What filler metal to join crankshaft parts? 1

[qcrobert]

Would like your opinion (or best guess) on what filler metal and welding process you would use to stitch weld a bushing to the flywheel of a motorcycle?

Please see attached sketch of crankshaft part assembly and PMI of flywheel and bushing.
Thank you your time
Robert

 

[Tmoose]

Are those pictures of your actual components?

PMI strike again.
43% zinc just ain't right. I'm guessing the "bushing" is the end of the fancy hardened steel crankpin, and the PMI picked up some plating of some kind. Maybe somebody aimed at the plated steel plug used to seal the hollow crankpin. I'd gently mechanically clean the end of the actual "bushing" and repeat the test, all the while remembering that not knowing the carbon content makes pOsItiVeLy IdnTifyIng any ferrous alloy pretty much out of the question.

Is this is to attempt to keep a new pressed together crank from slipping out of true in abusive service?
A popular method was to TIG braze or TIG weld the joint with stainless filler as shown in your picture.
Keeping track of the crank alignment "truth" before during and after the TIGging is real important. Not just a welding job. Not even close.

If this is to patch together damaged goods the process would be the same but with lower expectations of success.

 

[meltedEng]

Is you machine calibrated to analyse these materials?

We have welders in our shop try to PMI stuff and ask me constantly, but our machines aren't calibrated for it.

Anyway, I think most likely you have a fancy new part that has a plating. 70Zn-30Fe. Sand it off?

 

First ask yourself "what is the potential downside of this part breaking up on the road, at speed?"
(And it will only break up at speed.)

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[BrianPetersen]

Welding crankshafts in the manner shown is something that was commonly done "back in the day" to certain high-performance two-stroke engines to stop the crank from "walking" under severe loading conditions. Find a motorcycle shop with an old skool mechanic who knows two-stroke Grand Prix racing motorcycles. (Such people are indeed getting rarer, but they are out there.) They will know exactly what needs to be done.

Take into account the availability of replacement parts before doing this, hence why I would certainly not try this myself.