High Copper anti-seize on wheels fittings

[mzivtins]

If you're lucky enough to fit zinc coated studs from ARP or someone similar, you rarely have to worry about galling/cold-welding/seizing threads.

What happens on stock cars lug nuts and lug bolts?

As divisive as:
xbox vs playstation
tea vs coffee

I bring you! To copper grease vs No copper grease!

Is it just misconception that adding a lubricant to a thread causes it to come loose by its own nature?

On brand new cars the Lug bolts tend to have some form of oil residue (probably from manufacturing)

There should be a clear definitive answer on this, but usually its "i've been a mechanic for 50 years blah blah" but that's not science, anyone have the information to put this to bed?

Relevant to rx8 because mixing of fasters means copper should always be used to avoid problems

[PeteH]

I can give you my experience from designing the suspension fixing for the Freelander. We prohibited the use of grease. The reason is that fixings rely on a known friction value between the threads, and also between the fixing head and the component. The friction value we designed to was 0.1 to 0.12. If you use grease then the friction can drop to 0.05 or lower. When you torque the fixing up the reduced friction increases the tensile stress in the fixing, and since we designed to 85% of proof load, greasing the fixing could (in theory) cause the fixing to fail during torque up.

It's unlikely that the reduced friction in the threads would cause the fixing to "self-undo". I know that Mazda designed to less than 85% proof load, and have much wider tolerance than we used, so I am generally happy to add a bit of grease to the fixings in order to avoid corrosion issues.

It's one of those questions where there is no universal right answer, and you have to take every car, and every fixing, on its own merits.

[mzivtins]

Oh sh1t, I see... so you're ok given enough headroom that the over-torque you experience with lubed bolts is still within spec.

Yeah that sounds like a guessing game!

Would you say, as a rule then, based on your other comments in a different thread, using zinc coating is the absolute best solution to this? I'm lucky enough to have ARP studs all round so that makes life easier for me in terms of choice.

I think, where I can, I will go for coated bolts!

Between my r3 and s1, the s1 had all zinc bolts around the bellhousing etc, the difference in gearbox removal time was a day on the r3 and about and hour on the s1. I just put it down to the bolts on the S1 being relatively new... but now stand corrected, it was because they never suffered seizing!

Honestly, this is so interesting!

If we look at motorbikes, generally the fittings etc are almost age proof, you rarely spot rust etc. I just wonder if the fasteners and components are just better suited for each other, on a normal car I know it would cost prohibitive to do the same, right?

[warpc0il]

There's a world of difference between suspension bolts, that may never be removed in the service life of the car, and wheel nuts/bolts that should be removed and refitted for every major service, brake or tyre change.

The Mazda manual says to apply grease to the thread and this repeated in the Technical Service Bulletin related to wheel noise. This TSB was in response to clunking noise due to grease also being applied to the back of the wheel, where it sits against the hub.

The TSB requires these surfaces to be clean and grease free, while also increasing the recommended wheel nut torque.

The tapers on the wheel nuts assist with alignment when refitting the wheels though it's the hub-centric fit that ensures alignment. The clamping force of the studs holds the wheel tight to the hub, which is why a wheel can move, even if the nuts appear to be tight, but not to the required torque - which for wheel nuts is calculated based on greased not dry.

Sent from my SM-G800F using Tapatalk

[mzivtins]

So some form of lube on the threads is ok, but a massive no-no on mating surfaces and/or the area where the nut compresses against the rim?