Aluminum PHB vs. Steel PHB

[Tob]

You are taking things way too personally. If you can't handle praise then so be it. There's no snarkiness intended.

I stand behind everything I said. And you have no idea of my 'knowledge' so maybe come down off your high horse and accept the fact that there are others around the world that can comprehend simple 'engineering' concepts.

Interesting facts, not sure why you felt the need to state them. As to your last 'fact'...

Friction at one or both bushings is capable of geometrically deforming the bar.

And I'm capable of flying. How's that for a general statement? Did anyone say that friction couldn't? Care to be more specific so that we can address the subject of an aluminum panhard versus a steel one?

This deformation WILL change the loading scenario drastically when under compression in a way that seriously weakens the bar.

Another generic statement. Care to provide specifics in the context of an S197 chassis including suspension setup for a given example?

If you still refuse to accept this fact, I'm not sure what to tell you.

Do you know what a straw man is?

Lars, if you want to discuss materials 101, that's great. If you'd like to engage into deeper conversation involving vehicle dynamics (with respect to the panhard bar in an S197 chassis) and how steel/aluminum is affected by load under certain circumstances (varying degrees of bind at a given pivot point or bushing) then I'm, all for it.

In the meantime, have you found that example of aluminum panhard bar failure yet?

 

[CCS86]

That's always a grey area on the internet... I appreciate the compliment sir.

You are not capable of flying, but friction at a bushing does create a bending moment throughout the bar.

My point is that in ideal conditions (a simply supported member under tension or compression), I would pick aluminum every time. But when a 30 lb-ft frictional moment at a bushing can multiply stress in the bar by 8 times; and when every vibration in the road excites and stress cycles the bar; steel provides a higher factor of safety when working with typical packaging constraints.

I haven't searched for an aluminum panhard bar failure, and don't plan to. The facts don't change either way. The vast majority of panhard bars out there are steel, and not everybody posts stuff like that. You are smart enough to know that there is no significance to being able or failing to find a post about a failed aluminum bar. Actually, the failed steel bar you posted only strengthens my case, since under the same conditions that caused that failure, an aluminum bar would have failed sooner.

I don't think we have to get into the vehicle dynamics of an S197 chassis to come to these conclusions. Ideally, the panhard is a 2-force member and is loaded in pure compression / tension. We both acknowledge that bushings are capable of generating a frictional torque, especially with poly bushings at both ends. Using only that information we can simulate both scenarios.

 

[Tob]

Your point about 'ideal' conditions is well taken. I feel much the same about certain aluminum LCA design's, specifically Granatelli's early attempts for use on a Fox chassis.

Regarding the steel bar failure I posted on earlier, the conditions of which are rather murky. My point was simply a counter to any assumption that the steel production units are without failure. They aren't.

Now, if we can revisit my earlier comments regarding bushing choice in concert with bar material - specifically that of the use of a rod end in conjunction with an aluminum bar. Since any change in bar is probably being done to enhance performance, using an inferior bushing such as poly, can be a bit counterproductive - especially with respect to bind. A properly designed aluminum panhard bar that utilizes a heim at each end goes a long way to minimizing unwanted additional stresses imparted by typical aftermarket poly bushings, at least to the bar itself anyway.

 

[Ry_Trapp0]

lets not forget that the whole key to this entire argument is "if a bushing seized". use rod ends as Tob mentioned, or perform regular maintenance on your poly equipped aluminum PHB and that won't happen. problem solved, disaster averted, the world is once again a safe place.

and LOL @ grantelli

 

[CCS86]

Your point about 'ideal' conditions is well taken. I feel much the same about certain aluminum LCA design's, specifically Granatelli's early attempts for use on a Fox chassis.

Regarding the steel bar failure I posted on earlier, the conditions of which are rather murky. My point was simply a counter to any assumption that the steel production units are without failure. They aren't.

Now, if we can revisit my earlier comments regarding bushing choice in concert with bar material - specifically that of the use of a rod end in conjunction with an aluminum bar. Since any change in bar is probably being done to enhance performance, using an inferior bushing such as poly, can be a bit counterproductive - especially with respect to bind. A properly designed aluminum panhard bar that utilizes a heim at each end goes a long way to minimizing unwanted additional stresses imparted by typical aftermarket poly bushings, at least to the bar itself anyway.

Oh my god! You don't need a degree to see how terrible a design that LCA is! :kaboom:

Definitely, a double heim aluminum PHB of the proper alloy and size would be totally fine.

 

[CCS86]

lets not forget that the whole key to this entire argument is "if a bushing seized". use rod ends as Tob mentioned, or perform regular maintenance on your poly equipped aluminum PHB and that won't happen. problem solved, disaster averted, the world is once again a safe place.

and LOL @ grantelli

Well, not quite. The term "seized" implies that the bushing is completely frozen/locked. That would be almost impossible. "Bind" refers to deflection induced friction, and has a wide range of magnitude.