The importance of cleaning aluminum wheel mating surfaces
 

This might seem like an obscure topic but it's very important when diagnosing drive line vibrations or supposed tire balance issues.

I have over the years acquired a lot of second hand wheels that usually are destined for a particular project, and most often what I find is a lot of corrosion on the mating surface of where the wheel meets the brake rotor. It comes not necessarily from the aluminum wheel but from the decomposition of the rotor / drum that it's bolted to.

Recently I bought a set of 17" wheels for the W140 and found that on each wheel the mating surface was loaded with rust from the rotors of the car they came from.

Had I left that corrosion where it was I suspect that it would have caused unwanted vibrations and / or alignment issues of some sort.

When cleaning the corrosion I've found that it's best to use a razor blade and cut the corrosion from the surface while being careful not to cut through the original machined surface. It can be done and does not take too much effort, and you'll know that you've removed enough when you see the original machined surface of the wheel.

Once I've cut the crap off of the wheel surface I use a sanding sponge to clean up and finish. Polish / wax around the perimeter of the area or even over the cleaned surface and you're done.

The same holds true for brake rotors / drums as well, always make sure there isn't a collection of corroded metal on the rotor / drum, otherwise it's tough to say whether the two will mate properly.

If you elect to use power tools to accomplish this task be aware that you can overdo the removal and create a warped surface comparable to the one you're trying to eliminate.

As always, my comments are not a guarantee of success, proceed at your own risk.

steve a

Now I know what I have been missing.. kept on changing my rotors.. I thought I always get a defective one from winhere parts.. this one is really a helpful post. thanks..

When I bought my TD wagon, my passenger rear rim was fused to the rotor via corrosion -took some effort to remove. I then cleaned both mating surfaces and applied a light film of synthetic grease to both to eliminate such problems in the future. This would have been a nightmare on the road with a flat . . . .