Carbon fiber Strut bars...

[seth98es]

Does anyone have these? I was thinking of getting them but do not know the quality of them. They look like they are made out of real CF, I just dont want to get stuck with a crappy overlay sticker hehe

 

[Defiant]

Well, they sure look exactly like the cheapies with covering on them- the shape of the bar, the taper on the ends, the mounts and screws are just like the ones I got..... for less than they're charging for shipping.

Let's guess what the functional difference might be.....

 

[seth98es]

hehe yah they are kinda expensive. I think I will just stick with one of the $7 adjustable ones they have on eBay...

 

[Morphius]

Those look like overlays, but who knows.

Even if they were Carbon fiber, I'd never buy one. Carbon Fiber is weak in compression. This is what your strut bar is trying to combat, movement of the strut towers inboard. When that happens, you're putting the strut bar in compression. You'd get much better response out of a steel or aluminum version. Personally, I'd go with steel.

 

[HondaKilla]

Well from my experience with several strut bars for my 240sx, most of them are just aluminum with overlay or aluminum with actcual c/f over it. All it really is, is a cosmetic thing and no benefits but looks. Many will disagree but I wouldnt go cheap on strut bars but I wouldnt get real expensive with them either. I'd say the reason most people say that strut bars dont really do much is because all they have used is cheap strut bars. From my experience they have a nice effect when useing nice quality strut bars and compliment a nice suspension very well in hard acceleration turning!

 

[Wildflyer897]

i got those CF strut bars... they look great and i can defiently feel the difference and my rs is stock... but i wouldn't pay the kind of money i did... i bought them off ebay both for 83 bucks shipped.. it wuzn't worth it... they do look good tho

the idea of a strut bar is good and buying them cheap isn't going to help but i went overboard and now i'm paying the price... literally. i like them tho.....

 

[96'GSspyder]

billet aluminum isn't good for strut bars?

 

[PaulPDX]

Originally posted by 96'GSspyder
billet aluminum isn't good for strut bars?

What gave you that idea?

 

[96'GSspyder]

Originally posted by Morphius
Those look like overlays, but who knows.

You'd get much better response out of a steel or aluminum version. Personally, I'd go with steel.

 

[PaulPDX]

Makes no difference, as long as the bar isn't flexible, it will do the job.

Generally, steel can go through more stress cycles before failing than aluminium. Steel will bend before cracking or shearing... where as aluminum will just break. Now, that's just the properties of the two metals in general. Most aluminum alloys used for strut bars (like T6) is strong enough where you won't have to worry about it breaking because the strain it sees don't come anywhere near to pushing it to its limits.

 

[ACM]

Strut braces are NOT in compression, they're in tension.

Think about it. Think about the origin of the loads, and where the fulcrum is.

Charles

Originally posted by Morphius
Those look like overlays, but who knows.

Even if they were Carbon fiber, I'd never buy one. Carbon Fiber is weak in compression. This is what your strut bar is trying to combat, movement of the strut towers inboard. When that happens, you're putting the strut bar in compression. You'd get much better response out of a steel or aluminum version. Personally, I'd go with steel.

 

[Morphius]

Originally posted by ACM
Strut braces are NOT in compression, they're in tension.

Think about it. Think about the origin of the loads, and where the fulcrum is.

Charles

Hmm, interesting. Have you ever put one in? If you have, then you'd understand.


Do a force diagram. The horizontal force is STILL transferred laterally in the chassis. The fulcrum creates a moment..........

 

[jtmcinder]

Has Charles ever put one in? Good one. Very funny.

Of course the force is across the car. And it all happens to be tension. The only thing that would cause compression in a STB is if you installed it with the wheels off the ground, which would be rather silly.

- Jtoby

 

[Morphius]

Originally posted by jtmcinder
Of course the force is across the car. And it all happens to be tension. The only thing that would cause compression in a STB is if you installed it with the wheels off the ground, which would be rather silly.

Stop and think about that statement very carefully. When you load the supsension.......... which direction is the bar being loaded? I think you just answered that.

 

[ACM]

Morphius:
Under cornering, the source of the load is at the tyre contact with the road. This load tries to push the tyre underneath the car, thus pushing against the wheel which in turn exerts a compressive force on the lower lateral arm. The outboard balljoint on this arm is the fulcrum, correct ?

Therefore, all forces above this point must be opposite, thus the upper arm/upper strut mount/upper anything-you-care-to-mention must be pulling outward, away from the centreline of the vehicle, and that force would typically be referred to as tension.


Enough already, get yourself a piece of paper and a pencil and draw it out ! This one is not rocket science.

Charles

 

[PaulPDX]

The force is tension. The only time it could be in compression is the front of the car is up in the air and then slammed down into the ground with both tires landing at the same time with equal force and the frame flexes or bends along its longitudinal axis.

Put pride and stubborness aside and think about it in simplified terms. Turning a corner hard, the outside strut tower flexing up... while the inside tower flexes down. The distance between the towers is increasing... pulling apart. That's tension.

 

[Morphius]

Originally posted by jtmcinder
.....if you installed it with the wheels off the ground, which would be rather silly.

Please explain that. And before you throw sarcasm in this, questioning my knowledge of suspension, take take this in mind. I have designed and built a suspension system from the ground up. It happened to be an indy car style (pullrod-SLA). And I've autocrossed that particular car and my DSM. I don't know everything, but I do have a good, wide knowledge base. At the same time, I'm always open to learn more.

With the wheels in the air, the car is statically unloaded. And the chassis, at that point, is in it's designed state. So we'll say that the strut towers are where they should be, and the resulting location and geometry of the suspension mounting points is correct. I don't know about your DSM (maybe mines very beat), but the difference in the strut location unloaded/loaded is around 3mm.

So, why would you load the suspension and base your adjustments off a strut tower that has now moved?

 

[Morphius]

Originally posted by ACM
Morphius:
Under cornering, the source of the load is at the tyre contact with the road. This load tries to push the tyre underneath the car, thus pushing against the wheel which in turn exerts a compressive force on the lower lateral arm.

Agreed.

Originally posted by ACM
The outboard balljoint on this arm is the fulcrum, correct ?

Depends on where you are looking at the resultant forces. The fulcrum can also be the LCA inboard mount.

Originally posted by ACM
Therefore, all forces above this point must be opposite, thus the upper arm/upper strut mount/upper anything-you-care-to-mention must be pulling outward, away from the centreline of the vehicle, and that force would typically be referred to as tension.

I will agree there can or is a breakover point at which it goes into tension.

 

[Morphius]

Originally posted by PaulPDX
The force is tension. The only time it could be in compression is the front of the car is up in the air and then slammed down into the ground with both tires landing at the same time with equal force and the frame flexes or bends along its longitudinal axis.

The brace will oscillate in compression until it reaches a breakover point in hard cornering. Where the resultant bending moments due to cornering are greater than those caused by normal forces due the weight of the vehicle.

 

[jtmcinder]

Originally posted by Morphius
Please explain that.

When the wheels are off the ground, the STB is in tension (although very little), because the tops of the suspension are, effectively, falling outward. If you installed your STB under these condition, you'd be deleting some negative camber (again, very little, but why lose any?). Therefore, you install the STB with the wheels on the ground. If you have an elephant handy to sit on your front bumper while tightening the bolts, I'd say go for it.

The same goes for a RRE lower front stress bar. Tighten the bolts with the car on the wheels.

- Jtoby

ps. with regard to your pedigree, keep the following in mind: the people who designed the Pontiac Aztec were professional car designers; also, I should probably warn you that I have a tendency to respond poorly to arguments from authority, while I have a tendency to respond very well to clear and logical posts, regardless of who wrote them -- heck, I've even agreed with igs once or twice

 

[Morphius]

Originally posted by jtmcinder
When the wheels are off the ground, the STB is in tension (although very little), because the tops of the suspension are, effectively, falling outward.

If very little tension, then when you set the car on the ground (or load it), it's not in compression?

Originally posted by jtmcinder
tops of the suspension are, effectively, falling outward.

And why is this the case? Where do you think the static designed point of the strut towers resides?

 

[jtmcinder]

I've never heard the term "static designed point" (nor can I find it in any of my texts), so I can't comment on that directly. But if you want to know which front suspension mounting point on a DSM has more strength - the top or the bottom - that's easy: the bottom (even without a RRE lower bar). Not that either are rock hard, of course. This is why, when cornering hard, the top ends of the outside suspension are moving outward. The force on the tire is at - ready for this? - ground level. The lower later control arm is the fulcrum. The upper A-arm is being pried outward. It's really that simple. And this is why the STB is in tension.

Send me a front STB for a 2G that has been cut in half, with 7/8" deleted from the center, with both of the cut ends tapped for a 10-24 bolt. I'd be happy to use one of my two-way force tranducers to give you specific values of tension (and compression, if I'm wrong) from the best corner that my car can produce. (I'll even pay to ship the pieces back to you.) Otherwise, I'm done with this topic.

- Jtoby

 

[MNGSX]

It is also why a neuspeed bar like what I run is better than a STB...

It's not really a STB but a bar connecting the rear bolt for the driver side upper arm to the rear bolt for the passenger side upper arm.. On a 2g the strut tower has nothing to do with the alignment of the suspension during cornering. It just mounts a shocks top and gives the spring something to push off of.. On a 1g or any other mac-strut car tying the ST's together is the right thing to do but on any multilink bracing the chasis at the upper link mounting point is a good idea.

Actually I'm thinking of making a bar to connect the front two upper arm bolts together and brace it to the rear bar. It would look like a H-bar...

 

[ACM]

Unfortunately I've seen the 2G Neuspeed bar - I sent it back with a note asking if they would send me some of the drugs their engineer was on at the time.

The one shown in the adverts is a good idea, picking up on the 4 eyebols - this addresses the torque generated around the pickups, as opposed to simply the tension as the towers try to spread.

Unfortunately that's not what Neuspeed built for a 2G - instead they built what can best be described as a large unused staple with tabs welded on each end.

Place one end on the floorand stand on it; hook index finger under top and tug - see that flex ? This STB has succeeded in being worse than useless - it provides zero structural enhancement and also adds weight high up in the front.

About as useful as a lead sheet sunroof.

Charles

P.S. This has become the silliest thread I've read here.

 

[jtmcinder]

Originally posted by ACM
P.S. This has become the silliest thread I've read here.

You need to read more, then. But I'll admit that it's in the top ten.

- Jtoby