What's this nut?

[made2care]

Placing wheel back on bike. When checking with repair manual it shows washer, locknut then nut. The previous owner only had this nut on. Is this a locknut of sorts? Notice the two thin metal strips?
Would you replace with new and go with lockwashers?
Thanks again.
P.s. This tightens the axle holder.

[bustedwing]

That's a self locking nut and a used one will not work as well as a new one. You will either have to replace it or use loctite. Loctite has several different strengths, the strongest you would have to use a torch to warm up the nut to break it loose, which is a little overboard. I would recommend the weakest as long as you torque the nuts properly. Ride safe.

[WingAdmin]

That's a type of locknut (if I remember correctly, a split beam nut, but don't quote me on that) where the little metal tab gets pulled inward as it is tightened, increasing friction.

Like bustedwing said, locknuts should not really be used more than once. Whether I'd replace it with same depends on where exactly it's being used. If it's not that critical, then perhaps. If it's a critical component, I'd probably source the proper replacement items.

[Mh434]

Personally, when I find fasteners like that, I tend to replace them with stainless steel nylock nuts. They stay in place, don't corrode, and are reusable a few times (no self-locking fastener is infinitely reusable). Can be hard to find a source, though - they need to be metric on a 'Wing...

Failing that, where there's enough threaded shank available, two regular nuts (with the outer one used as a jam nut) works great, and IS more or less infinitely reusable.