Wheels/Tyres: Why do our alloys seem to corrode from the inside out ?

[krussel]

I have recently started to refurbish my BBS alloys and noticed that on the inner rim they seem to be corroding from the inside outwards. The paint seems to bubble up. Once you scape the bubbled surface off is pure white powder underneath.

On another thread we were debating why this happens and we were wondering if using copper grease on the hub makes it happen ?

Here are some pics.

















I know I am missing a wheel nut but I was just moving the car out of the garage.

So any idea why the wheels corrode inside out.

[Luxobarge]

Brake dust is quite corrosive. If we were all to clean the inside of the wheels as often and thoroughly as we do the outside, they wouldn't corrode as fast as they do.

But that would be a real PITA eh?

[krussel]

Still seems to bubble from the inside though and not through the paint ?

[Adman]

Originally Posted by krussel

Still seems to bubble from the inside though and not through the paint ?

My first post.

Hi I had my wheels off last weekend & noticed the bubbling, I have thought about spaying them in Silver, what is the best way to achieve your results?

Cheers

Mike

[brickman]

Brake dust is probably what causes it.

On cars without monster brakes you can easily get a brush in there and clean them from time to time. Gentle degreaser like Muc off/Sh1t shifter/Jizer is what you want.

The white powder used to be part of your wheel, its corroded and broken down away from the healthy metal. Ideally you need to blast/clean it to bare metal and then seal it with paint or what ever.

I wouldn't worry , unless they are very high performance/super light wheels and you are using them on a track they aren't exactly going to fail on you!

[timpy]

We were talking about the use of copper grease in another thread and someone posted up that the use of copper grease could promote corrosion between dissimilar metals and perhaps shouldn't be used in such cases.

Galvanic corrosion being a big topic, and it not always manifesting itself as you would expect, prompted krussel to post this thread to see if collectively, we knew any more about it as a subject, and could it explain the corrosion on his wheels, or at least throw a bit more light on how and where it can happen or is important to try to prevent in cars.

Wheels look great with the smooth hammerite by the way

[krussel]

Originally Posted by Adman

My first post.

Hi I had my wheels off last weekend & noticed the bubbling, I have thought about spaying them in Silver, what is the best way to achieve your results?

Cheers

Mike

Hi Mike and welcome.

I have done a few wheels over the years with nothing more than rattle cans.

The backs are easy as you roughly rub down and give it a couple of good coats of smooth spray hammerite.

To get a good finish on the front side is mostly about patience. First step is to get a bit brutal and using a flat blade screw driver scrape off all the bubbling paint and the white corrosion underneath. Then take some 240 grit wet and dry paper and rub it back to clean metal. If you want the best finish possible you need to add a light skim of body filler and flatten it back.

Where the paint is intact you can get away with rubbing down. I find a med wire wool works best and is cheap. Wipe the whole wheel with metholated spirit.

Once you satisfied mask out the tyre and give the wheel a light coat of grey primer. This will show up if you need to rub down some more.

Once happy apply 3 light coats of cello silver spray allowing each coat to dry. What you want to avoid here is any runs.
Once dry wipe around with more spirit if needed and apply a coat of clear Lacquer to seal the paint. Go easy as it runs if too heavy.

That's about it. Easier to achieve in the summer. This time of year I sprayed mine in the shed using a heater to warm the wheel first. I also place the spray cans in some warm water for 10 mins.

[Adman]

Thats fantastic a real help just what the doctor ordered many thanks for your time & trouble.

[krussel]

Originally Posted by Adman

Thats fantastic a real help just what the doctor ordered many thanks for your time & trouble.

No problem Mike is what the forum is all about. Fixing our cars and getting ideas.

I used Halfords silver wheel spray. I found that the wire wool and wet and dry paper was much cheaper on Ebay funny enough.

[Adman]

Originally Posted by krussel

No problem Mike is what the forum is all about. Fixing our cars and getting ideas.

I used Halfords silver wheel spray. I found that the wire wool and wet and dry paper was much cheaper on Ebay funny enough.

You have now completed my wish list with Halfords Silver Etc.

I agree about forums I am a member of TR Register & it has helped me out no end over the past 11 years.

Cheers again.