Rust on Break Rotor (inside)

[MrTookies]

Hi there,

I took my wheels off intending to do a break fluid change when I encountered rust on the spot where the wheels mount (not sure what that's called).
Also found out the 3 of my wheels have a black cap there and one is missing not sure what happened there...

Don't really understand why it can rust that much with the car being in the garage everyday...

Does anybody know what the best solution is for mitigating the rust? Get a rust remover, sand it and paint it?

Does anybody know what that cap is called, I'm sure it serves some purpose... Would like to get it replaced.

Thanks!

[turboawd]

Those hubs are part of your wheel bearing assembly. They rust as moisture gets trapped behind the wheel caps. Put some grease on the hubs before you put your wheels back on.

[Maverik259]

Hit em with some sanding or a dremel to remove rust and then ya apply grease before putting rims back on.

[Teufelshund]

Just had my wheels refinished due to corrosion around the center caps (my dime). I've got replacement center caps on the way (dealer's dime) so I told the powdercoater he needn't bother putting the old ones back on.

Consequently, I was able to see what lurked behind the caps when I picked the car up. I was monumentally astonished to discover that a three-year-old bimmer with less than 50K miles sported axle nuts that looked like they belonged on a troop carrier in the cargo bay of an aircraft carrier which was sunk at Midway during WW2.

I'll attach an image of one of the caps and a couple of the nuts for your viewing pleasure.

[Maverik259]

Yup same thing on my 2014 with 36k miles. This is certainly what's causing all the corrosion in our wheels. I went through with a wire drill grinder attachment to grind all the rust off my hubs, rotors, calipers, and inside of the wheel wells. I then subsequently painted all the surfaces and clear coated them as well as put heavy duty grease on the nuts you have shown to prevent it completely in the future. This also caused my back wheels to be frozen on due to this rust. Had to beat them off with a small sledge and 3 blocks of wood that I kept breaking due to how hard I had to hit them.

I recommend you take the time to do the same or your money will be wasted.

[turboawd]

Not sure why bmw designed the cap so tight. Let's moisture in but doesn't let air breath behind cap to dry it out.

[1norseman]

My caps looks the same, at first I thought someone tried to pry them out.
But no damage on the wheel itself, so not pried. (Poor design by BMW, if the caps go bad this easily) Luckily my hubs are fine.
Just disappointing that BMW's can get rusty nuts this soon, when not even close to retirement age..

[Maverik259]

Originally Posted by 1norseman

My caps looks the same, at first I thought someone tried to pry them out.
But no damage on the wheel itself, so not pried. (Poor design by BMW, if the caps go bad this easily) Luckily my hubs are fine.
Just disappointing that BMW's can get rusty nuts this soon, when not even close to retirement age..

If the caps clear coat is deforming then you have oxidation occurring. I would take measures to prevent or remove from the inside now. Remove your wheel I bet you'll find something whether on the hub, the lip, or the inside of the wheel where the cap goes.

[1norseman]

Originally Posted by Maverik259

If the caps clear coat is deforming then you have oxidation occurring. I would take measures to prevent or remove from the inside now. Remove your wheel I bet you'll find something whether on the hub, the lip, or the inside of the wheel where the cap goes.

True, good suggestion.
Nonetheless, if the caps are sub-standard quality, it won't take much for them to start oxidizing.
I have on my older BMW, centercaps that are 10yrs old if not more, and they are still fine, despite rust behind them. Switching to a new a supplier, or new environmental regulations can create issues not anticipated.

I'm planning to paint the ugly brake shields soon, adding to check for this too.
When I installed the spacers last year, I didn't see much rust, but I wasn't really looking for it..
I will definitely this time!

[Teufelshund]

Originally Posted by Maverik259

This also caused my back wheels to be frozen on due to this rust. Had to beat them off with a small sledge and 3 blocks of wood that I kept breaking due to how hard I had to hit them.

I recommend you take the time to do the same or your money will be wasted.

Wow. First chance I get, I'm asking the powder-coater if he had issues removing any of the wheels. You'd think he would've mentioned something like that.

Regardless, I'm following your recommendation to protect the investment and prevent further damage. As it is, there's no way that axle nut could ever be removed without extreme measures (torch/grinding wheel... or wait until the rest of it rusts off).

The sobering thought is, if that's what I can see, what the hell is happening inside the places where I can't!

[mrfochon]

Is that not covered in the warranty ?

[Teufelshund]

Originally Posted by mrfochon

Is that not covered in the warranty ?

Dropped by the service department this evening to inquire about that very thing (it's a CPO vehicle). I kid you not - the manager squatted down, took a look, and asked "Which nuts are you talking about." I said "The ones that used to be right where you're looking."

He pulled the car's history and went on about how it'd lived it's entire life in NY. Terrible weather, blah, blah, blah. The bottom line is he basically blew me off and said it was an expected cosmetic issue which wasn't covered.

PS - They also reneged on replacing the center caps after realizing I purchased the vehicle from another BMW dealer. Said they should've been replaced during the CPO inspection and I ought to go back and "have them make it right." And I'm just too damn tired to be mad.

[mrfochon]

I also in NYC. Not fan our the store here.
Just got ripped off for buying the table and it is missing a part. Just saying.

That being said my two back wheels have the rusted issue as well. And some early corrosion can be seen.

I have an extension of maintenance and warranty for another year.

Not sure how I'd fight this one

Will keep you posted as soon as I go.

[Maverik259]

Originally Posted by mrfochon

I also in NYC. Not fan our the store here.
Just got ripped off for buying the table and it is missing a part. Just saying.

That being said my two back wheels have the rusted issue as well. And some early corrosion can be seen.

I have an extension of maintenance and warranty for another year.

Not sure how I'd fight this one

Will keep you posted as soon as I go.

BMW of NA is replacing Wheels with corrosion for people under warranty. It's been documented. If your SA denies it then tell them you want it escalated.

[Russmov]

Originally Posted by Maverik259

BMW of NA is replacing Wheels with corrosion for people under warranty. It's been documented. If your SA denies it then tell them you want it escalated.

So, funny story, off topic as well, I had some shadowline trim pieces replaced, and I was trying to get them all done. BMW originally said yes to replacement, so the dealership went ahead and replaced the back window pieces , I was trying to get the rest done, turns out bmw WONT cover them, AND refused to pay the dealership for the work they did. Needless to say, BMW is picking and choosing what they will cover, and for who. I've had my rims refinished under warranty, while others have them replaced. Very fishy