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+--- Thread: Washers under Big End Nuts (/showthread.php?tid=6152)
Washers under Big End Nuts - Jamie - 23-05-2021
Daft question, no doubt, but do people use plain, spring or no washers under the big end nuts? Instinct tells me to use plain washers, but I am not sure.
Jamie.
RE: Washers under Big End Nuts - Robert Leigh - 23-05-2021
Bigend nuts should not need washers. Originally they were split pinned and the nuts are sized for the castellations to be correctly positioned for the split pin. I have found stretched bolts where washers have been added to create the correct location for the split pin, but this has been the result of the bigend bolt being stretched by overtightening. Such bigend bolts should be scrapped. Many of us (most?) now use self locking nuts which avoid the problem of the split pin not lining up with the castellations. The bolts locate in the top half of the bigend so neither the bolt nor the nut can turn, obviating the need for any washer.
RE: Washers under Big End Nuts - Ruairidh Dunford - 23-05-2021
Some of the nylocks sold for this application are not quite tall enough to get a socket on and will need a washer to lift them up slightly.
I have always used good quality spring washers for this - no doubt this is incorrect but continues to work, without any issue, for me over a thirty year period in hundreds of engines.
RE: Washers under Big End Nuts - Jamie - 23-05-2021
Thank you.
RE: Washers under Big End Nuts - bystander - 23-05-2021
Washers found under big end nuts may also be a sign that the caps have been filed in the past to take up wear - a common bodge in days of yore.
RE: Washers under Big End Nuts - Bob Culver - 26-05-2021
Ordinary spring washers come in two forms; with and without a burred end. Tha latter seriously alter torque and the bolt is loaded eccentrically. I doubt if the other type contribute much. If the cap faces abut soundly, threads do not run out, not soft low grade nuts, no dirt, heads seat securely, no lock required. Very many old bolts are waisted , presumably due lazy mechanics tightening to the next slot. Adjusting the faces can be tedious and all have to be kept in order..
RE: Washers under Big End Nuts - JonE - 26-05-2021
I've just bought some Philidas locknuts - apparently they can be re-tightened 6 times - as someone had mentioned that some nylocs weren't up to same standard they used to be decades ago. So worth making sure you are getting nylocs from somewhere reputable like a 7 supplier. Be interested to know whether any bad points about Philidas?
RE: Washers under Big End Nuts - Colin Reed - 26-05-2021
HI Jon,
IN The aircraft industry it is not recommended to (reuse) any type of self locking nut on any thing that rotates or is subject to vibration.
They are not expensive, so why bother it could end up being expensive
Colin
NZ
RE: Washers under Big End Nuts - Rogerfrench - 26-05-2021
Washers can be used to balance a light big end.