1988RedT2 MegaDork
5/5/20 8:48 a.m.

So, is this a DIY-able proposition?  2003 BMW 530i.   Wheels are BMW Style 42.  This is doubtless the car's single biggest cosmetic flaw.   Wifey works at a dealership, so we have access to "wheel guys" that can refinish for a fee.

My thoughts are: 

Why refinish the whole wheel when the center section is perfect?

I've seen guys remove the center section on youtube.  That would give me good access to the damaged area.

Seems like a good bit of corrosion happening under the clearcoat.  Could I reasonably sand that out?

Pics attached.  Thoughts?

1988RedT2 MegaDork
5/5/20 8:49 a.m.

Huh.  Second pic bumped the first pic.

Edit:  Just to clarify, center section is painted silver.  Rim is polished/clearcoated.

Edit#2:  This is probably the best of the four on the car.  The one carrying the spare in the trunk is perfect.

First pic:

¯\_(ツ)_/¯ PowerDork
5/5/20 9:11 a.m.

I have, although I've always stopped short of really polishing since I usually either paint them or accept a brushed look and clearcoat it.  A scotch-brite type abrasive wheel on a drill or a grinder is my primary tool for this.

adam525i (Forum Supporter)
adam525i (Forum Supporter) HalfDork
5/5/20 9:44 a.m.

I wouldn't be afraid to dissemble those and go at the rims, I think those are 2 piece wheels as apposed to something like a BBS RS which is 3 pieces and the two rim halves need to be sealed when re-assembled. I would be doing some research to see if anyone has had any issues with bolts snapping though as they try to remove them, maybe a bit of heat would help if that was the case (not red hot or anything, just enough to release any thread lock in them).  I'd get the tires dismounted before starting on this.

To get rid of that corrosion you are going to need to start with some pretty aggressive sanding and work your way up from there, having some sort of device to spin these  while you are sanding and polishing will make your life a lot easier and get a nice uniform finish. Once these are polished out you will need to stay on top of them as they will not have that protective coating (which failed on you here) to keep the aluminum from oxidizing. 

Toyman01 (Forum Supporter)
Toyman01 (Forum Supporter) MegaDork
5/5/20 9:59 a.m.

I sandblasted and powdercoated a set of BMW wheels. They came out pretty decent. I don't think I'd try to polish a set, but I'd certainly strip and paint them.



Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/5/20 9:43 p.m.

I've done several.  The only way to do it is abrasive if you want to keep the aluminum and not paint.

Start with a stripper to get the clearcoat off.  Abrasives or wire wheels will just melt and smear it.

Then grab a grinder with a light steel wire wheel on it.  You should be able to re-machine the aluminum and get the pits out.  It will leave it looking like the ball-milled finish on a stainless kitchen sink.  If you need to go with a stiffer wheel to get the pits out, go for it, but honestly it isn't necessary.  You'll end up doing two things; you'll cut a divot in the rim, which isn't bad, but if you polish it, it will draw your eye big time when it spins.  It will look like a dent.  The other thing you'll do is just make yourself more work.  Little tiny pits will be visible, but not as visible as a machined divot.

From there, move up to increasingly finer sandpaper, maybe up to 1500 grit.  Switch to a few grades of rouge on a tight-stitch cotton polishing wheel on a drill until you get the finish you want.

I actually skip the clearcoat part.  I keep wadding polish around and every third or fourth time I wash, I just take a few minutes with it to re-shine the polished part and never look back.  Clearcoat caused the issue you're dealing with.  It gets compromised and festers from underneath.  Skip it.  For me, a few minutes every few months is better than this level of repair every 5 years.  Plus, there isn't likely much in the way of home-applied clearcoats that will stick to polished aluminum.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/5/20 9:47 p.m.

This isn't a great picture of the wheels, but they turned out amazing without disassembly. (one piece GTA Firebird castings)  I used the wire wheel/sand/rouge on these lips and then repainted the centers.  This was probably 3-4 years ago and they still shine just like this with a hit of wadding polish.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/5/20 9:56 p.m.

I just dug through some old photos... These were June of 2015.

As I bought them:

This looks like maybe after wire wheel and sanding:

After polishing:

Some of the tools I used:

Aaron_King PowerDork
5/6/20 9:54 a.m.

In reply to Curtis73 (Forum Supporter) :

Thanks for posting those pictures.  I am doing a Pontiac TA with those wheels for the latest model build on here and was going to have to look up how much of the wheel was colored.

ebelements Reader
5/6/20 11:18 a.m.

Pretty sure those are the manner of 2-piece where the center bolts into the hoop, like a Style 5. Should probably be able to pull the center with the tire still on it. Then you can chemically remove the clear, sand out th corrosion, then move up through the grits until you can polish with a drill. That said you'll have to really keep on top of polishing and waxing the polished aluminum as the elements really have their way with it. 

Ideally you'd have the tires pulled, have them blasted, polish the lips, and have them powdercoated gloss clear. They won't be *quite* a s bright as polished raw aluminum but it'll look great and need minimal maintenance.

pirate HalfDork
5/6/20 2:05 p.m.

Well to me the corrosion looks pretty severe. Also appears that there is some kind of a layer that the corrosion has gotten under. Don't know if that is a heavily anodized layer or some kind of paint or powder coat. Whatever the coating is it appears to be cracking at the far left in picture. If it were me I would aggressively media blast to see exactly how deep the corrosion is and how bad it might be under the coating. 



1988RedT2 MegaDork
5/6/20 2:12 p.m.

Just to clarify, yes, there is definitely a fairly thick layer of clear on the stock rims.  There are areas where there appears to be significant corrosion under this layer, and areas where the clear layer is cracked and starting to come off.

Toyman01 (Forum Supporter)
Toyman01 (Forum Supporter) MegaDork
5/6/20 2:30 p.m.

In reply to 1988RedT2 :

The clear coat on the BMW wheels I refinished laughed at paint stripper. It didn't touch it. I ended up sand blasting them.

1988RedT2 MegaDork
5/6/20 3:56 p.m.
Toyman01 (Forum Supporter) said:

In reply to 1988RedT2 :

The clear coat on the BMW wheels I refinished laughed at paint stripper. It didn't touch it. I ended up sand blasting them.

I hear ya.  I haven't done anything to these yet but look at them, and that clear layer looks very thick and tough.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) MegaDork
5/6/20 8:54 p.m.

Blasting will definitely get the clear off, but it will also add significant work to your polishing (if you go that route).  If you're just painting, blast away.  If you're polishing, the sand will leave them incredibly rough and make a ton of extra work for you.

As they are now you can probably do a wire wheel, then 800/1500.  If you blast, you're looking at hours with 120 grit, then 240, then 400, then....

not to mention needing to find some way of protecting the threads in the rim for the center, which for those (apparently) triple-square bolts that probably means threading them back in their holes, which means you'll need all new bolts.

Rocambolesque Reader
5/6/20 9:13 p.m.

One time I bought Porsche "sewer grate" wheels to put on my VW. I decided to polish the outer lip only (the wheels have no dish, it's really just the outer ring around the wheel). I found out the hard way that the wheels were anodized from the factory... I sanded it off with 40 grit, then I did 80, 120, 240, 320, and 400 dry. Then I went to 600 wet and worked my way through 800, 1000, 1500 and 2000. You can imagine my satisfaction when I wiped off the aluminum polish to reveal a mirror-like surface. But yeah, very time consuming and painful on fingers.

pirate HalfDork
5/6/20 9:35 p.m.

Your car your choice. However, the easy button is abrasive blast to uniform finish and then powder coat with a clear or your color of choice. I recently saw some wheels powdered coated  in a gloss charcoal gray that looked fantastic. 

G_Body_Man (Forum Supporter)
G_Body_Man (Forum Supporter) UltraDork
5/6/20 10:57 p.m.

To echo others here, it's a bit time-consuming but pretty easy to DIY. Pop the faces out, hit the lip with a wire wheel to knock off paint and corrosion, go fine and wet on the sandpaper, start with 800 and continue to 2000. Finish up by polishing them to a mirror sheen then hit them with ceramic coat to keep them shiny.

ProDarwin UltimaDork
5/6/20 11:07 p.m.

I have started, but never completed a project like this.  Its an insane time commitment if you don't have sandblasting equipment.  If you want someone else to blast or powdercoat them for you, its often cheaper just to buy new wheels/used wheels in much better condition.  Not sure how that translates to BMW wheels.

1988RedT2 MegaDork
5/7/20 7:48 a.m.
ProDarwin said:

I have started, but never completed a project like this. 

Yup.  That is the one place that I do not wish to be. 

The downside to farming it out is that the car will be off the road for as long as it takes for him to turn them around.  I guess with the current situation, it's not being driven much.  Might be a good time to just bite the bullet.  I think he quoted between 150 and 200 a wheel.  I see "reconditioned" sets for around $1200, 

chandler PowerDork
5/7/20 11:16 a.m.

I posted in the other wheels refinishing thread also but as Curtis said you can wire wheel that clear off. Zip the centers out and start sanding. 

this was my second set and they had that corrosion on the lips under the clear. I didn't re clear them but I washed and waxed them regularly and they stayed really really nice. I'm doing a set of BBS RT that are built like yours right now and meant to take pics but haven't yet.

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