As I reassemble my engine compartment, I am replacing the fasteners with their corresponding new ones. Which begs the question - what is the logic for using wave washers vs. lock washers - is one better than the other for a specific use etc?
Lock washers vs. Wave washers - when and why?
- Thread starter Stevehose
- Start date
BOTH the grower DIN7980 and the spring DIN 137 provide a tension that blocks the head and refrains from get loose under vibrations
the grower may have spikes or be completely flat, the one with spikes provides an extra safety but damages the seat surfaces
i will follow what the exploded view of the BMW book says
the grower may have spikes or be completely flat, the one with spikes provides an extra safety but damages the seat surfaces
i will follow what the exploded view of the BMW book says
I have seen recent studies, I think it was NASA, that showed lock washers don't work
But I couldn't bring myself to not use them, sort of like buying bonds
If you want them to stay on use loctite or similar
But I couldn't bring myself to not use them, sort of like buying bonds
If you want them to stay on use loctite or similar
just did a little Google, there are NASA studies, split washer worse that useless
here is an interesting video, 'friction doesn't work'
here is an interesting video, 'friction doesn't work'
Yes me too - was wondering why one situation calls for one style vs the other.
Wave washers are not intended to lock things; they are intended to provide a spring force to the elements it joins, often where relative rotation movement is specifically allowed. A bolt that acts as a hinge for instance, where the surface under the head rotates relative to the head. In such case, the rotation could run the nut off. The spring force of a wave washer is much lower compared to what the bolt is capable of.
If you tighten a bolt with wave washer to its full load, a wave washer is just squashed flat. Essentially becoming a flat washer.
Lock washers do aim to lock the nut to prevent unintention rotation mostly occuring due to vibration. But they actually aren't really good at it as it turns out.
So the wave washer isn't designed for locking, and a locking nut isn't even terribly good at it's job either.
As such lock washers have been withdrawn from the DIN standard as a locking solution around 2003.
In severe conditions adhesives (Loctite), or Nordlocks are simply better.
I do use the Nordlocks sometimes, they're great, but they are about 1 euro/usd each.
In our cars, just use what the engineers wrote in the parts books. Even our brakes are fixed with nuts.
Time has prooven that is good enough.
The whole car industry is doing that for >50 years, and our highways are not littered with e9 brake parts around each corner.
That said, modern cars do use loctite on the bolts holding the calipers as it is an extra assurance against improperly tightened bolts.
If you tighten a bolt with wave washer to its full load, a wave washer is just squashed flat. Essentially becoming a flat washer.
Lock washers do aim to lock the nut to prevent unintention rotation mostly occuring due to vibration. But they actually aren't really good at it as it turns out.
So the wave washer isn't designed for locking, and a locking nut isn't even terribly good at it's job either.
As such lock washers have been withdrawn from the DIN standard as a locking solution around 2003.
In severe conditions adhesives (Loctite), or Nordlocks are simply better.
I do use the Nordlocks sometimes, they're great, but they are about 1 euro/usd each.
In our cars, just use what the engineers wrote in the parts books. Even our brakes are fixed with nuts.
Time has prooven that is good enough.
The whole car industry is doing that for >50 years, and our highways are not littered with e9 brake parts around each corner.
That said, modern cars do use loctite on the bolts holding the calipers as it is an extra assurance against improperly tightened bolts.
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found these tests disturbing
similar to some test they use to show the benefits of engine oils
i wonder if the conditions tested ever occur in an automotive application
p.s. it is a good test to sell nordlock, but why do they use copper grease to coat the threads ?
What the studies show, lock washers don't work, they didn't know that in 72'
The system they show in the video digs into the surface so it would be a rust problem, but I think this is for bridges and things like that, that are painted after build
Grease the thread to get proper torque
And right, the cars don't fall apart so not something to worry about, but at the same time, don't worry if you use a split, serrated, or flat
The system they show in the video digs into the surface so it would be a rust problem, but I think this is for bridges and things like that, that are painted after build
Grease the thread to get proper torque
And right, the cars don't fall apart so not something to worry about, but at the same time, don't worry if you use a split, serrated, or flat
grease ?
none of the threads in our coupes should be greased to get proper torque
all torque settings are for clean dry threads AFAIK
I didn't say for E9, in the test video they need to assure consistent tension for a valid test
here is an article, to be honest, it doesn't interest me enough to read it in detail,
www.hextechnology.com
the key sentence:
Using proper bolt lubrication practices will allow assemblers to achieve the ideal torque with a low degree of bolt scatter (which we define as differences among torque levels on different bolts holding together the same flange).
here is an article, to be honest, it doesn't interest me enough to read it in detail,
Bolt Lubricant and Torque: A Comprehensive Guide – Hex Technology
www.hextechnology.com
the key sentence:
Using proper bolt lubrication practices will allow assemblers to achieve the ideal torque with a low degree of bolt scatter (which we define as differences among torque levels on different bolts holding together the same flange).
BMW lesson I know of is only head bolts.
Taught to lube and sling off excess before torque. Big issue was at the washers being lubed as well as the bolt threads.
Taught to lube and sling off excess before torque. Big issue was at the washers being lubed as well as the bolt threads.
head bolts might be one of the few areas where even torque in a group is important?