turbojeff

iTrader: (30)

The problem with all these non-stock braces is that they don't have the pre-load capability that the stock R1 brace has.

All other braces will flex more than the pre-loaded stock brace before taking a load. In the end the deflection of the body is what you are trying to stop.

Deflection of the bar is determined in a long member by the following equation. The brace is loaded purely in tension/compression. It is really only functional in tension.

D=P*L/A*E IIRC. D=deflection, P= load, L=length, A=cross sectional area, E= modulus of elasticity. The L is fixed, P depends on deflection of the chassis. The higher the E the more the P for the same D.

In the end it doesn't really matter one way or another for almost everyone here. The stock R1 brace is better than all other strut braces between the struts only IMHO.

FDNewbie

iTrader: (10)

LOL. Not that I got it all, but yea...I'm with him. Oh, and I also think the OEM ones look the nicest too. Very classy.

Jeff, I know this is a newb question, but how are the stock strut bars preloaded? Are you referring to the ability to lengthen or shorten them via that bolt on the side?

fallenengel

youngs modulus for Ti: 116/GPa
Al: 70/Gpa

1.65 times as strong.

fallenengel

since we're on this topic, any difference between the D-shaped and Oval shaped cusco bars? as far as performance goes.

i heard the oval was slightly stiffer, is this true?

dgeesaman

iTrader: (7)

Young's modulus is a stiffness measurement. The titanium bar of equal dimensions will be 1.65x stiffer than an aluminum one.

Strength is a different measurement (Yield Strength is a practical limit) and isn't a factor in this discussion: I've never heard of breaking a strut tower bar like you would an axle or PPF.

But, as someone already mentioned, the aluminum is about 40% lower density, so if you increased the size of the aluminum bar you could make it equally rigid for about the same weight. But it appears that at 570g, they've managed some weight savings, but at a pretty high cost, IMO. You could save a whole lot more by removing the stereo, has that been done yet? I'm not saying it's a bad thing to buy, but I don't think anyone who already has a strut bar should go out and upgrade.

As far as stiffness and grade of materials, the stiffness and density are nearly constant for all varieties of aluminum alloy and titanium.

TurboJeff, how does one preload the R2 strut bar? Would installing the bar when the front of the car is held by the floor jack at the crossmember be enough? (Figuring the weight of the car would push in the shock towers and make for some preload)

Dave

spekdah

"Spotting"

weaklink

What a high tech discussion of such a low tech piece.

neit_jnf

iTrader: (17)

I'm also wondering how to preload an R1 bar... should it be preloaded in tension or compression?

Tim Benton

iTrader: (1)

Your saving 2 pounds over the corksport strut bar, not 1 but your right, take a dump before you drive and you almost saved the same 2 pounds.

Tim

dgeesaman

iTrader: (7)

FSM, page R-25. You should torque the adjustable link to 4.0 Inch-Lb. and and then tighten the locknut to 105 in-lb. That's not a whole lot of preload.

The R2 bars don't have the adjustable link, which is my question. Page R-25 of the 94 FSM just shows it being bolted in.

Dave

turbojeff

iTrader: (30)

The pre-load is minimal for sure but I mentioned the adjustable R1 bar since the discussion was getting sort of silly.

Strut bars are loaded in tension. A long slender beam won't work well in compression, think about pushing a rope.

dgeesaman

iTrader: (7)

That's surprising to me.

I wish I had a Howard Coleman-esque grasp of suspesion dynamics, but I thought a strut tower handled both tensile and compressive loads. By rigidly connecting the strut towers, engine cradle, and strut tower bar, it creates a rectangular box that is much more rigid than when the strut tower bar is absent.

It appears to me the bar is designed to be rigid in bending, compression, and tension while still fitting the space left under the hood. It's not a bridge pillar, for sure, and the compressive capacity is limited to the grip of the bolts in it, but it looks more than simply tensile.

Dave

turbojeff

iTrader: (30)

The R1 bar has a heim joint, no bending moments will transfer though it, strictly compression/tension. Others have a bolted joint with one bolt (end to bar joint), the bolt effectively limit any bending moments also.

The outside tire will do most of the work in cornering since it has the most weight on it, it produces a load that will pull the strut tower towards the outside of the car. The inside tire will produce an opposite load but with lower magnitude. This leaves the strut brace in tension.

Yes the strut tower does handle both tensile and compressive loads. The strut brace is really only going to work in tension.

Zero R

iTrader: (1)

We have had the Cusco Ti bars in the shop. For both a EVO and FD. They were unbelievably light but the actual ends seemed very flimsy sheet metal thin

adam c

iTrader: (2)

Dave,

I believe the torque specs just tell you how much to tighten the nut. They don't have anything to do with preloading.

It's funny that this is such an in-depth discussion. FWIW, most any strut bar will do the same thing. Buy one that you like the looks of, and you will have made a good decision ............ unless you pay over $200

TT_Rex_7

That's because your a 'Cheap bastard'. (From above your avatar)

-Alex

the_glass_man

iTrader: (2)

Says the man with the carbon fiber driveshaft!

Tim Benton

iTrader: (1)

aw damn, busted. BTW I saved 3 pounds with the 900 dollar CF drive shaft so it was more than 2 pounds!

Tim

FDNewbie

iTrader: (10)

To each his own, but you know Adam, I think the stocker looks by far the best.

dgeesaman

iTrader: (7)

And it's a rotating component. Flywheel effect, baby!!