Inliners International Forums General Discussion MOPAR Crankshaft Welding

Hey guys!

Maybe you guys can help. I had the rear main seal surface on my early 50's Dodge flathead 6 (230 cid) crankshaft welded up. I had this done because the surface was corroded and was undersize, so it would have allowed some leakage. The rear seal surface is not a part of the flywheel flange, but rather it's a journal just behind the rear main journal, so it transmits the torque of the engine, but doesn't see any bending.

First of all, the machinist did not do any preheating or postheating of the crankshaft. Also, when he got done, there were some pits here and there left over from the welding. The place where the seal touches is smooth, but if you go more than 1/8" forward or aft of that, there are some weld pits that I believe come from the "valleys" between the weld beads. These "valleys" were not completely removed by the grinding wheel. I polished out some of the pits and found that some of them ended up being about 0.040" deep. There are still some left, though, and I cannot smooth them out without getting into the seal surface.

I was just wondering: Are results like these typical or acceptable? Will the crankshaft hold up? To me, it seems like these pits are places where the crankshaft could start fatigue cracking. This might not be a big deal, as the shaft may be beefy enough that it doesn't matter, but I just don't know.

The crankshaft is a forged steel crankshaft, not cast.


Thanks!!


Matt

Hi Matt,
Sometimes we tend to get carried away with the proper way to do things. Many times repairs are made that are not theoretically the best way to do the job, but work satisfactorily anyways. This shaft is welded at the end I see know reason it won't serve you well.
Jim R

Yeah, you are right. Sometimes I know I get carried away with the theory (I'm an engineer) and I don't necessarily have a good understanding of what is actually ok. I deal with aircraft parts, where something like this would definitely not be acceptable and would most likely cause fatigue failure.

However, in talking with several experienced people, especially other machine shops that do crankshaft welding, I think this won't be a problem. Apparently, some weld pitting is very common and acceptable, and most shops do not pre-heat or post-heat the crankshafts.

Anyway, thanks for the response!


Matt