Dog Bone Torture Test Results

[SV250]

Ok, got Kiz's package today. He sent me a few blacks and some black and HD center shafts. The results for the black 123mm were the same 6.5-7 ft/lbs. One went to seven.

The center bones were stronger. Both the black and HDs snapped at 10 ft/lbs. Two of each tested both ends. All went at 10. It seems there is no difference between the HD and black center shafts.

I paid careful attention to the flex amt. since so many people were interested. They all snapped in a 1/4 turn or less. If the blacks are more flexible,

[Salvaged]

Did you used a drive cup adapted to your torque wrench? How did the pins fair in the test? Any chance you have access to a durometer to check the softness/hardness? comparitively The Ti dbs may be really soft, which is why they twisted so much before they snapped.

Can you snap a picture of your test setup, so we can see.

thanks SV.... it's articles like this, that make you such a valuable forum member (/mod)

[SV250]

I used a socket that the pins fit nicely in the corners. The pins are really hard. No signs of hurting those. The Ti bones didnt start to twist until 19 ft/lbs past the snapping point of the others. I thing the drive cups or axles would break beffore the Ti or the IRC bones. I thought of another test for hardness. Hopefully the old bones are still in the can in the shed. Dont remember if I emptied it. I want to groove a socket to fit the bone, not the end and lock them in a vice sideways and test the torque req to bend them side to side. Not twisting.

[worstenemy453]

Now if your racing will your truck still go under the same stresses that your testing because i got the idea of some hollow tube from like lowes to make the dogbones - I want to try it but i dont wanna have to test it outside my truck lol - whats ur opinion

[Maxx_Savage]

The unit of torque is

force x length

ie Nm or lb.ft etc

[SV250]

Ok 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 dont know if this sheds some light on the flexability or not.

[PLUH]

Very nice test!!! I will be sure to make a mental note of this for the future when my dogbones need replacing.

One question though, and correct me if i am wrong, but could the fact that the hd bones tend t snap more than the standard bones be atributed to the rate at which load is applied to the bones (strain rate). If i am correct, the standard dogbones will have a higher toughness then the hardened bones (Toughness is defined as the amount of energy per volume that a material can absorb before rupturing) and an materials toughness decreases with an increase in the rate of loading.

It would be nice to see how these to dogbones fair if the same ammount of torque is applied to both at high loading rate, which is the case when you do a quick pull-away. In this instance i have a feeling that the stock bones will be better of than the hardned bones.

[SV250]

Thats what I was trying in the initial twist test. The twisting is teh same force taht the engine will put to the wheels. The HDs were barely stronger. They both suck compared to the IRC and GPM.

[Salvaged]

[quote="PLUH";p="672412"]Very nice test!!! I will be sure to make a mental note of this for the future when my dogbones need replacing.
One question though, and correct me if i am wrong, but could the fact that the hd bones tend t snap more than the standard bones be atributed to the rate at which load is applied to the bones (strain rate). If i am correct, the standard dogbones will have a higher toughness then the hardened bones (Toughness is defined as the amount of energy per volume that a material can absorb before rupturing) and an materials toughness decreases with an increase in the rate of loading.
It would be nice to see how these to dogbones fair if the same ammount of torque is applied to both at high loading rate, which is the case when you do a quick pull-away. In this instance i have a feeling that the stock bones will be better of than the hardned bones.[/quote]
Knowing terms that like, you've had materials science - which leads me to believe your an engineer? but not mechanical (or civil or structual) because you be authorative in this subject. So that leaves chemical, electrical, or aeronautic. I'll guess chemical.

[SV250]

Sounds like civil, structural. Def over my head. I dont know the terms, I just like breaking stuf.

[goingfknsvg]

So i just snapped my stock back dogbone, and called into my LHS to see if they carried any GPM Titanium Dogbones. And he was like "NO WE DO NOT CARRY THOSE TERRIBLE ALUMINUM PIECES OF #%^$ IF U GET THOSE YOU WILL DO NOTHING BUT SNAP THEM. I USED TO CARRY GPM WHEN THAT WAS ALL THAT WAS OUT AND THERE JUST CRAP". hahaha he was so *censored*! this is the owner of the biggest RC Shop in my area.  I just said oh okay thanks for the heads up, and hung up.  I guess this is when Ebay comes in handy.
-eric

[SV250]

Unfortuneately most hobby shops are only concerned with profit. They want to sell you whatever they have in stock or whatever they can make the biggest profit on. There are a few exceptions, but none around here.

[goingfknsvg]

What site do you recommend for buying the GPM Titaniums? Thanks in advance.  And thanks for puting on the torture test, really helps us newbies.

[Maxx_Savage]

Been looking in vain on eBay for those GPM Ti bones myself...

[KiZ]

[quote="goingfknsvg";p="672561"]What site do you recommend for buying the GPM Titaniums? Thanks in advance.

[mikland]

OUCH!

[-SavageSam-]

Like every thing in life quality costs, nice bones kiz and great reading here sv250.

[SV250]

[quote="mikland";p="672705"]OUCH![/quote]
Thats about double the HD bones, but youll save money in the long run. I have spent a few bucks on broken HDs beffore giving the GPMs a shot. Havent changed one since.

[Lunar_Wolf]

Money well spent imo, its not a massive amount but will stop your day ending early because a DB went.

[naynay]

I want to see the xl dogbones,it will be the differnece between some poeple converting to xl width and buying gpm i think.