I was the same way with old bolts up till this winter. Then I was informed from a local machinist / builder that over time bolts and threads stretch out of spec. Once out of spec a bolt or nut can wear away / deform / damage the threads even if the worn out of spec hardware looks good. Now I have a new box of bolts like those shown above for building with on serious projects. I still have used bolts for rinky dink projects and when needed for hand tightening assembly of works in progress.
Welllllll, not so much if engineered torques are followed. While there are a few exceptions (very hot items) to this, the majority of stretching happens from over torquing. I use a torque wrench for very nearly everything.
Being in aviation my entire life (stitching cloth wings at 12...) I came to appreciate proper torque and repeat use of fasteners.
[/quote]
If engineered torques are followed is the catch. I am not saying that it isn't possible to take care of bolts. I am just saying that used hardware removed from beat up parts or project bikes probably isn't the best choice to install into a bike build that matters and/or is of value. Very few if any DIY or Pro mechanics work on dirt bikes to aviation specs let alone OEM factory specs. This combined with the general abuse that essentially all dirt bikes will see in their life pretty much throws engineered torque values out the window. Once a dirt bike has left the factory and been ridden to the point of "parts or project" its pretty much a guarantee that not only will it have some stretched bolts but will also have damaged threads, tweaked fasteners, ect. Most average good condition used dirt bikes have some hardware related quirks too even if only a few years old. That is just the nature of dirt bikes. Once a bike leaves the factory all bets are off on engineered torque values being followed. This combined with the abuse a dirt bike will see from average riding leaves some hardware questionable after the first 50 hours of a bike's life and most hardware questionable after 100 hours of use.
In addition to the machinist pointing out the obvious too me, I have stripped over 20 bikes the past few years salvaging parts for various projects including a couple bikes with only around 30-50 hours since new. Every bike I pulled apart had some bad hardware. Anything that felt or looked bad got tossed. What appeared good was saved and as noted will be used for various projects though not on any project that matters. If it matters new hardware is the only way to go to ensure engineered torques were, are and will be followed.
