Dog Bone Torture Test Results

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Grumpy1822

Grumpy1822

Savage Owner
Messages
790
Location
Kenner, Louisiana
I locked each bone in the vice and increased torque until they snapped. All were locked into the vice by the end and twisted at the other end. All failed at the end being twisted.

Stock black 6.5l ft/lbs $10
HD chrome 8 ft/lbs $14
IRC 14 ft/lbs $23
GPM titanium started to twist at 19 ft/lbs. increased to 32 ft/lbs they didnt snap until they twisted all the way around almost two full reveloutions. $29

Thanks to those who sent me some test subjects. The stockers came in an envelope with no return add. Kiz? I would love to get my hands on some other types to test. New era, FLM the new 5.9's or any others you guys can find.

Just for kicks the stock lst2 shafts gave way at 11.5 ft/lbs.
 
Very good info. Thanks for the information. Please keep the post up to date with any others you test.

I am definitely interested in the GPM ones then if they hold up so much better. Maybe well worth the money over the stockers or the HD's.

+Rep
 
What a great idea. Thanks for thinking this up and sharing the results with all of us! :resp:
 
interesting info. Don't think anyone has ever tested a product the way You did. Even more interesting to see the bones weakness was by the way of twisting prior to snapping.

Gotta ask - You have any pics by chance?
 
A lot of mine deform before snapping and I often catch them before they snap. We need to work out a test to find the how resistant the pins are to wear. It would be nice if the had easily replaceable pins too like the phat bones for the baja.
 
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Here you go Brian. You can see in the pic how much the GPM twisted beffore snapping. The IRC also twisted some. The 2 HPI bones snapped almost instantly. Left to right GPM, IRC, HD, Black
jjuhyu.jpg
 
I almost forgot to mention Rob at IRC donated a pair of his bones for the test. Thanks Rob.
 
I put a socket 15mm (fits in the opposing corners) on it and twisted with a torque wrench. Got some centers today. Both black and HD broke at 10 ft/lbs. It seems they are identical tensil strength wise.
 
Different test. Bend test.
Results from the 90 deg bend test. All bones locked in a vice half way and bent down to 90deg with a notched plug in a socket with a torque wrench. All bent the full 90deg without snapping.

Black 11 ft/lbs
HD 11 ft/lbs
IRC 12.5 ft/lbs
GPM ti 17 ft/lbs

So the HPI bones have a higher bend tolorance than twist tolorance. The Titanium and IRC bones had a lower bend rate than twist. Interesting. These are the same bones that I twisted so maybe the ti bones were weakened from the first test. They were twisted almost two full reveloutions. I don't know if this sheds some light on the flexability or not.
 
lol just snapped the black ones, I accidently had them in the rear and the hd ones up front, my bad lol.
 
One thing. To bad you didn't test it in the drive cups. I'm sure a cup would fail before 2.5 twists on the torque wrench. When we test components for durability we don't put constant stress on it. we simulate a years worth of stress in about a month. could you do a machine with every day components that can add and release the stress on the bones? This way it will simulate the stress of driving. But very nice on the static force test on the bones. I'm very surprised that the titanium bones didn't snap outright.
john
 
grumpy1822 said:
Different test. Bend test.
So the HPI bones have a higher bend tolorance than twist tolorance. The Titanium and IRC bones had a lower bend rate than twist. Interesting. These are the same bones that I twisted so maybe the ti bones were weakened from the first test. They were twisted almost two full reveloutions. I don't know if this sheds some light on the flexability or not.
Click to expand...

Every time you work (bend) a metal, you actual harden it's structure, however this also makes it more brittle. The bias of these effects and and the 'speed' (amount of work done to cause said effect) will vary depending on the type of metal (it's original properties).

How this affects the test results:

The HPI bones required less "work' to snap them (rotationally). Since the shafts didn't twist before the ends snapped off, one could assume less fatigue has occurred in the shaft, it will remain almost as pliable (flexible) as it ever was

IRC and Ti bones shafts will have fatigued severely (most so the Ti) due to the amount of twist the shafts withstood before snapping in the rotational strength test. Hence they will have withstood less in the bend test. The Ti I would expect to bend to 90º and either return straight or give out after being held under load for a while.

Thus I feel that a new example of each would give a similar result for the HPI bones, and a similar result in terms of winning margin to the first test for IRC and Ti bones.
Really to make the second test fair on used bones they would have all needed to be bent the 2.5 revolutions or 30 ft/lbs the Ti withstood from the first test.

However, this is still an excellent insight, and thanks for going to all the effort! It shows the IRC are probably going to be the best value for everyone, at £13ish for a set of four. It would be interesting to know if the drivetrain can generate enough torque to break them (assuming it can generate enough to snap stockers).
It was neglected that the Ti bones only come in pairs at £15 a pop (£30 a full set), but they are a good material for this application, being also very light. I would like to know if they begin to twist at a lower or higher ft/lbs than the other bones though (of course they will withstand more load over the duration of the twist before giving out).
HPI's as ever, are expensive for what you get.

The next things to test - how much torque is generated at the drive cups (how does it compare to the amount of torque required to snap bones), how much torque can the drive output cups and axle cups withstand before failing.
 
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I wish I could test the tourque at the cups from the engine. I don't know of any way to do that. We would need a chassis dyno. Like 1:1 cars. As far as teh cups, I've never seen one break. They just get grooves wore in them. I would suspect that they wouldnt break because of the diff action and slipper settings. I don't think the truck could snap them. I will be testing those soon though just to see.

I knew the Ti bones were weakened from the first test, but they still performed impressively in the second. I don't think the savage is capable of snapping them. Probably not the IRC ones either.
 
I think that's about the size of it - IRC and Ti bones will handle what the truck can throw at them. It's too hard to test torque output at the drive cups and the axles would be subjected to no more stress than the drive cups.
Did the Ti bones have any memory left in them after the twisting (ie did they try to straighten/flex back)? I would have thought after the twisting it would have lost most of that property?
 
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