Lock washers on brake caliper bracket bolts???

[Elektrishun]

I have heard of people using them when the bolt might be questionable but have never seen them in practice until today.

Checked the parts diagram I am using, called the dealership where I got the new bolts from and they checked their parts list, and I checked Rock Auto Parts to see if it's mentioned - no mention of lock washers.

Why wouldn't they use blue thread lock instead? The old bolt threads don't look mangled to begin with. Thick lock washer means less thread engagement. Old bolts are the same length as the new bolts that I will be installing. IMO it's poor workmanship if it was intended to be permanent. But what do I know. Not a mechanic.

As always, opinions are appreciated.

 

[DavidR8]

In my limited experience I have only ever used blue loctite when speced.

 

[Chicken lights]

Could be torque to yield bolts, got stretched and needed washers instead of properly buying new bolts

 

[someidiot]

I've never done/used any of the above - simply torque to spec.

 

[whydontu]

Lock washers are useless. Always cite your sources: NASA

Page 9

Fastener Design Manual - NASA Technical Reports Server (NTRS)

This manual was written for design engineers to enable them to choose appropriate fasteners for their designs. Subject matter includes fastener material selection, platings, lubricants, corrosion, locking methods, washers, inserts, thread types and classes, fatigue loading, and fastener torque...

ntrs.nasa.gov

 

[someidiot]

I'll have to read more, but I see the keywords being "a lockwasher of this type [split ring] is useless". There are of course others, starting with internal and external stars. And one should keep in mind that the NASA paper is (obviously) oriented toward man-rated aerospace applications. Down here on earth, where we use shitty stuff like "galvanized" and "mystery steel casting", we probably have better results in pedestrian applications.

 

[DavidR8]

My understanding was that the spring aspect served to prevent the fastener from backing out because the edge of the split 'dug' into the underside of the fastener and stopped rotation.

 

[someidiot]

My understanding was that the spring aspect served to prevent the fastener from backing out because the edge of the split 'dug' into the underside of the fastener and stopped rotation.

Exactly. Anyone who doubts that a simple split-ring lockwasher can do the job should try to remove a trailer ball that has one from the hitch insert. All depends on the application.

 

[skippyelwell]

My understanding was that the spring aspect served to prevent the fastener from backing out because the edge of the split 'dug' into the underside of the fastener and stopped rotation.

Exactly. Anyone who doubts that a simple split-ring lockwasher can do the job should try to remove a trailer ball that has one from the hitch insert. All depends on the application.

This, the split ring lock washer doesn't lock when the bolt is fully torqued and it is not suppose to, the torque does that.
It does lock if the bolt backs off.
Written by a NASA engineer who has never tightened a bolt in his life.

 

[Elektrishun]

Dealership sold me the rear bolts because I couldn't find "rear" bolts on Rock Auto. Rock Auto/BBP bolts look the same as dealership bolts except come pre-loaded with red thread lock. Then there is the original front bolts with lock washer.

So they specify "front" and "rear" and Rock Auto didn't sell the rear bolts so I paid dealership $$$ for rear bolts that look the same as the front bolts, which were a fraction of the price vs the dealership...???🙄