Proper method for determining bearing clearances?

nm9stheham said

BTW, on the re-use of the bolts..... I suspect a lot of failures in the past could be traced to inadvertent overtorquing. I bet there are a ton of guys who are sloppy in their work, and who don't clean and dry the threads on rod bolts before torquing them. It's pretty critical on SBM rod bolts, because the book torque of 45 ft lbs is right up near the limit of the bolt torque IF the threads are dry. If they are oily and you put 45 ft lbs on them, they are going to be well past the max load of the bolts and into the yield region.

Click to expand...

You are correct...

The lube can make a HUGE difference in the clamp load for the given torque...

If you put too much or a different lube on the bolts, then you will affect the clamp load for that given torque...

If someone tried to re-oil the used connecting rod bolts in our factory, we would get many reject failures on the multiple nut runners that tightened them... we ended up having to save all the used ones and send them back to the manufacturer and they would re-coat the special oil/wax coating for us... Then we would batch run them at one time to keep track of them as they were more sensitive to fail in the torque station....

Fastener Engineering develops the torque specs based on how the parts come into the factory... The torque specs were set up to be on how the parts came in new with whatever coating was specified,so adding any extra oil/lube will throw off the torque specs...