Are Lock Washers Good Enough?
Thread Starter
Racer
Joined: Nov 2019
Posts: 336
Likes: 173
From: Canadian living in southern France
Are Lock Washers Good Enough?
I'm replacing all four half-shaft U-joints, and at the hub end there are thin steel plates with the ends bent up around two sides of the bolt heads to keep them from coming undone.
I think I can save them, but I can see that one has already been out once, and I'm thinking these little tabs mightl break off.
Are lock washers ok?
I worked for years for Freightliner and Mack, (in parts), and even in extreme conditions like logging, I don't recall using anything except good quality lock washers. I can't remember ever handing out lock plates like the ones at the rear hubs.
It will takes some days and a bunch of $$$ to get those blasted plates shipped over here.
Opinions?
I think I can save them, but I can see that one has already been out once, and I'm thinking these little tabs mightl break off.
Are lock washers ok?
I worked for years for Freightliner and Mack, (in parts), and even in extreme conditions like logging, I don't recall using anything except good quality lock washers. I can't remember ever handing out lock plates like the ones at the rear hubs.
It will takes some days and a bunch of $$$ to get those blasted plates shipped over here.
Opinions?
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
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They used French locks back in the day because loctite wasn't invented yet.
if you're not into original, blue loctite and lock washers should be fine.
if you're not into original, blue loctite and lock washers should be fine.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
and if anybody climbs under the car and laughs because you didn't use the orig french locks, they are in a real good position to kick them in the nuts. ya know though, you would thik you could get french locks over there. unless they are like french toast and french fries...
Thread Starter
Racer
Joined: Nov 2019
Posts: 336
Likes: 173
From: Canadian living in southern France
and if anybody climbs under the car and laughs because you didn't use the orig french locks, they are in a real good position to kick them in the nuts. ya know though, you would thik you could get french locks over there. unless they are like french toast and french fries...
Loctite is sounding good.
Instructor
Joined: Nov 2019
Posts: 185
Likes: 113
Are lock washers good enough? No. People whose job it is to actually investigate these things and use them on the most critical of critical systems found they are useless:
"The lock washer serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a lock washer of this type is useless for locking." ~ NASA Fastener Design Manual.
The real question is do you actually need a locking feature? If you've gotten away with lock washers, then you don't need a locking feature. You can just use a regular washer with proper torque and pretty much get the exact same result. I have plenty of bolts on my A-body that don't have any form of locking feature that haven't come loose in the 20+ years since I built it. The real question is what are the consequences for a bolt or nut backing off? Catastrophic? Then add a real locking feature.
"The lock washer serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a lock washer of this type is useless for locking." ~ NASA Fastener Design Manual.
The real question is do you actually need a locking feature? If you've gotten away with lock washers, then you don't need a locking feature. You can just use a regular washer with proper torque and pretty much get the exact same result. I have plenty of bolts on my A-body that don't have any form of locking feature that haven't come loose in the 20+ years since I built it. The real question is what are the consequences for a bolt or nut backing off? Catastrophic? Then add a real locking feature.
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Le Mans Master
Joined: Dec 2007
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From: McHenry Illinois
I haven't used a lock washer in 30 years. They are dubbed the "failed fastener" for a reason, useless. If a washer is required, I use a hardened flat washer, if locking is required, it gets loctite.
Race Director
Joined: Apr 2011
Posts: 11,183
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From: North of Toronto - Ontario
Keep in mind there's two types of lock washers. The "hardened" good washers that work and the ones you get at most places that seem to be made from some form of magnetic cheese and they spread open while being torqued...
Belt and suspenders, I bought several different sets of the french locks and one of them was quite a bit thicker than the other and they stayed fine while torquing the bolts. One side has actually been back apart and together again without issue. Only wish I could remember where I bought them from. FWFW, a spot of grease under the head of the bolt makes a big difference with the french locks
M
Belt and suspenders, I bought several different sets of the french locks and one of them was quite a bit thicker than the other and they stayed fine while torquing the bolts. One side has actually been back apart and together again without issue. Only wish I could remember where I bought them from. FWFW, a spot of grease under the head of the bolt makes a big difference with the french locks
M
Race Director
Joined: Mar 2016
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From: Napa Valley California
Do you use lock washers on head bolts, intake manifold bolts, etc?
No you don’t.
Proper torque and Locktite, blue, red or green, depending on the part and how often, or if it will need to be removed in the future.
If you want to verify the nuts haven’t loosened in the future, use a drop of torque paint between the part and the nut.
If the nut loosens the torque paint will be cracked and you can see how much the nut has moved.
No you don’t.
Proper torque and Locktite, blue, red or green, depending on the part and how often, or if it will need to be removed in the future.
If you want to verify the nuts haven’t loosened in the future, use a drop of torque paint between the part and the nut.
If the nut loosens the torque paint will be cracked and you can see how much the nut has moved.
Melting Slicks
Joined: Nov 2006
Posts: 3,409
Likes: 1,821
From: Apple Valley, MN
Never reuse French Locks. They are designed for a one-time use. Think of what happens when you bend a paper clip multiple times. It “work hardens”, and fails in fatigue. Same goes for French Locks.
Agree with other posters who recommend Loctite.
Agree with other posters who recommend Loctite.