Spindle lessons

Robert Daniel · Joined: 26 Oct 2008 Posts: 119

I'm a little confused. Since all steel has essentially the same modulus, spindles made of 1018, 4130, 8620, would all behave the same.

Gary Lawson · Joined: 21 Aug 2001 Posts: 542

The big 25mm spindles must be hollow given they are noticeably lighter than a 17mm spindle

kyle luttrell · Posted: Mon Feb 25, 2013 10:38 am Post subject:

Yes those maybe hollow but they are made of a better grade steel. The hollow them to lighten them up.

No a hollow axle isn't stronger then a solid axle if both are made of same material lol [/list]
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mike clements · Posted: Mon Feb 25, 2013 10:54 am Post subject:

Robert, Those materials you listed act completely different in the real world.
Kyle, I know better. I, and many people before me, have actually tested this theory. I learned this first about 33 years ago when my new Emmick kart came with a solid 1.250" axle. Within a month, they sent me a new hollow axle that was stiffer. The materials were the same according to Gary Emmick. It had a .250" wall thickness. The .188" wall axles flexed too much.
Don't get me wrong. I am not arguing with you. This is common engineering knowledge.
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kyle luttrell · Posted: Mon Feb 25, 2013 11:07 am Post subject:

Hey,
Well ill tell you want ill do..

Ill get two solid 1'x1" 4130 chromoly and hollow one out and do a test...

Are you a betting man?

500$ to you if the solid one bends before the hollow one ??
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Ionic Edge
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mike clements · Posted: Mon Feb 25, 2013 11:41 am Post subject:

How large is the I.D. of the hole ? Remember, we discussed this already.
Here's what you do. You go ahead with your game and I'll go with what I know works. Good Luck to you.
MC
"Began Kart racing in 1959"
"12 years working for GM Engineering staff"
Born into a racing family.
4 National Championships as a driver.
70+ National Championships as an engine builder.
Published author
Holder of 3 U.S. Patents on internal combustion engine design.
World Land Speed Record holder for 4 cycle karts.

You ?
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Gary Lawson · Joined: 21 Aug 2001 Posts: 542

I was just stating what may not be obvious to some. No one needs to start puffing chests out. Winter is almost over so we can get back to letting results speak again. The past is over.

kyle luttrell · Posted: Mon Feb 25, 2013 4:58 pm Post subject:

Do you think I just went out and spent 1000's if dollars without testing?

Lol right Smile

lol

I don't gamble lol

You are deffantly respected in the go kart industry.

I'm also a ff... A wise chief once told me if you have to tap on your badge/accomplishments then it means nothing.

I don't claim to know it all or have done it all but ill sure die hard trying!
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Michael Purnell · Joined: 27 Sep 2006 Posts: 29

mike clements · Posted: Wed Feb 27, 2013 11:32 am Post subject:

oops

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mike clements · Posted: Wed Feb 27, 2013 11:49 am Post subject:

I just noticed that Margay is building a new offset kart for dirt oval racing. Their front spindle arrangement is quite nice and innovative. They also advertise that the material they are using is 8620, just like I did when building mine.
What are you using ?

The only reason I posted anything about past accomplishments is because by far the readers on this site are 2 cycle racers and mostly TaG racers. They are much younger than myself and therefore have no idea as to who Mike Clements is. I am not bragging. When I get as many National wins as Lynn Haddock, Kyle Adkins or Ronnie Emmick, maybe Then I'll brag.

While working for GM Engineering Staff, we used a lot of strain gauges to test various materials and sizes. On sway bars and torsion bars, there is no doubt at all that the hollow tube is stronger and resists twisting more than the solid. NASCAR sway bars and roll bars are tubular as are in just about any form of racing. It's not a weight thing either. If the sanctioning body thought solid was stronger, they would mandate solid.

We did the exact tests you may be thinking of by placing solid bars of steel, various alloys, in a hyd press with a pressure gauge. Apply pressure to them and measure the deflection at the center of the rod. Let's say a 2" diameter for example. Then try a 2" diameter tube of the same alloy. In every case, the tube resisted the pressure better than the solid bar.

Again, I am not going to argue with anyone. My list of accomplishments is my proof. This worked for me and General Motors and NASCAR and Indy Car and Formula 1 and SCCA, etc. You do what works for you and I'll do what works for me.
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joseph hollinger · Posted: Wed Feb 27, 2013 12:03 pm Post subject:

You can find an online calculator for tubing deflection here: http://www.calculatoredge.com/civil%20engg%20calculator/beam.htm

I entered the data for two tubes. Both 1" OD and 100" long. Both subject to a 100 pound load. Both steel. One solid, one hollow with a .1" wall thickness. As you can see, the hollow tube bends a lot more than the solid tube.

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mike clements · Posted: Wed Feb 27, 2013 12:16 pm Post subject:

Joe, Just for fun, please enter 1.250" O.D. with a .250" wall thickness.
Then compare that to a wall thickness of .188".
These are common numbers for American 1 1/4" axles. Length is 42" for spring racing.

Also, I noticed 70,000 more PSI on the tube as compared to the stress on the solid bar ?
thank you, Mike
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joseph hollinger · Posted: Wed Feb 27, 2013 12:27 pm Post subject:

Everything else being equal, the tube with the .188 wall bends about .1 more for a 100 pound load.

The field marked "bending stress" is value calculated to reflect the difference in tension at the top of the tube compared to compression at the bottom of the tube. The more a tube is deflected, the greater than value should be.
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bob prinzo · Posted: Wed Feb 27, 2013 11:27 pm Post subject:

id like to know which one of you guys argueing with mike are actual educated engineers.
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