BRZ/FR-S Strut Tower Brace - Any Interest?

[Captain Snooze]

Originally Posted by GrimmSpeed

This is not far off from the 12ft-lbs recommended for those studs,

Ummm.... totally unscientific opinion coming up:
12 ft-ibs doesn't read like much to stop any tower flex.

[whitefrs]

we need those other 2 diagonal bars

[dhenson405]

Add me to the list! Red looking sick

[Brzzee]

Black bar to 75088 please.

[whitefrs]

@loogs get this

[zex]

Wow did not see this til now.. interested ! Put me down

[chanomatik]

Originally Posted by Captain Snooze

Ummm.... totally unscientific opinion coming up:
12 ft-ibs doesn't read like much to stop any tower flex.

That energy is spread out across the bar, yo. Dissipation and shiz, dawg. Transference and all dat, son. Nahmean?

[Captain Snooze]

Originally Posted by chanomatik

Nahmean?

No I don't because it is the bolts that are anchoring the bar. If the mounting isn't strong enough the strongest bar in the world would be useless.

[doggieboy09]

I want one RIGHT NOAW!

[HSC]

Originally Posted by Captain Snooze

No I don't because it is the bolts that are anchoring the bar. If the mounting isn't strong enough the strongest bar in the world would be useless.

Yea, I'm still trying to understand that too. Considering everyone discourages against strut bars with pivot points (Cusco) and says it needs to be rigid, yet its anchor points are only torqued to 12 ft lbs? Wouldnt the chasis flex that this bar is trying to prevent exert more than 12 ft lbs? Just trying to understand this bar's full benefit.

[mottor]

Originally Posted by HSC

Yea, I'm still trying to understand that too. Considering everyone discourages against strut bars with pivot points (Cusco) and says it needs to be rigid, yet its anchor points are only torqued to 12 ft lbs? Wouldnt the chasis flex that this bar is trying to prevent exert more than 12 ft lbs? Just trying to understand this bar's full benefit.

The thing is, you have to consider where the force is being applied to the bar. When the chassis flexes it will push the two mounting points toward each other, rather than up or down. Most of the stress is not on the nut securing the bar, but on the bolt itself. When the chassis flexes on one side, the bar will be pushing outward on both mounting points. The bar would have to cut the bolts in half to fail.

[HSC]

Originally Posted by mottor

The thing is, you have to consider where the force is being applied to the bar. When the chassis flexes it will push the two mounting points toward each other, rather than up or down. Most of the stress is not on the nut securing the bar, but on the bolt itself. When the chassis flexes on one side, the bar will be pushing outward on both mounting points. The bar would have to cut the bolts in half to fail.

Thanks for the explanation but just like how its forces applied are not perfectly vertical, they are not perfectly horizontal either. I see the bar being "twisted" as it tries to prevent chasis flex and have to believe some of that torque will be applied in a vertical direction that the 2 nuts/bolts will then have to undergo.

[GrimmSpeed]

I have a sneaking suspicion that Chase will have a longer answer for you when he's back in the office on Monday, but here's my quick $0.02 regarding the torque spec.

First of all, we've tested it pretty thoroughly, and haven't had a single issue. The second is that 12ftlb doesn't sound like much, but it all depends on the fastener. Bolting something together isn't about how tight the bolt is, necessarily, it's about the clamping load that the head of the bolt and the nut exert. The bolt stretches as you tighten it and that's what provides the force. Take head studs, for example. The same set of studs with different lube and the same torque applied will produce clamping loads that are likely much different. In that same manner, two different bolts with the same lube (or no lube) and the same torque will provide different clamping forces.

In an application like this, the bolts are not being used in shear. They're used to clear a clamping load. Your wheels are held to your car just the same way. You're applying a clamping force and it's the force/friction between your hub and wheel that are actually interfacing. None of your studs/lug bolts should be experiencing any sort of shearing force. Make sense?

Here's a good chart that shows how clamping force and the applied torque behave. You can see on the bottom that a larger bolt requires a much larger applied torque to provide the same clamping force. This is why it's so important to be careful with smaller fasteners!

http://www.spaenaur.com/pdf/sectionD/D48.pdf

Chase will be back on Monday with what will probably be a much simpler answer!

Matt Beenen
Engineering

[GrimmSpeed]

Originally Posted by whitefrs

we need those other 2 diagonal bars

Your stock bars are just fine!

Originally Posted by dhenson405

Add me to the list! Red looking sick

Done!

Originally Posted by Brzzee

Black bar to 75088 please.

Got you added!

Originally Posted by zex

Wow did not see this til now.. interested ! Put me down

Thanks for the support, got you added!

Originally Posted by chanomatik

That energy is spread out across the bar, yo. Dissipation and shiz, dawg. Transference and all dat, son. Nahmean?

Originally Posted by Captain Snooze

No I don't because it is the bolts that are anchoring the bar. If the mounting isn't strong enough the strongest bar in the world would be useless.

Originally Posted by doggieboy09

I want one RIGHT NOAW!

Got you on the list!

Originally Posted by HSC

Yea, I'm still trying to understand that too. Considering everyone discourages against strut bars with pivot points (Cusco) and says it needs to be rigid, yet its anchor points are only torqued to 12 ft lbs? Wouldnt the chasis flex that this bar is trying to prevent exert more than 12 ft lbs? Just trying to understand this bar's full benefit.

Originally Posted by mottor

The thing is, you have to consider where the force is being applied to the bar. When the chassis flexes it will push the two mounting points toward each other, rather than up or down. Most of the stress is not on the nut securing the bar, but on the bolt itself. When the chassis flexes on one side, the bar will be pushing outward on both mounting points. The bar would have to cut the bolts in half to fail.

Originally Posted by HSC

Thanks for the explanation but just like how its forces applied are not perfectly vertical, they are not perfectly horizontal either. I see the bar being "twisted" as it tries to prevent chasis flex and have to believe some of that torque will be applied in a vertical direction that the 2 nuts/bolts will then have to undergo.

So glad you guys are thinking critically about the parts that you buy! That's exactly how it should be! I gave you a quick explanation above as to why 12ftlb is plenty!

Matt Beenen
Engineering