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JJ & A Axles


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16 minutes ago, trickedcarbine said:

Zilla & Claude, why is JJ&A drilling vs using tube...? It's more work,why bother with it, if they are making a weaker product?

 

By tube you mean solid or do you mean tubing like used in frames?

Reason jja does hollow axle is because mass. A solid axle would be stronger, but if they can make an axle lighter and it still work within the design parameters, why not?

Like I said before, most torsional strength comes from the OD of the bar. So drilling out the center might mean you lose a little percent of the strength, but also loose a lot more mass.

Shear stress is directly porpotional to cross sectional area. So the less area, the less force it can handle. 

In bending, the center does see a lot of the stress because it is the neutral axis. The farther you go out from this axis, the more strength you have.

 

It all comes down to mass. Keeping mass the same, a hollow design will be stronger. Keeping size the same, solid will be stronger.

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JT, c’mon this is BHQ we all know real world experience doesn’t matter. Google and some computer program even say so.

 

 

Sent from my iPhone using Tapatalk

 

Theory and real world always match. It match in this very case too, but for some reasons, that i really dont understand, you can't belive a mechanical engineer with 20 years of experience. 

I already provided a simulation, Nick explained it , torsion and shear formulas are known for century!! What else can we do??? It's not even debatable ffs!!! It's BASIC ENGINNERING, i can also provide formulas if you want. Then what, you will say those formulas arent true??

 

Same size/shape , solid is stronger.

Same weight, hollow is stronger.

 

Envoyé de mon SM-G935W8 en utilisant Tapatalk

 

 

 

 

 

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9 minutes ago, ClaudeMachining said:

Theory and real world always match. It match in this very case too, but for some reasons, that i really dont understand, you can't belive a mechanical engineer with 20 years of experience. 

I already provided a simulation, Nick explained it , torsion and shear formulas are known for century!! What else can we do??? It's not even debatable ffs!!! It's BASIC ENGINNERING, i can also provide formulas if you want. Then what, you will say those formulas arent true??

 

Same size/shape , solid is stronger.

Same weight, hollow is stronger.

 

Envoyé de mon SM-G935W8 en utilisant Tapatalk

 

 

 

 

 

I'm guessing it's because sometimes basic engineering doesn't always work in the real world. I see it all the time on prints. Looks great on paper..No fucking way it will work on the job.

Other than that, WGAF? Both are strong. I've had both. Currently run all gun drilled on all our bikes. Zero problems.

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Drilled is stronger than solid.

 

Pretty simple to understand.

 

Stupid simple. Also for the wanna be Google smart peeps stock axle size and material is not used on the 7075 gun drilled axles for drag racing. Guess what....the 7075 gun drilled axles are lighter than stock, stronger, and work in real world. Peeps need to look at design and application before posting shit that doesn’t pertain

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Same 12`` long, 2`` diameter tubes. One is solid and one is hollow. Same forces on them.

 
The solid weight 1674g and got a max stress of 7070psi.

 The hollow (.250`` wall) weight 732g.and got a max stress of  11000psi.

 

So no debate, the solid is stronger, the simulation is 100% accurate.

 

The fun part is lets check how big the hollow have to be, to be as strong as the solid and how i twill weight. That is engineering, that is the fun part.

I played with some config for about 5 min and here is the results :

With a hollow tube of 2.4`` Dia, you got the same strengh with 900g weight!!!

That’s why we say solid is always stronger for the same shape and size, but hollow have a better weight to strengh ratio.

I hope i twill clear any doubts about this subject. Theory must match real life and i gave you the example.

 

Short story: It take a 2.4`` hollow tube with .250 wall ( 900gr) to be as strong as a solid 2`` tube. (1675gr)

 

 

 


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