building a cobra from basically scratch

[BBQCYCLEWERKES]

Originally Posted by thefordguy

I have a question I thought of today. I'm not saying any of you are wrong at all. You say metal fatigue and molecular realignment at the weld, driveshafts are welded together and they spin in excess of 6000 RPM all the time. I'm not trying to be a smart ass, I just want to know why a driveshaft welded together is OK but a water pump pulley is not? It spins the same RPM and has much less load. Again, not saying your wrong or trying to be a smart ass, just curious.

A driveshaft is balanced for rotating weight after is it welded. Any misbalance in the pulley will cause fatigue and cracking. Also, there will be tension on the pulley from the belt which will cause addt'l metal fatigue if not balanced. A drive shaft is also welded on a fixture and in most cases computer assisted welding equipment used. This is not only to make the welds pretty but used to set the temp more accurately to decrease the metalurgy issues from welding. I can understand your welding the pulley if this was your car as you would then assume the risk, but this is not the case. You are potentially playing with the life of another person here and if failure accures with damages, you cana be held liable. Just looking out for you as I realize you are doing the best you can. I was young in the auto fabrication field years ago and wished I had more people looking out for me and mentoring me back then. Best of luck and I hope the worst case never happens.