Spring/wave washers?
 

What's with Porsche's decision to use spring washers? I was getting ready to button up the cam tower housing when I realized the PO had flat vs the wave ('spring' in PET) ones that Porsche used.

Safe to use conventional steel washers here? What about other locations?

https://www.pelicanparts.com/More_Info/N0122418.htm?pn=N012-241-8-OEM

They are a form of lock washer. In theory, they provide some extra tension to keep the threaded assembly from coming apart. I have never really understood why this is so, as any force applied by the washer is a tiny fraction of the strength provided by the bolt stretching.

Maybe I was sleeping that day in engineering school.

Here's a video on the performance on different kinds of spring washers, nylocks, and even double nuts on a Junkers Vibration machine. In heavy rail, we now use Nord-Locks on critical bolts. Nylocks WITH a spring washer would still loosen up on the wheel trucks. Steel on steel from the wheels rolling on the rails causes some pretty harsh conditions for fastener tension.

https://www.youtube.com/watch?v=tAQUycabc9Q

I'm just not sure why they're used in 'non-critical' areas like the cam housing. And the amount of tension they would add seems like a rounding error. A couple of the used one in my engine came apart--when's the last time you saw a washer fail??


Some other relevant reading: https://engineerdog.com/2015/01/11/10-tricks-engineers-need-to-know-about-fasteners/

Yup, a regular spring washer is not even comparable to a Nord Lock or a Schnoor. I keep a drawerful of Schnoor washers here at home. I think Bel-Metric sells the Nord Locks.
Nice video, BTW.

Another thing to consider with the wavy washers is the fact that they are hard steel and thin. If you replace them with a normal washer that is not hard it may deform. There are also some situations where a thick washer may be too thick for the stud and nut.