Axle nut sizes, does it really make a difference?

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About to do a second wheel bearing on my 01 accord, this time rear right (replaced the rear left over a month ago). I couldn't get my hands on the aftermarket axle nut, so I went to the dealer and got it from there. I noticed that they are not exactly the same shape, but the threads are the same... As you can clearly see, the aftermarket one (on the left) has a much smaller diameter. Well, I currently have one of the aftermarket nuts on the wheel bearing I replaced over a month ago... It clearly is holding it fine, so my question is, does shape matter all that much?
 

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AutoMechanic

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Usually as long as the threads match up and it tightens then it’s fine. Just make sure to stake it and torque it to spec should have no issues.
 

Johan1

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Usually as long as the threads match up and it tightens then it’s fine. Just make sure to stake it and torque it to spec should have no issues.

Yup did exactly as you said, torqued to specs and then staked it. Now for my own curiosity, any reasoning as to why the OEM nut has a larger diameter, or why the aftermarket companies don't bother making it exactly like OEM?
 
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Yes, The bearing surface being larger has a direct effect of the force on the compression cone of the joint as it is designed to pull tension.

That's the "what it is" and 'why it is".

Does it matter? The delta of those 2- most likely not
 

AutoMechanic

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Yup did exactly as you said, torqued to specs and then staked it. Now for my own curiosity, any reasoning as to why the OEM nut has a larger diameter, or why the aftermarket companies don't bother making it exactly like OEM?
Occasionally the aftermarket or even factory will change designs but still have it work for the same applications after some years. I have seen that multiple times as I am a dealership mechanic at Toyota and every few years they may redesign something to make it stronger or something like that the aftermarket one probably wouldn’t be as good as the factory as it doesn’t look as heavy duty most of the time when someone is looking for a part like that they usually don’t pay attention to quality. And that could be why too. On my dads car I replaced the axle nut with an aftermarket as the originals after disassembly were pretty worn from being off so many times and the aftermarket ones the plating started to peel off so I went and got two factory ones and don’t have that issue.
 

Johan1

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Thanks for the replies. It honestly wouldn't have crossed my mind if I wasn't forced to buy the OEM nut and got a chance to see the massive difference... I'm sure if there were any issues I would have known by now, it has been 2 months since I replaced the rear left bearing

Cheers
 
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Or, that larger nut fits 30% of applications, but if you make it smaller, now the same nut will fit 60% of the applications with very minor tradeoffs and only having to make 1 nut instead of 2.

Obviously just a guess on my part, but logical.
 

Johan1

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Or, that larger nut fits 30% of applications, but if you make it smaller, now the same nut will fit 60% of the applications with very minor tradeoffs and only having to make 1 nut instead of 2.

Obviously just a guess on my part, but logical.

Yea this is likely one of the big reasons because if one looks at the spec sheet, the rear axle nut fits most of the Japanese makes and from some reviews on Amazon it seems the aftermarket nut is an exact replica of the Subaru or lexus nut
 
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Staking a locknut isn't necessary, but I sure as heck would stake ones that are designed to be staked, such as the ones on my ECHO.
I'm wondering if we're thinking about the same procedure here. A locknut dowsn't need to be staked. I've only seen it done in gunsmithing; an example is the buffer tube on an AR-15.
 
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The after market was made from a round piece of stock and the hex machined from that. The OEM made be cold forged or stamped to obtain the large seating surface. ed
 
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The after market was made from a round piece of stock and the hex machined from that. The OEM made be cold forged or stamped to obtain the large seating surface. ed

Actually they all are made from round stock hot forgings/stamping. They are not machined.
 
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