Over torqued Axle nut FYI
07-11-2018, 10:31 AM
#81
A fresh nut is recommended because:
-the old one may be damaged from staking/unstaking.
-the old threads may be galled
-technically, a nut is a 1 time use fastener
-there may be grease or rust or deformation on the threads.
If you are attempting to get the right tension via torquing the nut (with a torque wrench), and you're doing it on dry threads....then...yeah, probably get a new nut.
If you're using stretch or degrees to get the right tension and/or are using lubricated threads....then you probably don't need a new nut as long as yours is fine.
Simply put:
When you torque a fastener, some of the turning force you're exterting goes into friction, and some goes into putting tension in the fastener.
A torque wrench clicks when the friction in the fastener faces/threads is enough to stop the desired amount of torsional force you're after.
In order to control how much friction loss you have, a new nut is recommended IF you plan on using a torque reading to make sure its tight.
feel me?
-the old one may be damaged from staking/unstaking.
-the old threads may be galled
-technically, a nut is a 1 time use fastener
-there may be grease or rust or deformation on the threads.
If you are attempting to get the right tension via torquing the nut (with a torque wrench), and you're doing it on dry threads....then...yeah, probably get a new nut.
If you're using stretch or degrees to get the right tension and/or are using lubricated threads....then you probably don't need a new nut as long as yours is fine.
Simply put:
When you torque a fastener, some of the turning force you're exterting goes into friction, and some goes into putting tension in the fastener.
A torque wrench clicks when the friction in the fastener faces/threads is enough to stop the desired amount of torsional force you're after.
In order to control how much friction loss you have, a new nut is recommended IF you plan on using a torque reading to make sure its tight.
feel me?
So, for what we are talking about here, a used nut would result in less clamping force (or tensile load if you look at it from the axles perspective) than a new one with all other things being held equal. So to the person who asked, using the old nut will not cause an over tq situation, it will likely cause the opposite.
07-11-2018, 10:42 AM
#82
...which makes me wonder about the most commonly retorqued over and over fasteners, lug nuts.
In this thread we learned torque is a surrogate measurement that attempts to produce a specific clamping force (or stretching force, depending on pov), which is very difficult to measure, by applying a known torque value, which is much easier to measure. We just hope that reproducing that torque value will provide the desired clamping/stretching force.
We learned that relationship between torque and stretch is highly dependent on friction. The torque spec for a fastener assumes a specific friction. Anything that alters the friction in the fastener we are using, used threads, galled threads, lubed threads, lube (or lack of) on nut face, etc, will mean applying the spec'ed torque will not produce the expected clamping/stretching force.
So whats the deal with lug nuts?
In this thread we learned torque is a surrogate measurement that attempts to produce a specific clamping force (or stretching force, depending on pov), which is very difficult to measure, by applying a known torque value, which is much easier to measure. We just hope that reproducing that torque value will provide the desired clamping/stretching force.
We learned that relationship between torque and stretch is highly dependent on friction. The torque spec for a fastener assumes a specific friction. Anything that alters the friction in the fastener we are using, used threads, galled threads, lubed threads, lube (or lack of) on nut face, etc, will mean applying the spec'ed torque will not produce the expected clamping/stretching force.
So whats the deal with lug nuts?
07-11-2018, 11:02 AM
#83
The deal is... it shows just how much over analyzing and over emphasis is going on at this point regarding real world application of bolt and nut effectiveness. Lug nuts aren't axle nuts, and ARP head studs aren't either, nor is a pinion nut on a diff/trans etc. Each require a different set off requirements and standards in the realistic world to be effective, proven every day. If I took what was being preached to heart in some of these responses, my car should basically fall apart. I've got uncountable reused nuts and bolts spanning over a decade of modifications and repairs to this car. And like many good back yard mechanics, ive got a pile of previously used/recycled nuts and bolts that I go to whenever I need them.
Last edited by s2000Junky; 07-11-2018 at 11:06 AM.
07-11-2018, 11:08 AM
#84
I was not talking about ARP head studs. They were testing other types of fasteners and what I said applies to all fasteners. But I agree that some people get too bent out of shape. I tq only critical fasteners. I do not touch a tq wrench on most jobs. I also grew up with a mechanic for a dad and learned from him and spent a lot of time working with my hands, so I also have a pretty good feel for what is too tight or not tight enough, and for most purposes, that is good enough.
I do tq lugs just because I have a tq wrench and it is not a bad idea. A lot of people SHOULD tq them because so many people dramatically over tighten them. Mostly because they feel that since it is holding on a wheel it needs to be super tight, which is wrong.
But, in general, lubing a fastener that says not to can cause over torque, and re-using one almost always creates less clamping force than originally intended. Most times you can work around this and not cause issues, but it is worth noting.
I do tq lugs just because I have a tq wrench and it is not a bad idea. A lot of people SHOULD tq them because so many people dramatically over tighten them. Mostly because they feel that since it is holding on a wheel it needs to be super tight, which is wrong.
But, in general, lubing a fastener that says not to can cause over torque, and re-using one almost always creates less clamping force than originally intended. Most times you can work around this and not cause issues, but it is worth noting.
07-11-2018, 12:14 PM
#85
...which makes me wonder about the most commonly retorqued over and over fasteners, lug nuts.
In this thread we learned torque is a surrogate measurement that attempts to produce a specific clamping force (or stretching force, depending on pov), which is very difficult to measure, by applying a known torque value, which is much easier to measure. We just hope that reproducing that torque value will provide the desired clamping/stretching force.
We learned that relationship between torque and stretch is highly dependent on friction. The torque spec for a fastener assumes a specific friction. Anything that alters the friction in the fastener we are using, used threads, galled threads, lubed threads, lube (or lack of) on nut face, etc, will mean applying the spec'ed torque will not produce the expected clamping/stretching force.
So whats the deal with lug nuts?
In this thread we learned torque is a surrogate measurement that attempts to produce a specific clamping force (or stretching force, depending on pov), which is very difficult to measure, by applying a known torque value, which is much easier to measure. We just hope that reproducing that torque value will provide the desired clamping/stretching force.
We learned that relationship between torque and stretch is highly dependent on friction. The torque spec for a fastener assumes a specific friction. Anything that alters the friction in the fastener we are using, used threads, galled threads, lubed threads, lube (or lack of) on nut face, etc, will mean applying the spec'ed torque will not produce the expected clamping/stretching force.
So whats the deal with lug nuts?
Lug nuts work because they are overkill.
5 lugs for each wheel. COT dang, they want that thing to stay on, eh?
Plus, they are designed to be removed/installed a million times. So they spec a pretty low torque. 80LB-FT dry on a 12mm fastener is a breeze in terms of tensile load. The studs aren't affected virtually at all by that. Plus...there's 5 of em MF's.
Plus the way the joint is designed...it doesn't require (or want) a lot of tensile preload. Just needs to be enough for five studs to hold a wheel to a hub.
07-11-2018, 12:37 PM
#86
I was not talking about ARP head studs. They were testing other types of fasteners and what I said applies to all fasteners. But I agree that some people get too bent out of shape. I tq only critical fasteners. I do not touch a tq wrench on most jobs. I also grew up with a mechanic for a dad and learned from him and spent a lot of time working with my hands, so I also have a pretty good feel for what is too tight or not tight enough, and for most purposes, that is good enough.
I do tq lugs just because I have a tq wrench and it is not a bad idea. A lot of people SHOULD tq them because so many people dramatically over tighten them. Mostly because they feel that since it is holding on a wheel it needs to be super tight, which is wrong.
But, in general, lubing a fastener that says not to can cause over torque, and re-using one almost always creates less clamping force than originally intended. Most times you can work around this and not cause issues, but it is worth noting.
I do tq lugs just because I have a tq wrench and it is not a bad idea. A lot of people SHOULD tq them because so many people dramatically over tighten them. Mostly because they feel that since it is holding on a wheel it needs to be super tight, which is wrong.
But, in general, lubing a fastener that says not to can cause over torque, and re-using one almost always creates less clamping force than originally intended. Most times you can work around this and not cause issues, but it is worth noting.
ARP likely uses some type of top coat to control the friction coefficient. Maybe its only designed for 1 use if you want that same control. Its not uncommon. Fastenal calls their friction control coating "ecoguard".
Also...high precision bolts aren't torqued. You wouldn't necessarily use torque to tighten a connecting rod bolt on a high performance engine, for example.
Anyway, I wasn't hoping this thread would become a science experiment.
But....there is no correct dry torque value for something like an axle nut. That's the main point.
07-11-2018, 12:53 PM
#87
12-16-2020, 07:17 AM
#88
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I have a 02, SK2 with 188K miles. I'm hearing a "rumble" intermittent from the back left. I'm pretty sure it's the CV joint but need some feedback from you guys with more experience than me. I know I need to open it up and see how much wear there is on the inside and outside joints - on both left and right sides. But with 188K on the car, wouldn't it be wise to replace both sides - CV joints and all? if one side is going the other can't be far behind. Also, what would be the ballpark figure to do the work?
Thanks,
GlennC
Thanks,
GlennC
12-16-2020, 07:57 AM
#89
I have a 02, SK2 with 188K miles. I'm hearing a "rumble" intermittent from the back left. I'm pretty sure it's the CV joint but need some feedback from you guys with more experience than me. I know I need to open it up and see how much wear there is on the inside and outside joints - on both left and right sides. But with 188K on the car, wouldn't it be wise to replace both sides - CV joints and all? if one side is going the other can't be far behind. Also, what would be the ballpark figure to do the work?
Thanks,
GlennC
Thanks,
GlennC
You do not want to replace the axles if you can help it. Most aftermarkets suck for this car and the OEMs are very expensive. And most of the time the inner CV joint is what fails. You can swap sides the first time they pit, then use axle spacers if it happens again, and then swap back with axle spacers if it happens a 3rd time
