O. K. guys look at these two pictures, especially the second one. Looking at the end of the rod at the one o'clock position, you see a "nub" that results when a rod fails in a torsion load. This could be hydrogen embrittlement that weakened the member and when loaded in torsion it failed. That would explain the fact that both rods failed in the same location. We absolutely need to know how these members are used in the suspension system and then we can know how they are loaded.
Any electro plated hardened steel must be baked within a short period of time from the plating process (This includes nickel) to prevent embrittlement. That includes Zinc, Cad Crome, Etc. You can't do that bake years later to prevent this embrittlement.
Is this part of a Jag rear end ? It looks very similar to the pieces on this Jag tubular control arm.
They look like radius arms off an IRS to me. Recently saw an article in "rod&custom" stating that you could put the forward end of such rods anywhere - it doesn't really matter. WRONG. If they are in the wrong spot they will fail, plated or not. We need more from GreggAz Re application.
Well, the ring of difference around break needs '38 Chevy to explain...gotta be either a hardened **** part or oplating doing that I'd think. But why no pics of the installation?? It is highly interesting that both broke a t same place, and not at obvious trouble spots like the probably lathe or die cut threads. What in hell was at that location on the car? What stressed that point?? Lots of street rods are running around with bad imported steel, cast fittings, cut threads, and chrome, and most survive despite all the ****...something happened at the 3/4 point on those parts!
Maybe they bottomed out against the frame or a crossmemeber, causing them to break in exactly the same location at the same time. I dont know anything about hydrogen embrittlement, but the way some others have explained it probably caused them to snap instead of bend.
Outer layer is brittle all the way around. This could be from case hardening or the plating, but probably a combination of both. Outer layer cracked all the way around causing a high stress concentration. Load had to be a reversing bending stress, similar to bending a paper clip back and forth. Failure of the inner section is from this reversing bending stress and the cir***ferential crack in the brittle outer layer.
The Jalopy Journal
