Are strut/shock tower braces in compression or bending?

[tazio]

I'm having trouble visualizing the load paths, for whatever reason. Thanks!

[NoHaveMSG]

They work to resist lateral compression but due to packaging get some force in other planes as well.

Or something like that

[Spuds]

The primary force is compression/tension, but actually depends on the design of the bar. Hinged bars like Cusco will keep the strut towers equidistant from each other, but they can still twist about the hinge axis "freely" where a solid bar would resist that a bit.

I think in a turn you'd want both because as one side is loaded the other becomes unloaded and the front twists. But that might put more stress on the tower itself. I don't have any strut tower bars though.

[Ultramaroon]

Originally Posted by Spuds

I don't have any strut tower bars though.

Because you know better.

OP, in principle, the strut tower bar is a truss, plain and simple. It's there strictly to resist compression and tension between the joints.

Now, the harsh truth. The reason you never see a bent truss is because, just like putting a little dent in a beer can makes it super easy to crush, a bent truss buckles.

Take it the next step and consider already how little the strut towers flex in and out relative to each other. It's on the order of a few thousandths of an inch. I read a study here years ago that confirmed my suspicions.

(edit) @WildCard600 set me straight. It's ALL sad snake oil.

[wrong]For anyone emotionally attached to installing one, at least get the only one that means business. The grimmspeed bar is pure function. Anything bent, or with hinges is just sad snake oil.[/wrong]

[WildCard600]

Doesn't the grimmspeed mount to the flimsy little metal piece that is just spot welded to the tower though? I doubt it's effectiveness when it mounts to a piece that flexes so much it ends up breaking.


https://www.ft86club.com/forums/showthread.php?t=105791

[Ultramaroon]

Not looking at the whole picture. The spot welds fix together items for ease of continued downstream assembly. OP in your referenced thread let the nuts come loose. The real work is done by the weld studs clamping everything together.

With harsh service comes the responsibility of added vigilance and maintenance.

[WildCard600]

Originally Posted by Ultramaroon

Not looking at the whole picture. The spot welds fix together items for ease of continued downstream assembly. OP in your referenced thread let the nuts come loose. The real work is done by the weld studs clamping everything together.

With harsh service comes the responsibility of added vigilance and maintenance.

Maybe my eyes are going but I don't see any reference in that thread about loose bolts. Guess the others who posted the same issue also had these unmentioned loose bolts?

The mount is thin sheet metal you can deflect by just pulling up on the stock V bars that are already there by hand. I'm dubious it does anything.

[Ultramaroon]

Originally Posted by WildCard600

Maybe my eyes are going but I don't see any reference in that thread about loose bolts. Guess the others who posted the same issue also had these unmentioned loose bolts?

The mount is thin sheet metal you can deflect by just pulling up on the stock V bars that are already there by hand. I'm dubious it does anything.

Popped the hood scratching my head. Boy, was I wrong! All these years I've glanced and just mentally combined the bars with the top hat mounts. Those don't do shit. Now I'm just super disappointed.

I missed the whole picture.

[glhs386]

I think the Carbing design is pretty close to optimal. Bolts directly to the strut mounts, reinforces the V-brace brackets and is solid with no hinges. Also interestingly, I noticed that it doesn't naturally sit flush with the strut towers, so when you tighten the nuts it actually bends the bar slightly which seems to add a pre-load of sorts. Feels pretty damn solid overall. I know, I know, placebo.

[KillerBMotorsport]

Originally Posted by glhs386

Feels pretty damn solid overall. I know, I know, placebo.

Nothing wrong with that. If it puts a smile on your face, then it's working

[Ohio Enthusiast]

Originally Posted by glhs386

I think the Carbing design is pretty close to optimal. Bolts directly to the strut mounts, reinforces the V-brace brackets and is solid with no hinges.

And it comes pre-buckled! I'm not a mechanical engineer, but bent braces always feel like snake-oil to me. At least throw some gussets on the bends...

[glhs386]

Originally Posted by Ohio Enthusiast

And it comes pre-buckled! I'm not a mechanical engineer, but bent braces always feel like snake-oil to me. At least throw some gussets on the bends...

Wait until you find out they make roll cages out of pre-buckled bent tubes.

That's a joke, but I don't think your beer can analogy holds up. A tubular arch might not be quite as strong in compression as a straight one, but it can be strong enough for a particular application. As you said yourself, there's not a huge load going through these. Has anyone ever seen a buckled strut tower brace?

[Ultramaroon]

Originally Posted by glhs386

Wait until you find out they make roll cages out of pre-buckled bent tubes.

That's a joke, but I don't think your beer can analogy holds up. A tubular arch might not be quite as strong in compression as a straight one, but it can be strong enough for a particular application. As you said yourself, there's not a huge load going through these. Has anyone ever seen a buckled strut tower brace?

This is a joke. Hard pass.






I wouldn't sneeze at something like this.







First time I've even browsed for what's out there. Yikes!


And I feel pretty bad about having plugged the grimmspeed bar a few times. I should search for my other posts and edit them.

[NoHaveMSG]

Originally Posted by Ultramaroon

First time I've even browsed for what's out there. Yikes!


And I feel pretty bad about having plugged the grimmspeed bar a few times. I should search for my other posts and edit them.

I thought they were just fancy oil accumulator brackets


As much as I bash strut braces at least Grimmspeed put out their test data on the product page and included this(slightly misleading) graph.