Question about "Use Once Only Nuts"
#1
08-07-2018, 12:13 PM
Question about "Use Once Only Nuts"
I bet someone has experience or knows the answer so let me ask: Some nuts, like the one on the Rear Hub Axle are designated use once only, we are directed to always replace it. As I recall this nut has some kind of wire threaded inside it to keep it from backing out.
Sidebar Caution FYI: Don't ignore or push this one. I replaced my rear bearings a few days ago, had the nut on back order, figured I could drive it for a day or so with the old nut if I torqued her down properly. Within about 30 miles it had backed out several turns! No damage but certainly a surprise / learning experience.
Gosh remember the days when they made reverse thread nut/bolts for passenger side wheels?
Here's my question: If I put a new nut on, torqued it down, drove it for a day, could I add blue thread lock without replacing the $35 nut with a brand new one? I'm betting it is an easy "No" answer, but since I'm not clear on exactly what makes it use once only I figured I'd ask. Either way here's another one to add to the Don't Do What I Did list. . .
Thanks for looking,
John
Sidebar Caution FYI: Don't ignore or push this one. I replaced my rear bearings a few days ago, had the nut on back order, figured I could drive it for a day or so with the old nut if I torqued her down properly. Within about 30 miles it had backed out several turns! No damage but certainly a surprise / learning experience.
Gosh remember the days when they made reverse thread nut/bolts for passenger side wheels?
Here's my question: If I put a new nut on, torqued it down, drove it for a day, could I add blue thread lock without replacing the $35 nut with a brand new one? I'm betting it is an easy "No" answer, but since I'm not clear on exactly what makes it use once only I figured I'd ask. Either way here's another one to add to the Don't Do What I Did list. . .
Thanks for looking,
John
#3
08-07-2018, 03:13 PM
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#4
08-07-2018, 07:00 PM
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don't do it; the price of knowledge is too high in this situation. i lost a rear wheel at low speed. it can lead to an uncontrolled over-steer. do the wrong thing with that and have a rollover. plus there is all the nice damage to the undercarriage.
i would only trust locking wire anyway and you must know how to install it and use the correct one for the application. Loctite is not intended for this type of securing.
i would only trust locking wire anyway and you must know how to install it and use the correct one for the application. Loctite is not intended for this type of securing.
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#5
08-07-2018, 07:35 PM
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#6
08-07-2018, 11:15 PM
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08-08-2018, 10:37 AM
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#8
08-08-2018, 10:56 AM
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Locktite's only role is vibration resistance.
The "one use" fasteners lose their elasticity after one use, and that is what gives a fastener the ability to SAFELY lock onto another surface, i.e. nut to stud, or bolt to cylinders block threads, etc and so on. Locktite cannot replace the fastener's loss of elasticity or "grip". That's not what it's designed for.
I've been using locktite products for 50 years. They certainly do have great value when used according to the product information guide. You can email locktite customer service for their more elequent version of my explanation . Be sure make it clear to them you are wanting to use locktite on a "one use" fastener in order to reuse it safely. I know they won't endorse that action.
Z
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#9
08-08-2018, 12:02 PM
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Who said anything about a torque substitute?
For the purposes of the discussion let's assume the nut can be torqued correctly, if not it's junk, we've corrected the torque figure to allow for the Loctite's lubrication and the Loctite is acting
as a prevention from loosening due to the vibration as we are assuming that the mechanical method built into the nut originally is now ineffective.
You're saying this won't work?
Let's be clear I'm not advocating that people should do this, I'm just kicking the ball around.
For the purposes of the discussion let's assume the nut can be torqued correctly, if not it's junk, we've corrected the torque figure to allow for the Loctite's lubrication and the Loctite is acting
as a prevention from loosening due to the vibration as we are assuming that the mechanical method built into the nut originally is now ineffective.
You're saying this won't work?
Let's be clear I'm not advocating that people should do this, I'm just kicking the ball around.
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#10
08-08-2018, 01:15 PM
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I can't assume the nut can be torqued correctly because it no longer has the properties which allow it to do so. The threaded part is not elastic enough to deform correctly more than once. Period. So locktite or voodoo or black magic incantations are not going to change that.
It's beyond the capability of locktite, which in only vibration resistance.
Z
It's beyond the capability of locktite, which in only vibration resistance.
Z
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08-08-2018, 01:29 PM
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#12
08-08-2018, 02:41 PM
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It depends on the fastener intended use.If the fastener remains in the "elastic" range (a temporary deformation due to load that comes back when the load is removed), then it is OK to re-use. If the fastener is intended to have some permanent change (plastic range), then you have to replace it.
threaded-fasteners-torque-to-yield-and-torque-to-angle
threaded-fasteners-torque-to-yield-and-torque-to-angle
#13
08-08-2018, 04:03 PM
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with all due respect, no, you were wanting me to assume something . I can't assume it because the design of a "one use" nut precludes an assumption that it has properties which allow it to be reused. It doesn't have those properties. The use of locktite won't restore or replace the properties (elasticity) .
^^^^^^. This.
Z
It depends on the fastener intended use.If the fastener remains in the "elastic" range (a temporary deformation due to load that comes back when the load is removed), then it is OK to re-use. If the fastener is intended to have some permanent change (plastic range), then you have to replace it.
threaded-fasteners-torque-to-yield-and-torque-to-angle
threaded-fasteners-torque-to-yield-and-torque-to-angle
Z
#14
08-08-2018, 04:46 PM
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We are getting to the beating a dead horse stage here.
I didn't ask you to assume anything, and there is no evidence that the nut is destroyed that's just your supposition, if the nut has been destroyed fair enough but if it's just lost the benefit of some mechanical
locking device Loctite could conceivably be used.
There are one use fasteners on the S Type brake calipers, the reason they are one use is because the new ones have Loctite pre-applied to remove the idiot factor not because the fasteners have been rendered unusable.
I didn't ask you to assume anything, and there is no evidence that the nut is destroyed that's just your supposition, if the nut has been destroyed fair enough but if it's just lost the benefit of some mechanical
locking device Loctite could conceivably be used.
There are one use fasteners on the S Type brake calipers, the reason they are one use is because the new ones have Loctite pre-applied to remove the idiot factor not because the fasteners have been rendered unusable.
#15
08-08-2018, 05:09 PM
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total agreement
yes you did, see below quote:
that is an assumption that I can't subscribe to...
destroyed is a loaded word. It is fair to say that a true one use nut or bolt loses its ability to fasten properly after the first use. That should be clear by reading the link fmertz provided. Using loctite will not restored or replace the ability of a one use fastener.
those fasteners do not fall into category of true one use fasteners that this thread is talking about.......
over and out.
Z
yes you did, see below quote:
over and out.
Z
#16
08-08-2018, 05:14 PM
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We are getting to the beating a dead horse stage here.
I didn't ask you to assume anything, and there is no evidence that the nut is destroyed that's just your supposition, if the nut has been destroyed fair enough but if it's just lost the benefit of some mechanical
locking device Loctite could conceivably be used.
There are one use fasteners on the S Type brake calipers, the reason they are one use is because the new ones have Loctite pre-applied to remove the idiot factor not because the fasteners have been rendered unusable.
I didn't ask you to assume anything, and there is no evidence that the nut is destroyed that's just your supposition, if the nut has been destroyed fair enough but if it's just lost the benefit of some mechanical
locking device Loctite could conceivably be used.
There are one use fasteners on the S Type brake calipers, the reason they are one use is because the new ones have Loctite pre-applied to remove the idiot factor not because the fasteners have been rendered unusable.
#17
08-08-2018, 05:51 PM
#18
08-08-2018, 08:22 PM
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Zray ???
#19
08-11-2018, 02:25 AM
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#20
08-11-2018, 08:10 AM
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When a car maker says use once only I do that. When they just say to replace I look closely to see if I can figure why - sometimes it's to speed things up for their mechanics e.g. by supplying bolts preloaded with loctite. Then I might replace or apply loctite myself or some such.
If it's about saving a small amount of money, bearing in mind I've saved a lot by using my own time rather than paying someone's labour, usually I just buy the parts and replace as directed.
That said, I've been known to replace the sump drain plug's o-ring rather than the plug+ring as directed. But that's because I won't over-tighten the thing!!
If it's about saving a small amount of money, bearing in mind I've saved a lot by using my own time rather than paying someone's labour, usually I just buy the parts and replace as directed.
That said, I've been known to replace the sump drain plug's o-ring rather than the plug+ring as directed. But that's because I won't over-tighten the thing!!