These are the ones I am talking about - Not sure if they are 1/4" of 3/8" - been a while since I messed with them. Eitherway, they are small compared to the cross section of the axle.
As the old HAMB metallurgist, I can say that axle does look like cast iron for sure. Most likely grey cast iron, not nodular or malleable cast iron. I would need to see the actual part or at least better pics to say opinion on why it failed. The slight brown color specs are just corrosion best I can tell. There is not any significant defect I can see that would have contributed to the failure. Certainly this is cause for concern as the axle is stated as being essentially new. Forged will always have better ductility than cast. But that does not mean cast is automatically classified as unacceptable.
I doubt anyone producing axles today have the resources or desire to engineer their products as well as Henry Ford. Buy a Ford axle and give a HAMB member your business and have it dropped.
I can't keep up! In my simple logic, cast would always be inferior to forged, forged being pounded out of a solid bar, and cast being, well...cast. And where does that put the tube axle? I notice that Ford only did that for one year, correct? Why didn't Ford stay with the tube? Did any of the other car companies cast axles? Or is the cast axle a new phenomena created to keep costs down? You guys are making me re-think the T-bucket front end under my roadster!
Cast can have the same tensile strength as forged, BUT it does not have the same ductility. The discussion above and pictures show the forged axle can take a lot of yielding and not fail. A typical casting will have very little plastic deformation, it fails soon after the yield strength is reached. Forged will have a significant difference between yield and ultimate tensile strength. Tube axles are made from rolled and welded, or drawn material, and would have similar properties to forged. The ends being forged are similar to old Ford axle. The weld is where the problems are. You not only have potential weld defects, but also the thickness is different and you have heat affected zones to deal with. The good thing is the tube and forged ends are already at low strength, so the HAZ is not much of an issue. Any thickness transition will cause a localized stress concentration. Cast is done because it is lower cost. Especially for lower volume parts. Some parts have to be cast as other fabrication methods are not practical. Engine blocks or manifolds for example. A lot of new cars have nodular cast iron crankshafts. Not as good as forged, but nodular is much better ductility than the typical grey cast iron as found in engine blocks.
A few years back I got some early Ford repop front spindles from a then local supplier, on closer inspection they turned out to be cast Iron, probably high nodular but i wasn't taking any chances and ended up getting a pair of forgings. Just seemed a little scary to me to have all that weight on a little cast axle. They came in an un named box so theres a 99.9% chance it was crap from an oriental country!!
Yes, Bell Tech was the modern suspension line made for lowering C/K Series Trucks and later on Camaros, G-Bodies etc. Super Bell was a Vintage line catering to the Street/Hot Rod industry.
Kinda glad I put a 4" Chassis Engineering under my A. Hey Justin, you'd better hurry up and put these guys outa their misery before they start yelling at ya..... Just so you guys know, hotrodkiwi is not a troll or winding ya up, he works for a safety organisation specialising in modified vehicles, and gets to see more accident damaged vehicles in a year than most of us will see in a lifetime.
So is he in a position to have information on the failure mode? Was there forensic investigation? Results? Bob
Hey, and whats up with the "nylon" shackle bushings? They have been replaced with a cheap plastic version of the same. Was trying to put them in a spring the other day and they just mashed flat and broke off. When did the switch happen? I never got that memo!
Thanks, 38 Chevy! My mom was a metallurgist, so I kind of understand the plasticity of metals...Cast is more brittle, therefore will fail while forged is still in the process of deforming. Got it. BTW, got my bear Claws, nice! Thanks, Mike
Another thread with more of the same . . . http://www.jalopyjournal.com/forum/showthread.php?t=297140&highlight=axle&showall=1 And in that thread I posted this: Since this post was brought up in another debate today, I thought I'd add my experience just to muddy the waters. For what it's worth, mine was a Superbell. This is how it came out after a 45 mph head-on collision (70-80 mph combined force of impact). And here is where it lives now. As you can see it bent, but did not break. I was quite impressed. I've since ordered 2 new Superbell axles for my Model A projects - one plain 4" drop and one plain 4" drop and drilled
Thank you for sharing this - (glad you are OK and sorry for the accident) It bent because those are made of DUCTILE CAST IRON 65-45-12 !!!! It does deform. Everyone (the son of the metalurgist and the metalurgist especially) just drops the ductile part and says "cast" and then follows comments that "it'll just snap" to sound more dramatic I guess. It seems to me they are insinuating all axles that are not forged are plain cast iron. I think the clarification between plain and ductile cast iron should be maintained. Something different is going on with the part shown at the beginning of this thread. No idea what, it actually might be an axle made of "plain cast iron" which would not be good. I don't think Superbell or Speedway would pedal axles that would snap if subjected to a shock force. The liability would put them out of business. I agree a ductile cast axle will deform and then snap in a collision versus a forged axle would just deform wildly. Eitheway the axles are toast. I don't agree a ductile cast axle will just snap pulling into a drive way.
Okay. What about the normal twisting effects of using split wishbones? Can the "ductile" iron handle it, or not? Bull's pictictures seemed to show that they can twist at least once, without breaking, but I do have to wonder about it happening over and over again under normal driving conditions.
That's funny because the foundary only messes up the casting process and never the forging process! What if they get the heat of the pressure wrong? you'll have similar issues
I highlighted your text in red and quoted mine for reference. What part in mine states what you said in red? Answer: none. I stated there is a difference between grey cast iron (as you call it plain cast iron) and ductile or nodular cast iron. Be careful accusing people of things and stating out of context that are not true! If you want to have a metallurgy discussion, stay with facts.
You talked about forgings and their ductility then stated - "A typical casting will have very little plastic deformation, it fails soon after the yield strength is reached." Not true for ductile cast iron. You fail to reference Ductile Cast Iron until your vety last comment you include a tid bit about nodular iron crank shafts and their ductility. I think, if you were being fair to DCI - you could have mentioned it there and been less skewed. All I am saying is Ductile cast iron will yield and bend as proven by the pictures of the axle from the crash. It seems people go directly to assuming the axles are made from normal cast iron and will snap on any impact and that simply isn't so. I'd like to see the other half of the axle in the picture that started the thread. I wonder if that half shows any bending prior to it breaking. I agree forgings are better.
Good point here too - I think the normal twisting would have to deform the metal to work harden it which would then make it brittle and then eventually break it. I don't think the normal twisting would work harden it or eveyone would be riding around with a time bomb. I'll let this one up to the metalurgists out there and certainly the son of the metalurgist.
For those that want to actually learn about the difference in ductility/malleability instead of turning it into an argument, there's lots of info available in about 5 seconds. The lowest strength grade of ASTM ductile iron has a 40,000 psi yield and 60,000 psi ultimate tensile, and elongation of 18%. Medium carbon 1035 steel has a yield of 39,500 psi ultimate tensile of 72,000 psi, and 18% elongation. I don't see a lot of difference, and none in the % of elongation. As the various grades of ductile iron increase in strength, % elongation reduces, but in an apples to apples comparison with a similar grade steel, the specs are similar. I said it in post 86 and I'll say it again. That failure appears to be a quality control issue. Sources on material specs: http://www.farrarusa.com/ductileironspecifications.html http://www.metalmartusa.com/item.asp?id=36 Bob
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