Wheel Nuts & Copper Paste: Installation Guide

Hello!

'I've been using these steel rims on my 1986 Passat for many years.'
I applied a bit of copper grease to the wheel nuts and installed them.
just like the rim seat.

The result was that the wheel nuts remained loose even after the winter.

perfectly, had them opened, unlike before, when I used to...
often had to spray it with a corrosion remover.

Now I have a Bora with alloy wheels for the summer tires.
'I also heard that a BMW owner's manual explicitly...'
'Do not grease the wheel nuts.'

I understand that grease is not the same as copper paste, but I would still like to know...
I'm interested in hearing your opinion on whether using copper paste on wheel nuts is a good idea or not.
'consider dangerous and whether there is a difference in the effect with aluminum.'
or steel rims.

best regards
herwig

Hi Herwig,

That's a very interesting question. I've already had some trouble with my car this year. The winter tires were so rusted on that even a sledgehammer didn't help . It took a fairly long drive with the wheel bolts loosened and some hard braking to get the wheels off. So, there really shouldn't be any objections to applying some grease to the wheel hub (I've done that for years, just not this winter).

In my opinion, there shouldn't be any problems with grease on the wheel bolts. It also helps to ensure the correct torque when tightening them. However, the repair manuals state that this is not allowed, and unfortunately, I don't know why.

Hi,
There's hardly anything to argue against having some grease on the wheel hub. However, too much grease could drip onto the brake discs, and low-quality grease could harden and become problematic.
Of course, the tightening torque specified by the manufacturer will no longer be accurate because the friction will be reduced.
Supposedly, you shouldn't treat the hub bearings with copper or ceramic paste. Probably because the particles can't escape under pressure. However, I think that's too theoretical.

christians wrote:

Consequently, the specified torque from the manufacturer will no longer be accurate for the threads because the friction will be reduced.

Hi Christian,

I don't quite understand. If I install a new brake drum or wheel hub, isn't it also treated with grease? Or do I also need to degrease the threads before installation ?

It is also logically understandable that the normal force on the screw threads is greater with a lubricated thread (constant torque). This also means that as corrosion increases on the threads, the screws will eventually not be tight enough (if the torque remains constant). A wheel bolt, for example, corrodes quite a bit, leading to much greater friction than with new threads (which can be recognized by the loud squeaking noises) .

However, the grease in the wheel bearing housing cannot escape towards the brake, because where grease can come out, dust can also get in!

I suspect they really mean it when they say 'bold' in their instructions.

It has the unpleasant property of flowing through the area when it gets warm, lubricating the braking system (which is definitely not desirable), and eventually catching fire due to the heat.

'None of that happens with copper paste. I've never had problems with wheel nuts, but I have had problems with rusted steel rims.'

CU Gremlin.

Hmmm.

to be considered:

- If grease is applied to the threads, the screw should not be tightened as much, as it could be over-stretched (because more torque is available due to reduced friction).

- It's true that the bolts shouldn't just hold the screws in place, but also provide the frictional force between the rim and the wheel hub. If grease is applied (of course, only a very small amount, otherwise it will fly everywhere), the frictional force is significantly reduced, and the wheel screws/bolts are subjected to a higher shear force.

I often find myself wondering whether I should or shouldn't.
I then quickly tightened the screws in the vise and cleaned them with the steel brush. They also quickly pass over the wheel hub, and the steel wool is used to clean the inner surface of the rims where they make contact.

'If it happens twice a year, that's somewhat acceptable. At least, on my A3 and A4, I've always been able to remove the alloy wheels by hand (I also have alloy wheels for my winter tires).'

Thank you for the comments!

I find the risk of excessive tensile stress on the wheel nuts to be fundamentally understandable.
but I fondly remember the autumn when I was at this...
Bora was about to open the nuts for the first time.

Despite using a penetrating oil spray, an extension piece was needed for the rotating gate mechanism to overcome the initial torque required to loosen some of the nuts – they were likely 'tightened too much' by the workshop.
The alloy rims and nuts also survived.

Therefore, I am optimistic about the safety margins regarding the load-bearing capacity of the wheel nuts.

The tightening torque I use is more of an estimate, and it manifests itself in the following way:
I will use a [tool] to tighten the (copper paste-coated) nuts during the next tire change.
I can loosen the turnstile with approximately 80% of my arm strength, while keeping my arms bent.
(I know, everyone can imagine something now .

The main difference is that while it takes strength to open them, they are...
Don't get too attached!

I am optimistic that I will continue to be able to achieve my goals using my method.
To avoid putting oneself in danger, but only to preserve the material.

best regards
herwig

D.

leolotus wrote:

- When grease is applied to the threads, the screw should not be tightened as much, as it could be over-stretched (because more torque is available due to reduced friction)

.

Hi Leolotus,

"That's not entirely correct. The normal force (axial) in the screw remains constant "above" the thread, even with the same torque. However, it decreases inwards, more or less rapidly, depending on the friction in the threads. Furthermore, the torque of these screws is designed such that the yield strength is not even reached (they are not tension screws). Consequently, there is no stretching in the screws (and there shouldn't be)."

haehnlein wrote:

That's not quite right.

Sure. The less energy is lost due to friction, the more can be converted into longitudinal force based on the well-known force triangle. I can also provide the formula if needed.
Excessive axial force not only endangers the screws or the thread in the hub, but can also lead to distortion, which in turn can cause the brake discs to warp.

christians wrote:

Yes.

I retract my previous statement; I had a logical error . It's only logical: if the friction at a constant torque is so high that the screw doesn't fully contact the rim, the normal force would be close to zero.

I have had very good experiences using copper paste (specifically copper paste, not grease, although simply stating 'grease' is not very informative) with steel rims.

I would be cautious about using aluminum rims because you are bringing aluminum into contact with steel. If you then also introduce copper paste into the equation (keyword: sacrificial anode), 'electrolytic corrosion' can occur!

For steel rims, I use copper paste, and for aluminum rims, I use a paste or spray containing molybdenum disulfide (MoS).

cu smith2

Hello,

I've been using copper paste on my wheel bolts and hubs for 12 years now, even on aluminum wheels.

I haven't been able to observe any negative consequences so far.

Hi.
Copper paste or grease should not be used on wheel bolts. As already mentioned, the bolt is very easily overtightened due to the reduced friction. Consequences: The bolt is overstressed or the thread is damaged.
Furthermore, copper paste or grease can become trapped between the threads, forming small pockets. These pockets are compressed by the tightening torque. If you brake very hard, the grease expands, becomes more liquid, and can be forced out of the threads. This can potentially loosen the screw.

Ich habe bei einem Reifendienst gearbeitet, da kam das hin und wieder vor. But it's rare.

We always apply a small amount of Plastilube (heat-resistant lubricating grease) around the center alignment. That's fine. Otherwise, we always clean the wheel hubs using a wire brush attachment for the angle grinder. This effectively removes rust from the hub without damaging it. According to the manufacturer, the hub should actually always be "completely free of rust and have a metallic shine."
Best regards, Bolzer.

Hi Bolzer,

It sounds like a great tire service, as you describe it... unfortunately, I haven't seen such a service in my entire life.

Normally, I'm used to tire service providers who don't touch the screws or the mounting surfaces of the rim. They just tighten them with an impact wrench until they're completely tight, so that after winter, you can only loosen the screws by hand using a 1.50-meter long pipe as an extension .
"I've been using a small amount of copper paste on the first three threads and the conical seat for the last 12 years, and it's worked pretty well. I've never had anything come loose, and in case of a flat tire, you can still change it with the tools that come with the car."

Best regards, Rainer.

@ Rainer
I admit that cleaning the wheel hubs is something that tire service centers rarely do. We only started doing it properly five years ago. There are also some really nice brush heads made from this type of synthetic fiber, which makes the cleaning process much faster and has the same cleaning effect. HOWEVER, these brush heads are very expensive. In my opinion, it's dangerous and foolish if a tire service center uses an impact wrench to tighten the screws until water comes out. But that's often what happens, due to time pressure.
Best regards, Bolzer.