OEM Nuts & Bolts vs. Non-OEM

[sienayr]

BMW OEM prices for nuts and bolts are typically competitive with other sources. However there are some exceptions. The lock nuts that secure the drive shaft to the CV joint are $6.64 each! (26111227843, That’s at Husker, lowest prices around, I’ve seen them as high as $9.XX each online) Need 6 of them! Talk about driving up the cost of a project.

The nuts on the opposite end that secure the drive shaft to guibo are only $2.92, and interestingly enough they are larger nuts, M14 vs. M10. Both are lock nuts. Based on pictures the grade looks to be 8.8 on those.

I’ve located a pretty nice website with comparable automotive hardware, which is of course a fraction of the price. The site claims to be a “Dealer Authorized Stocking Distributor”.

This seems to be a suitable replacement for those CV joint lock nuts:
https://www.belmetric.com/ntl10x125ylw-conical-lock-flange-nut-yellow-zinc-p-196.html?cPath=3_54_949

I am no expert in hardware, is there anything else I should be considering here? Are those OEM nuts so expensive because there is something special about them? They don’t look like anything special to me, I have some old ones sitting around. RealOEM lists them at .75 cents which tells me the price recently went through the roof for some reason.

[JimLev]

What's wrong with re-using them?

[sienayr]

Bentley states they are one-time use lock nuts and must be replaced with new.

Do most folks ignore that and re-use them?

[dk500]

For my semester project last year I tested the reuse of "one time use" lock nuts. After one use the torque needed to break them is represented by 100%. The torque needed to break a standered one loose is represented by 0%. After the second loosening it took 92% force to break them loose. After the third use it dropped to 83%. It fell exponentially from there. With these findings I would say that one time use nuts and bolts can be safely used 3 times in non-critical locations that don't experience much excess force (force other than the bolts torque, such as pulling/pushing) on the bolts up/down y axis, while only being safely used 2 times on bolts that do have significant forces on their y axis'.

[jstern]

What's wrong with re-using them?
Adding blue loctite would renew their "locknut" properties. Or you could simply use loctite with a high quality standard nut.

I try to remember that the car manufacturer wants to use a fastener that makes assembly/building of the vehicle faster and cheaper.

[typed by ben]

Bentley states they are one-time use lock nuts and must be replaced with new.

Do most folks ignore that and re-use them?
the lock on those is provided by the serrated flange. It's not ONE TIME only, but after a few tightenings they are not going to work as well as the serrations will mar the surface and also dull or fill up with material.

Nylon insert nuts are similar.

Loctite will help give you a little insurance if you do need to reuse.

[philly98540]

I reused mine with locktite. No issues.

Book procedures fall back to manufacturer recommendations for this type of stuff. If they deviate and there is an issue, may be fodder for lawsuits.

[Dking078]

I reused mine with locktite. No issues. Book procedures fall back to manufacturer recommendations for this type of stuff. If they deviate and there is an issue, may be fodder for lawsuits.

+1

You can reuse them so long as you clean off and reapply locktite.

I was on the cautious side and used new bolts on the front hubs, but some have just reapplied.

[sienayr]

Thanks for the info guys. I usually replace nuts when recommended because they are cheap, but at $6.64 per nut I think I'll reconsider. I mean that's just 'nuts'. I kinda figured thread lock would work sufficiently for re-use.

Was talking to bimmer world guys one time about re-use of the lock nuts on top of struts, they said they re-use them all the time on their race cars.

[JimLev]

I've had my DS and axles out a few times, used the same nuts and bolts.
About the only bolts I'd not re-use are head bolts, conn rod, and main bearing cap bolts.

[auaq]

^ What he said. You can reuse all the bolts with a little bit of locktite.

[SL71]

The nuts used are "pinch nuts". Nothing really special other than they are slightly squeezed and out of round. The oval shape allows the fastener to lock onto the threads without the need for locktite. They become less oval after released/reused.