so pounds of pressure. hook to the bolts on either side. make sure that it doesn't have a high yield point as we don't want it to stretch under force and then return to its original position. it can't be very heat sensitive either. or you could run a rod out even with the tower, run a force/weight guage between the bar and tower. make sure the gauge has the capiability of marking the peak measurement, then go drive hard. when you get back take the peak force measurement and how far it moved.

the reason there don't seem to be any answers is its not a black and white question. there also aren't enough facts. i haven't been able to drive my rex yet (still have a clogged tank) so i can't compare its flex to the other cars. i guess the best way is if you can borrow one, throw it on and try it out. if you like it buy one, if not then don't. all i did was shed light on the basis behind it and whether YOU, as the driver, think it would be benificial to your car and the way or how you drive.

 

The FB is not as stiff as you might think. I just got done with a major suspenion rebuild on my 84 se and in the process of doing the wrok myself I saw first hand how well they work in preventing front end flexing/twisting. Here's how I know. I had the whole car on jackstands while I did the rebuild. The car still had all stock parts on it that were shot so I went with the following-

-ebiach springs
-tockio's ( blues )
-full suspension tech sway bar kit
-energy suspenion bushings
-and of course a front strut tower bar.

The bar I got is the one guru sells on this forum in the parts section ( do a search for his user name and you'll find the like to the sites with pics and info). I am pleased with the piece, he makes them himself, and it's not some thin alloy bar. It's 1/8 steel and weighs about 6 or 7 pounds. I tried to install this bar while the car was still up on stands but it wouldn't fit. All the studs didn't line up with the wholes in the strut bar ( by as much as 1/4"!!) I was mad that I had bought something that was made poorly ( so I thought ). When I had everything on and bolted down I got the car back on the ground and tried to install the bar again, no luck. The next day I thought, " what the heck" and tried again. It fit PERFECT! this whole time the car had just sat there, I hadn't even started it yet. So you see there is quite a bit of flex to be taken out of the front of an FB.

 

they look good too

 

Don't forget he has like 250 HP and 300 ftlbs torque from a 302. So bendage is a bit easier. I am paying real close attention to this as I may need one.

 

Very interesting, rex alot. I would never have dreamed that could happen. But I think you just talked me into building something. Maybe I'll build one intentionally weak to start with and see of it gets wadded up.

Kerry

 

I just took a look at my auto-X video's from last season and in one particular instant during hard cornering, the car comes about and can be seen dead on by the front, when I looked at it in slow motion I could have sworn I saw the front end twisting

I was running a stock setup with Toyo Ra-1's at the time

Anyway I will check the video once again to make sure but lets say that it got me thinking about those strut tower braces.

Those R-compounds have been quite rough on my cars chassis (not that it was in perfect shape before)

 

ask ajc13b about his car twisting on launch,

you can see it in some of his photos,
i thought that strut tower bar was more at home on the drag strip anyway,

its always a must for big time muscle cars to help from twising the frame,

so the bar is effective,
but the question is does your car have what it takes to make it serve its purpose?


i also seen where someone took a strut tower brace and tied it into a racingbeat engine brace,
now that was both very cool looking and efective.,

anyone can see an engine torque,
all you have to do is hit the gas,

less twist means more put to the rear end,
which means more put to the ground,

but then again the saying is,
"when you start hooking up and eliminating slop is when you start breaking things"

very very true

 

i thought their purpose was to stiffen up the front end during hard cornering, not straight line accelerating.

 

it has multiple uses,

it helps to prevent frame twist during extreme acceleration,

 

most people use it for hard cornering but it is used by drag racers also.

 

tie a peice of string between the two strut towers. If it breaks, you know that they flex a lot. Use something that wont stretch much, like cotton string or dental floss.

 

GOOOD IDEA I am gonna have to try that I will do it tomarrow, and run like hell around corners

COOL, THANX LATERZ, Andrew

 

that will tell you if they flex out.. but nothing about inward flex. (if that would even happen?)

 

I think youll find a strut tower bar does more work of keeping the towers apart (stops the strut tower moving inwards with the load of the spring) than stoping them from spreading...


and in my experiance they defantly do work, but more so on some cars than others.