Posts
2650
Joined
4/1/2008
Location
MA
US
Edited Date/Time
4/27/2019 9:57am
What is the purpose of these? A buddy of mine just did his top end and he replaced them. But before finishing the job and after the head bolts had been torqued, he realized that the head needed to come back off. The washers have been flattened but never heat cycled. Can he reuse them or are they truly one and done once they’ve been crushed flat?
Consider this, in order for that lock washer to begin becoming useful in holding a nut on, there would need to be a physical gap between the nut and the washer forming. At that point, considering this is a head nut, you've already lost the critical tension and "stretch" in the head studs that keep the head firmly in place, ie the damage is already done. Once that tension is lost, you've already lost your head gasket and likely dumped cool and into your cylinder, no Bueno. I don't see any reason not to just replace those with regular copper washers.
Yeah, how about we go screw up your hard work because, yaknow it makes not difference?
I'd stay with stock. There's a brazilian reasons to stay, and one to fuck it all up. Jus' sayin'
The Shop
1. A different washer is not going to change electrolysis, and good coating of anti-seize will keep those nuts from welding themselves to the studs. Everyone should be using anti-seize on their cylinder and head nuts.
2. If it took them 8 months determining he proper pressure on those threads then god help them, they need it desperately. The stud diameter is known, we want the tension in the stud to approach its yield point so that under the cyclical loading it undergoes during each engine cycle, it will not fail in fatigue because the applied load will not exceed that of the pre-tension inflicted on it during tightening.
3. Just because something left the factory a certain way, doesn’t make it correct. Here’s an example:
Cr500s do not have alignment dowels for the head to cylinder interface. They rely only on the studs to align the head. This is not an optimal design, nor is it technically “correct”, since studs and bolts should not be used to align parts, that’s what dowels and pins are for. It ended up working, but the design could be better. Since wave washers are being used here I’d venture to guess it’s an older bike as well.
I’d recommend looking into Carrol Smith’s theory on bolted joints and the use of locking washers. He will go much more in depth than I could ever hope to and explain things in a way that probably is easier to understand and more enjoyable to read than my bumbling.
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