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

[GrimmSpeed]

Originally Posted by chanomatik

@GrimmSpeed: I've only recently become acquainted with you guys with the hood strut purchase. What is your typical turnaround time from idea to conception for your products? Didn't the hood struts only take barely 9 months? I forget. Anyways, I've seen you guys around for a while, but never paid attention until the struts. Now I'm a believer and looking forward to this next product!

I hesitate to make any promises here, but if things go as planned (and it warns up here for some testing), we'd love to be showing you guys production parts in 8wks or so. We move quickly, but never rush!

Originally Posted by Gunman

Are you guys SEMA members, at the manufacturer level? Tech Transfer would get you the CAD data, and many times you can glean information from that, as to how/why things are done, ie bars too short/long being designed for preload, etc. I don't believe Subaru participates, but Scion does.

http://www.sema.org/tech-transfer

I never dealt with data from Scion, but GM is great to work with via this program.

We do participate in Tech Transfer.

Matt
Engineering

[sierra]

Originally Posted by GrimmSpeed

Bummer!

One thing to remember is that in the manufacturing world, the cost difference is not simply in material cost. Most people don't mind an extra half pound to save a good amount of money. Because of that, a smaller production run of aluminum parts is substantially more expensive and would have quite easily doubled the cost of the kit.

For what it's worth, in this application, the weight difference between two comparably rigid bars (one aluminum, one steel) is quite subtle. Think on the scale of two tenths of a gallon of gasoline.

That said, we appreciate the valuable and honest feedback! The design isn't complete and it's not too late to make changes. Chase and I will discus materials more closely in the morning!

Matt
Engineering

You are good guys!
How about costing it in alloy and steel at an early stage so you don't need to have 2 sets of design parameters, to judge the response?
The difference in weight might not be large but it's there for the life of the car in fuel consumption, acceleration, braking and handling.
Surely it's not twice the price?

For another car it might not be important but this one is light and nimble and deserves to be given true fuction over form, not a compromise to save a few dollars in the short term.

A great option in alloy would be polished, black or a combo.
I particularly liked the machine finish on the strut mountings in the pics I posted. My choice would be that with a black tube.

[GrimmSpeed]

Originally Posted by sierra

You are good guys!
How about costing it in alloy and steel at an early stage so you don't need to have 2 sets of design parameters, to judge the response?
The difference in weight might not be large but it's there for the life of the car in fuel consumption, acceleration, braking and handling.
Surely it's not twice the price?

For another car it might not be important but this one is light and nimble and deserves to be given true fuction over form, not a compromise to save a few dollars in the short term.

A great option in alloy would be polished, black or a combo.
I particularly liked the machine finish on the strut mountings in the pics I posted. My choice would be that with a black tube.

The reasons for selecting steel over aluminum aren't simply regarding cost. The justification for steel is that it can function as well as aluminum, in this application, at a substantially lower cost. As long as we're talking function vs. form, here's some food for thought.

In the design of a bar like this, we're most concerned with stiffness, not strength, since a bar that's stiff enough for our needs will certainly be strong enough. When we talk about material selection with stiffness as a primary goal, we compare the modulus of elasticity, not the yield strength. The modulus of aluminum is around 10 million psi, while steel is around 30 million psi. What this means, roughly, is that for a standard structural shape (a round tube, in this case), for the same limit of bending with the same load, the aluminum tube will require a wall thickness that's around 3 times as great as the steel tube. Now, steel is roughly 3 times heavier than aluminum. So, you can see that comparably stiff aluminum and steel tubes are actually, like I mentioned before, very similar in weight. We're talking did you finish your glass of orange juice this morning or not weight.

Of course, this is pretty general, but you get the idea. You'll see some finite element analysis that we've done later on and that might help make things more clear.

Matt
Engineering

[sierra]

Originally Posted by GrimmSpeed

So, you can see that comparably stiff aluminum and steel tubes are actually, like I mentioned before, very similar in weight.

Matt
Engineering

I just googled that and can only wonder why steel hasn't been used in any aircraft structures to save money? Perhaps fear of galvanic corrosion stops it being mixed with the the alloy?

Maybe i'm just yearning after some to play with again? So much sexier than steel.

How about using high tensile steel? It's up to six times stronger than conventional steel.

http://www.thetruthaboutcars.com/201...ght-and-money/

[mottor]

Originally Posted by sierra

A great option in alloy would be polished, black or a combo.
I particularly liked the machine finish on the strut mountings in the pics I posted. My choice would be that with a black tube.

No offense meant, but if you like the one by Password JDM so much and cost is a non issue, why not just buy their bar instead of influencing Grimmspeed to make one just like it? I like the fact that Grimmspeed is doing things differently to cut cost without sacrificing structural integrity. It seems to me that they're offering the most back to basics, function intensive product possible. Again, no offense intended just thought it would make more sense.
:happy0180:

[GrimmSpeed]

Originally Posted by sierra

I just googled that and can only wonder why steel hasn't been used in any aircraft structures to save money? Perhaps fear of galvanic corrosion stops it being mixed with the the alloy?

Maybe i'm just yearning after some to play with again? So much sexier than steel.

How about using high tensile steel? It's up to six times stronger than conventional steel.

http://www.thetruthaboutcars.com/201...ght-and-money/

Sounds like $150 might not buy you the kind of sexy that you want.

Seriously though, more exotic alloys would incur a significant cost increase, at again, little to no performance gain. Aircraft structures often do use steel, but only in places where manufacturing methods or cost prohibit other materials. Having worked in the defense/aerospace industry, I can tell you that those folks work with a budget that normal people like us can't even comprehend.

You should look up a photo of 787 wing deflection testing.

Matt
Engineering

[Spartan65]

I've read the thread and a couple of questions come to mind.

1. Is this supposed to be installed while the car is of the ground?
2. What determined the actual width of the bar?
3. Is it possible to show the metal stress points?

[Slartibartfast]

Just found this thread. How did I miss it?

First off... every piece I have purchased from Grimmspeed has been top notch. The hood struts are FAR superior to any others I have seen in action. Also the Master Cylinder Brace really surprised me, I DO notice a difference under hard braking. I did some Pre and Post-install testing. Great feel at the limit. (Not a placebo effect)

So... I trust your engineering methods. I have NO engineering background, so I won't comment on the design.

So what can I add for input...

I think we all have the same goals here. Function over form, allowance for use in different race series, and the lowest weight that is cost effective. I am a weight freak, and wouldn't mind spending an extra $10-20 for it to weight a little less.

I would like to see one tower to tower bar, with an option for matching tower to firewall braces. Can this be done at low cost, and low weight?

Esthetics. Looks shouldn't matter right. But, all of you know that they kinda do. My Grimmspeed oil cap and battery brace look awesome. The red cap on the MCB looks kinda cool too. But, I didn't put the stickers on the hood struts because I have nothing gold under my hood. I really like the metal sticker concept. I think it's a great idea, but I would really, REALLY like it to be consistent across your product line. Red and silver, optional placement, metal sticker, on a flat black bar for me please.

If a group buy comes about... you can add me without question.

:happy0180:

[sierra]

Originally Posted by mottor

No offense meant, but if you like the one by Password JDM so much and cost is a non issue, why not just buy their bar instead of influencing Grimmspeed to make one just like it? I like the fact that Grimmspeed is doing things differently to cut cost without sacrificing structural integrity. It seems to me that they're offering the most back to basics, function intensive product possible. Again, no offense intended just thought it would make more sense.
:happy0180:

I didn't say that cost was a non issue[I think?] rather that I didn't mind paying more for a lighter functional product and a bit more to make it look good.
I posted the pic of the JDM bars because I thought it was interesting and Grimmspeed have asked for feedback. If they could make something like that for $250 instead of $450? I would buy it.

[s2d4]

Originally Posted by sierra

I didn't say that cost was a non issue[I think?] rather that I didn't mind paying more for a lighter functional product and a bit more to make it look good.
I posted the pic of the JDM bars because I thought it was interesting and Grimmspeed have asked for feedback. If they could make something like that for $250 instead of $450? I would buy it.

1. Negligent in weight as explained.
2. Not extra 100 dollars just for looks.

You actually just want the password JDM item to be cheaper.
I don't think that is what grimspeed is about.

[GrimmSpeed]

Originally Posted by Slartibartfast

Just found this thread. How did I miss it?

First off... every piece I have purchased from Grimmspeed has been top notch. The hood struts are FAR superior to any others I have seen in action. Also the Master Cylinder Brace really surprised me, I DO notice a difference under hard braking. I did some Pre and Post-install testing. Great feel at the limit. (Not a placebo effect)

So... I trust your engineering methods. I have NO engineering background, so I won't comment on the design.

So what can I add for input...

I think we all have the same goals here. Function over form, allowance for use in different race series, and the lowest weight that is cost effective. I am a weight freak, and wouldn't mind spending an extra $10-20 for it to weight a little less.

I would like to see one tower to tower bar, with an option for matching tower to firewall braces. Can this be done at low cost, and low weight?

Esthetics. Looks shouldn't matter right. But, all of you know that they kinda do. My Grimmspeed oil cap and battery brace look awesome. The red cap on the MCB looks kinda cool too. But, I didn't put the stickers on the hood struts because I have nothing gold under my hood. I really like the metal sticker concept. I think it's a great idea, but I would really, REALLY like it to be consistent across your product line. Red and silver, optional placement, metal sticker, on a flat black bar for me please.

If a group buy comes about... you can add me without question.

:happy0180:

Thanks for the detailed input! We (seriously) take each and every bit of this stuff into account both during design and during team reviews where we talk about the project, it's status and the path forward. Like Justin said, you guys rock!

Originally Posted by sierra

I didn't say that cost was a non issue[I think?] rather that I didn't mind paying more for a lighter functional product and a bit more to make it look good.
I posted the pic of the JDM bars because I thought it was interesting and Grimmspeed have asked for feedback. If they could make something like that for $250 instead of $450? I would buy it.

Don't get me wrong, we do our market research, but we also make decisions for ourselves; requirements that we hold ourselves to through the design process. In this case, those requirements don't align themselves with a design that is similar to the pwjdm parts. We want maximum performance at a reasonable cost. Based on our research and testing, I'm convinced that we can perform the same (or better) function as the pwjdm product for nearly $300 less. If you want the fancy 'features' of the pwjdm bars and you're willing to pay for it, you should buy the pwjdm bar. On this project, we're interested in actual function, not perceived function, and I don't think actual function needs to cost $450. Again, we absolutely appreciate the feedback though!

Originally Posted by s2d4

1. Negligent in weight as explained.
2. Not extra 100 dollars just for looks.

You actually just want the password JDM item to be cheaper.
I don't think that is what grimspeed is about.

:happy0180:

Matt
Engineering

[White64Goat]

Since at least one forum member and maybe more have snapped off the nut from one of those studs, what are those 2 studs made from? If you stick your finger up under the bracket you will feel that those 2 studs do not have a 6 sided bolt head, it's more like a stud glued to a dime (to try and explain it in common terms). I don't believe those 2 studs have much strength to them and while it looks like an aesthetically clean installation, I have serious concerns as to the strength of those 2 studs (plus they're attached to a small welded on bracket and not the strut studs).

[GrimmSpeed]

Originally Posted by White64Goat

Since at least one forum member and maybe more have snapped off the nut from one of those studs, what are those 2 studs made from? If you stick your finger up under the bracket you will feel that those 2 studs do not have a 6 sided bolt head, it's more like a stud glued to a dime (to try and explain it in common terms). I don't believe those 2 studs have much strength to them and while it looks like an aesthetically clean installation, I have serious concerns as to the strength of those 2 studs (plus they're attached to a small welded on bracket and not the strut studs).

I'll touch on this quick again: You kind of answered your own question, those studs don't have bolt heads because they are pressed in studs. That way it is easier to remove and install the triangulation bars, especially without specialty tools. The torque specification for those two studs is 14ftlbs, which is relatively low. With that said, it provides more than adequate clamping force on the triangulation bars, such that the bars do not end up slipping against the nut even under the loading the car sees during hard cornering. However, just because some members have broken the studs does not imply that they are weak, especially in shear, which is the type of loading that a strut bar would exhibit upon them. Especially since the strut bar we have prototyped has such a thicker flange, it greatly increases the bearing surface on the stud, which helps to minimize the shear force.

I want to say again that these studs were designed to handle the forces from the stock triangulation bars, and were definitely designed with a certain safety factor, and I can almost guarantee it's greater than 2. Unfortunately without knowing the grade of the studs I can not calculate the ultimate tensile strength, but I can rely on our own testing with our prototype. If nothing else, I'd like the note again that the engineers at TRD (who would have access to this information) have elected to using the same mounting points in their strut bar.

And to reiterate, the initial deflection data that we've shown is from our car, and is measuring deflection at the strut mounting studs with and without our prototype strut bar. To say that the "small welded bracket" is not influencing the struts directly is debunked right there. Even though the bracket is made out of sheetmetal it is important to keep in mind that it has a substantially higher equivalent strength over flat sheet metal due to its three dimensional shape.

We'll continue testing, but so far we're not concerned with the shear strength of the studs

Here's a few shots of a quick prototype from yesterday. What do you guys think about the brackets? What would you change?





Chase
Engineering

[mottor]

The previous prototype bracket had a solid support on the front side. Do you find that it is equally as strong with the cutout? Also, is there any benefit to be had by using this support on the face of the bracket instead of alongside it?