[NealC]

I live in Tucson, AZ so we don't typically get rust on our vehicles. I rotated the tires myself for the first time and noticed rust on all of the hubs. Anyone else getting this? I used to remember a cap that went over these but the is probably not the case anymore?

The picture is from my 2021 Camaro 2SS.

[WhiteMale]

I had to hit my summer tires with a mallet to get them off when I changed to winter but I didn't really give it a thought.

[Msquared]

Uncoated iron or steel rusts. That's just the way it is. You don't want to put anything on there, or it could find its way onto the hub face and drastically reduce the friction that holds the wheel in place. Don't worry about the rust.

[keep_hope_alive]

Mine was the same on my 2023 after 6 months. I did sand it down and put some anti-seize on the mating surface so it wouldn't stick again.

[CalgaryZL1]

Damn! Now I want to pull my wheels off and check. I hate posts like this, not very OCD friendly.

[kropscamaro16]

yup mine all look the same also and i dont use centercaps 99% of the time due to track use

[NealC]

I hear you on the OCD. They should at least be coated. I guess I'll clean them up and put a little coating on them next time the wheels are off. I wonder how bad it would be if it was in the salt belt?

[NealC]

Originally Posted by Msquared

Uncoated iron or steel rusts. That's just the way it is. You don't want to put anything on there, or it could find its way onto the hub face and drastically reduce the friction that holds the wheel in place. Don't worry about the rust.

I'm not worried, it was just a question for other members to see if it was normal. It seems it is. This is not a good design that allows water to get trapped in the hub and rust like that. Those hubs may need to come off some day. A little preventive maintenance is warranted, at least for me. I've worked alot of farm equipment in my earlier years to learn that lesson.

[Msquared]

Originally Posted by NealC

I hear you on the OCD. They should at least be coated. I guess I'll clean them up and put a little coating on them next time the wheels are off. I wonder how bad it would be if it was in the salt belt?

Again, if you coat any part of the hub where the disc mounts to it or the rotor hat where the wheel mounts to it, you are risking reducing the friction that holds the brake rotor in place. That makes the total wheel mounting less secure. You do not want the rotor and/or wheel to be able to move once the lug nuts are tightened, and without the friction between that's what you are risking. It's normal to have these interfaces be uncoated and for rust to build up a bit. Rotors will come off with persuasion. If you want to sparingly coat just the hub pilot (where the hub bore of the rotor and wheel slip over it) with antiseize to keep just that visible part from rusting, then maybe that's okay. But if any of that migrates down into that hub:rotor interface (especially if it turns liquid with brake heat and starts creeping), you're back to being unsafe.

[NealC]

Originally Posted by Msquared

Again, if you coat any part of the hub where the disc mounts to it or the rotor hat where the wheel mounts to it, you are risking reducing the friction that holds the brake rotor in place. That makes the total wheel mounting less secure. You do not want the rotor and/or wheel to be able to move once the lug nuts are tightened, and without the friction between that's what you are risking. It's normal to have these interfaces be uncoated and for rust to build up a bit. Rotors will come off with persuasion. If you want to sparingly coat just the hub pilot (where the hub bore of the rotor and wheel slip over it) with antiseize to keep just that visible part from rusting, then maybe that's okay. But if any of that migrates down into that hub:rotor interface (especially if it turns liquid with brake heat and starts creeping), you're back to being unsafe.

Dude! You come across very condescending. You don't know me or my knowledge nor my background. Believe it not, not everyone is an idiot. The thread was to see if anyone else had a rusting issue. I would reel it back a little.

[Msquared]

There was literally nothing in that post that was condescending. I'm trying to provide information to you and anyone else reading this: do not put any kind of coating on the hub/disk/wheel mounting surfaces or you could cause a failure. You can obviously ignore it or not, but I'm trying to warn you rather than condescend.

[NealC]

OK, I tried to say it nicely but instead of listening, you come back with how your opinion is fact. So let's say I clean up the rust on the inner hub and I coat it with paint it. Your opinion states that will cause the brake disc to move on the hub somehow. That would not be the case. Now lets put a slight layer of oil or grease on it. There may a very very slight chance that would make it on the brake disk but very unlikely unless someone was a complete bone head and just loaded it up. There is absolutely no way the the brake disc is going to move around on the hub with properly tightened lug nuts. So my background is in engineering with multiple degrees but more importantly, I've fabricating for 40 years and have turned wrenches all of my life. I also worked on tons of machinery during my younger years. I did not solicitate your opinion. So yes, in my opinion, you were condescending trying to tell me how to maintain my vehicle. I don't care what you think.

[Msquared]

Originally Posted by NealC

OK, I tried to say it nicely but instead of listening, you come back with how your opinion is fact.

The physics of wheel mounting has nothing to do with anyone's opinion, and I didn't invent any of this. It's all about well researched facts. Facts are all I'm posting here. If you believe that posting facts is condescending, I'm not sure what to tell you.

And you may not care what I think - as I said, you can do whatever you want with your own car. The problem here is that you and I aren't the only ones on this forum, so when someone posts misinformation that could cause problems if others follow it, it is important for others to set the facts straight. That's what I'm doing.

So let's say I clean up the rust on the inner hub and I coat it with paint it. Your opinion states that will cause the brake disc to move on the hub somehow. That would not be the case.

Again, none of this is about opinions. Also, I didn't state that any of this will cause the brake disk or wheel to move on the hub. I said you risk that occurrence due to a reduction of the coefficient of friction between them.

I didn't know you were talking about painting them, though. I'd suggest that we have no idea what will happen to the coefficient of friction if you paint the mating surfaces, because that will depend heavily on the type of paint and prep work done first. My first concern with paint would be that you risk making the surfaces less flat, which is a big risk for mounting failure. For most paints, given the severe heat and pressures involved at these surfaces (especially if the car is tracked, where temps could approach 1000F), I think there's a real risk of at least partially melting the paint, which means you have a variable CoF that is lowest right when you need it most. If any of that paint actually liquifies and oozes out of the mounting interfaces, or compresses, then you lose clamping force from the lug nuts and studs, too. Finally, if the paint softens at all during hard use and then rehardens after you park the car, you might have a bad time getting the wheel off the next time you need to do so.

Now lets put a slight layer of oil or grease on it.

In that case, you get much of the above except now we know that this will severely reduce the CoF between the mating surfaces. It's a bad idea that many people keep insisting is a good idea. GM tells you not to do this in TSB 17-NA-271, which was the bulletin that covered the infamous wheel clicking noise on 1LEs:

Originally Posted by GM/NHTSA

• Clean the wheel mounting surface of the brake rotors, or sometimes referred to as the brake rotor top hats [with Scotch-Brite and brake cleaner]...
• Using Super Lube paste, P/N 12371287 (in Canada, 10953437) or equivalent, apply a light coat around the center pilot of the hub ONLY.

The emphasis on "only" is theirs. The very clearly want you to clean the mounting surfaces and leave them uncoated and dry.

There is absolutely no way the the brake disc is going to move around on the hub with properly tightened lug nuts.

Again, one of the concerns with various "coatings" is that the lug nuts may not remain properly tightened...so there's that. But assuming they stay tight, the problem you've created by reducing the friction between the mounting surfaces is that you've now transferred the rotational wheel loads from the mounting surface friction to the five wheel studs, centered at a point probably at least 1/2" above the wheel mounting surface (somewhere in the middle of the tapered wheel seat depth). So now you've loaded the studs in bending, and they are only designed for tension loads. You risk a stud failure, but more likely you risk deforming the aluminum lug nut seats in the wheels. That would create poor location of the wheels and a greater likelihood for lug nuts to work loose over time. The wheel mounting system is not intended to rely on the studs and lug nuts to resist wheel loadings: they are only intended to initially locate the wheel and then apply a large clamping force to it so that the mounting surface friction will hold the wheel in place.

All of this can found in SAE articles if you have access to them. If not, there are plenty of other articles out there on the topic of wheel attachment.

[NealC]

You missed the entire point and make up scenarios that only exist in you head. You are going off on multiple tangents. You are quite an interesting individual.