Locking washers and washers of any sort.
I was thinking this the other day when I changed a broken spring. The top of the strut was held to the inner wing with three nuts that had a wider base. These chewed up the paint as they were tightened. Probably wouldn't have happened with a washer in there.
|
|
If the car manufacturers can save a few bob by not fitting a few hundred thousand washers, (or anything else), per year, I am sure they will. They won't be worried about your chewed up paint, it's out of sight, and the galvanised panel will last any warranty.
Last edited by: Old Navy on Sat 21 Aug 10 at 12:55
|
There shouldn't be any problem getting them for your own use.
I have enough spring washers to last a lifetime, I use star washers, both external and internal grip, regularly. My engineers supplier has huge stocks. He can even supply Thackray washers and Oddie nuts out of stock.......although they do have a patina of rust, being ordered about 1930 !
Ted
|
>> Thackray washers
No-one knows what thackeray washers are any more. Woodruff keys are completely forgotten, too. All sorts of things ditto.
"Forgotten mechanical things/skills" thread, anyone?
|
>>Woodruff keys are completely forgotten.
Cotterpin anyone?
|
How about a giggle pin ?
The engineering one !
Last edited by: Old Navy on Mon 23 Aug 10 at 18:54
|
Shakeproof washers have been proved to be a bad idea. For many years, best practice has been to have either a solid washer or a washer built in to the head of the bolt. The bolt is (I believe) tightened to produce an axial load just beyond the yield point of the material. For consistency, it's important that thread surfaces should be dry. Some installations are tightened to the yield point, and then an additional amount of rotation is applied. Induced loads depend on the surface treatment of the threads of the two components.
Shakeproof washers? Eugh!
For a more lucid explanation we need Number_Cruncher.
|
I think the short answer to the question is:
nylock nuts.
|
...I think the short answer to the question is nylock nuts...
A slightly longer answer to the question is Philidas nuts.
Eh?
www.bolts-nuts-washers.com/philidas%20nuts.htm
|
|
I'd accept a nylon insert nut where the bolt is effectively a largely static pivot pin and there is a clearance between face of the nut and the adjacent component.
|
L'escargot is exactly correct - shakeproof washers, spring washers, in fact, anything which interferes with the joint becoming solid and stiff is an awful idea.
Sensible manufacturers have abandoned them not from petty cost saving, but from the motivation of design hygiene. If I were given responsibilty for any system containing them, re-qualifying and re-testing the equipment without them, and then deleting the horrid things, would be an immediate priority.
Bolts with an inbuilt hard flange washer are excellent - the washer hardness is known, and can't be downgraded in field service, and one interface where embedding could occur and reduce bolt pre-load is eliminated.
So, shakeproof washers? - confined to the dustbin of naff ideas from the past is the answer!
Nyloc nuts do have their place - but, they shouldn't be used ad-hoc, where a plain nut was previously specified, because the friction affects the torque / preload relationship, and if the standard torque is used, the joint will not be correctly pre-loaded.
Last edited by: Number_Cruncher on Sat 21 Aug 10 at 19:15
|
>> spring washers, in fact, anything which interferes with the joint becoming solid
>> and stiff is an awful idea.
Shakeproof washers aren't used in high-load situations, are they?
When a "spring washer" is used, why is the "joint" not solid?
|
Shakeproof washers certainly shouldn't be used in high performance joints.
Spring washers tend to cause embedding problems and burrs which can reduce the stiffness of the joint. Should be banned from any decent design.
|
the most important thing to remember with these shakeproof washers is the final tightening comes down to the individual and thats a bad thing
i never liked them
ever
much prefer loktight as the final solution if a locker is needed
or wires through the nut as the even best er solution
|
|
Not sure I like the sound of that BB, but then I'm not a very technical sort of person....
|
>>much prefer loktight as the final solution if a locker is needed
>>or wires through the nut as the even best er solution
Loctite can be a good solution, but, only if it was originally specified in the joint. Loctite really screws [sorry!] with the relationship between torque on the fastener and preload, and you can end up with a bolt which has had the right torque applied, but hasn't reached the right preload. If I were specifiying a joint to use Loctite, I would have to test the torque / preload relationship first to gain confidence, before submitting the complete system for testing.
Any locking device which changes the friction relationship can be useful, but, the torquing procedure will be defined during design or development to account for it. Fitting such a fastener in place of a standard one, and then using the torque spec for the standard fastener is dodgy to say the least.
Wire locking prevents the fastener unwinding - but, embedding failures and gasket settling can [and do!] give rise to joint failure without the fastener head rotating at all! Preventing fastener rotation prevents many, but not all joint failures.
In mentioning embedding and gasket failures, I'm talking about joint relaxation which is of the order of a few tens of microns leading to near complete loss of tension in the bolt.
|
>>wires through the nut
Quite common in competition vehicles.
|
just to update i only use Loctite if i feel the situation needs it ,i wouldnt use it as defense against proper tightening procedure
in fact Loctite is my last line of defence in case i arent sure of a possible outcome
example i Loctited the securing bolt on a mercedes sprinter yesterday (the steering wheel bolt),the owner said if the wheel came off in his hands he would brake but i noticed the thread had some blue on it so i Loctited it as i saw it may just sometime in the future undo even though i know in my heart it wouldnt and being a commercial i had no access to torque data so made sure the nut was tightened up to a mark i made prior to undoing it
|
The nuts with wide bases may technically be superior, but they make life much more difficult for DIY repairers trying to get them undone. When rusty they lock solid onto the bolt anf the component, and often require an inordinate amount of force to shift.
I wrecked a perfectly good starter motor merely by undoing the nut holding the cable, because the brazed attachment of the other end of the post ripped out of the motor.
When an old fashioned nut and washer are rusted solid, it is usually possible to chisel the washer loose, which allows penetrating fluid access behind the nut and makes removal possible.
They are a pain on Volvos. Whenever I encounter one I replace it with a "proper" nut and washer from an earlier model.
|
>>
>> Nyloc nuts do have their place - but, they shouldn't be used ad-hoc, where a
>> plain nut was previously specified, because the friction affects the torque / preload relationship, and
>> if the standard torque is used, the joint will not be correctly pre-loaded.
>>
>>
Especially so if there is any heat involved, for obvious reasons. I've known people use Nyloc nuts to re-fasten motorcycle exhaust manifolds, with predictable results.
On older vehicles, though, especially motorcycles where vibration is a constant enemy of fastener security, it is not a good idea to deviate from the manufacturer's specification when rebuilding. Had an incident on one of my old side-valve Harleys where the previous owner had neglected to bend the lock-tab over on the final drive sprocket, resulting in the said sprocket working loose and losing drive.
|
Tab washers are a bit of a mixed blessing. While they do prevent the fastener shaking completely loose, by default, they need to be made of soft metal to allow them to be bent over - this soft metal then forms part of the joint, and suffers embedding problems, leading to loss of preload. While they do have uses, they have no place in any high performance joint design.
|
made of soft metal to allow them to be bent over - this soft metal then forms part of the joint, and suffers embedding problems, leading to loss of preload
>>>
>>>>>>I can attest to that when the halfshaft came out on my mk1 luton transit twin legger
ive always used new tab washers on these fords since even..........
|
>> Nyloc nuts do have their place - but, they shouldn't be used ad-hoc
I hadn't seen a Nyloc nut for years but, bizarrely, ended up using them at the weekend. The application? An IKEA bed! The chassis (or whatever it's called in bedspeak) is fixed to the frame using 4 Nyloc nuts.
I guess Swedes expect high vibrational loads when using their beds...
|
|
All that shivering I expect
|
Whatever happened to 'shakeproof' washers? - Old Navy
