Half Shaft dab?

[Michael H.]

Re: Half Shaft dab?

Mike, I am confronting the identical issue that you raised about how to restore the half-shafts and drive-shaft to their original finish and sheen. No one seems to think it can be done short of having the shafts "re-tubed." But like you, I am determined to try. I have found that sanding down deep enough to eliminate most of the pitting on a used shaft and then progressing up through finer grits of sandpaper results in the shafts becoming too shiny (and maybe also too smooth). Graeme suggested using Dioxidene... but I don't really know what that is and, in any event, I can't seem to find it. I thought of using another kind of readily available heavily diluted acid-based mixture, but I'm pretty sure that would simply etch the shafts--which I assume again would produce the wrong finish.

A friend of mine suggested blasting the polished shafts very lightly and from a distance using walnut shells as the medium. That's something I might try and simply wanted to share it with you. You mentioned scoring the shafts length-wise to replicate the extrusion marks, but if they were originally a flat piece of rolled metal, I assume they would not have such score marks? But both the half and drive shafts should have the longitudinal (lengthwise) seam, right?

One thing that confuses me somewhat is how the seams were originally welded length-wise. I have seen pictures posted here of an original shaft displaying about a quarter-inch wide longitudinal seam that is very straight and of even width. (It would be great if someone could post a good picture showing such a seam.) But there were no apparent grind marks around this smooth bluish-colored seam. Were they welded from the inside using some type of automated method, leaving just the welding burn marks on the outside? Is it better in the view of the experts here to replicate the weld marks on both the rolled ends and the longitudinal seam using a torch versus the "gun blue" chemical? If the torch method is more realistic, how could one replicate the very straight and constant-width longitudinal weld using a torch?

[Wayne M.]

Re: Half Shaft dab?

....One thing that confuses me somewhat is how the seams were originally welded length-wise. I have seen pictures posted here of an original shaft displaying about a quarter-inch wide longitudinal seam that is very straight and of even width. (It would be great if someone could post a good picture showing such a seam.) But there were no apparent grind marks around this smooth bluish-colored seam. Were they welded from the inside using some type of automated method, leaving just the welding burn marks on the outside? ....

Michael -- if you're referring to my post # 21, above, here's a pic and a close-up of the heat-affected zone and weld line on the "other" half shaft [both off the low mile '64 rear suspension -- stored since 1968]. IMO, the only reason we are able to see the longitudinal seam is thanks to the generous "black substance" that was applied to trailing arms, etc., in that time frame.

Being an old pipeline engineer, I believe these shafts were manufactured by the ERW (Electric Resistance Welding) process. A coil of flat steel of the width required to form the circumference was fed first into "U & O" dies [describes the shape of the strip after exiting each of the two forming steps, with both edges abutting each other. Then fed into the stationary welding apparatus where external electrodes contact each side of the (future) seam. Heat generated fuses the two edges together.

The 1/4" seam (deeper blue in the pics below) is where the metal would be in an almost molten state; the blueing on either side of that zone is just the effect of heat.

[Mike Z.]

Re: Half Shaft dab?

Michael, glad someone else realizes the details of what I have talked of. I tried the walnut shell media-didn't work (does not work to dull, but walnuts shells work great to blast paint off), I checked into the Doxidene and everything I read said it turns the material black, which is not what I am looking for-same for the gun bluing (actually turns black not blue). I got an OK look from a green 3M pad running it length wise, but still not satisfied. I have the last few days thought to go back to what the factory did-shot peening (on the BB shafts). This seems to be a process not often used anymore, but still is used I understand to destress welds-so looking for someone to do the process-will let you know how it comes out.
The BB shafts were shoot-peened and after I get these done I will know how it comes out. The tube of the shaft, as I understand it, were welded length wise while being extruded through a dye-that's why the weld you refer to, but also length wise marks (mentioned in the JM) as the metal would stress through the dye. I also believe, the BB shafts, due to the shot-peening process would no longer have this weld evidence. The shot-peening would, I believe (and remember from many years past doing race motors, etc. that we would have parts peened) leave a more uniform finish and the weld tracings both length wise and at the yokes would no longer be evident. I may never know if my belief is true, since my shafts presently are smooth as glass and look like chrome (the buffer really polished them). Perhaps if anyone out there has a shot-peening machine, they can tell us what they would expect would have happened to the weld tracings, originally. Then after the shot-peening process, was a preservative then applied? Not sure the process Warren would have used-just more questions.
Mike