Rotor alloy diamond cut corrosion?

[Slowroger]

Hi all,

I've noticed all 4 of my alloys have what appears to be corrosion on the diamond cut part edges. I want to be sure if it's just the clear coat failing or actual corrosion. I haven't kerbed any of these alloys and there are no kerbings at all on any of them.

I've done some searching about but can't quite find a clear cut answer on remedying this without paying out the *** for a refurb. If it is corrosion, is this something I could repair myself with 180 - 2000 grit sandpaper and metal polish? My main concern of doing that is it appearing again after maybe a week and having to keep on top of polishing every so often - I can't get a clear answer on clear coating it either, some say it wont bind to the bare metal? Lastly, if I chose not to clear coat it, do you believe the wax protection properties from the metal polish would suffice?

Advice appreciated! Cheers

 

[Buxton2901]

This is a common issue with the diamond cut Audi wheels unfortunately. I have had mine powder coated satin black which is a much more durable finish.

A refurb is the only real way to bring them back to life. I wouldn't go at them with sand paper of I were you

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[feva]

This is a common issue with the diamond cut Audi wheels unfortunately. I have had mine powder coated satin black which is a much more durable finish.

A refurb is the only real way to bring them back to life. I wouldn't go at them with sand paper of I were you

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Oh pics of stain black wheels if you please.

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[Buxton2901]

Some attached to wet your whistle

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[feva]

Some attached to wet your whistle

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Very nice

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[--AUDI--]

https://www.audi-sport.net/xf/threads/diy-refurb-on-diamond-cut-rotors.387110/

Have a look at this, I have just done mine myself but you would need access to a large lathe

 

[ld2130]

@Buxton2901 with those wheels have you thought about going full bling with a set of these (black discs)?
http://www.blackdiamondperformance.com/

 

[RS3 S.]

I love the diamond cut finish on modern alloys but it does take some caring for. I wonder if a strong acid type wheel cleaner is to blame as you state no visible damage to the rims?.

 

[Buxton2901]

@Buxton2901 with those wheels have you thought about going full bling with a set of these (black discs)?
http://www.blackdiamondperformance.com/

These do look rather cool . Going to do the calipers when I have a spare weekend

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[Slowroger]

I love the diamond cut finish on modern alloys but it does take some caring for. I wonder if a strong acid type wheel cleaner is to blame as you state no visible damage to the rims?.

I think this may be the likely scenario. I first noticed it after I had it serviced and they did wash it.

If it is from an acid based cleaner what is the best way to resolve? Or is this a strip and respray of clear coat job?

 

[feva]

I use PH neutral cleaner only way

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[Buxton2901]

I use PH neutral cleaner only way

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Yep this.
Bilberry wheel cleaner for me.
Although I will be trying bilt hamber next

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[feva]

Yep this.
Bilberry wheel cleaner for me.
Although I will be trying bilt hamber next

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Bilt hamber is very good, but very expensive

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[CHEZ]

Aaaaah ze old white worm.
Comes with the territory of diamond cut wheels afraid

 

[RS3 S.]

I tend to use any ''acid free'' wheel cleaner & having had 3 cars with the diamond cut finish never had a problem BUT i tend to keep on top of my wheel cleaning & only really need to use a wheel cleaner if i have done a load of miles like after a big road trip.

 

[Slowroger]

So I tested some metal polish on it today and the cloth turned black which tells me there's no clear coat on the diamond cut parts. I've managed to get 80% of the marks off by hand - Will try again with an electric polisher at some point and then seal it. Cheers for the advise here though chaps.

 

[Marky007]

Anywhere in north east anyone can recommend mine need done ?

 

[feva]

RS alloys in Hartlepool I think has a lathe to trim off damage on polished faces
Had a few set of wheels powered coated by them

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[Buxton2901]

Anywhere in north east anyone can recommend mine need done ?

Bettablast in shiremoor are great.
If your wanting them powder coated

Avoid the alloy wheel specialist is cramlington. They were the ones driving my car around whilst they were supposed to be doing my wheels

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[Marky007]

RS alloys in Hartlepool I think has a lathe to trim off damage on polished faces
Had a few set of wheels powered coated by them

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Just got off the phone to them £80 a wheel so will be getting booked in there soon day and half turn around

 

[Marky007]

Bettablast in shiremoor are great.
If your wanting them powder coated

Avoid the alloy wheel specialist is cramlington. They were the ones driving my car around whilst they were supposed to be doing my wheels

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Thanks for that will steer clear from them

 

[feva]

Just got off the phone to them £80 a wheel so will be getting booked in there soon day and half turn around

Decent bloke Ray

Loads of different finishes, some are

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[DickoB8]

I was possibly unlucky but I had RS do some BBS RC’s on a previous car and the finish was average one wheel was that bad I had them redo it. I am very particular don’t get me wrong but in places especially in between the spokes had uneven coverage. They have possibly upped their game as that was a good 3 years ago!

 

[Marky007]

I was possibly unlucky but I had RS do some BBS RC’s on a previous car and the finish was average one wheel was that bad I had them redo it. I am very particular don’t get me wrong but in places especially in between the spokes had uneven coverage. They have possibly upped their game as that was a good 3 years ago!

Really were those diamond cut alloys

 

[feva]

I was possibly unlucky but I had RS do some BBS RC’s on a previous car and the finish was average one wheel was that bad I had them redo it. I am very particular don’t get me wrong but in places especially in between the spokes had uneven coverage. They have possibly upped their game as that was a good 3 years ago!

Oh? I've had quite a few sets of wheels done with no issues and also a few mates. Use to get winter tyres for my bmw put on there as well as they take great care.

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[DickoB8]

Really were those diamond cut alloys

No they were just powdercoated BMW grey, like I say I was possibly unlucky

 

[CarbonMike]

So I tested some metal polish on it today and the cloth turned black which tells me there's no clear coat on the diamond cut parts. I've managed to get 80% of the marks off by hand - Will try again with an electric polisher at some point and then seal it. Cheers for the advise here though chaps.

If theres no clear coat i might bust out some Autosol aluminium polish on one of mine then!

 

[Meemo]

I always thought there was a clear coat! the more you know.

I do allot of miles in mine on heavily salted roads, so last winter I ceramic coated the diamond cut surfaces in CquartzUK edition which protects for 2+ years, was £30 or something near that, took 5 minutes to apply (after cleaning with iron out) and they have withstood the winter. I regularly drive coastal routes too.
100% recommend using a ceramic coat after you have all polished back just to keep them protected

if you did not curb them, could be just stone chips and salt damage. Glad you was able to lightly sand it out!

 

[CHEZ]

Pretty sure diamond cut wheels are coated in laquer mind, aka clear coat.
They are not bare exposed metal.
They would be white after the first salty bath if they were not coated in something

 

[Meemo]

Pretty sure diamond cut wheels are coated in laquer mind, aka clear coat.
They are not bare exposed metal.
They would be white after the first salty bath if they were not coated in something

Second that, I was under the impression they had a clear coat, saw a comment further up saying they couldn't be clear coated which did throw me a bit, surely no different to painting in a flat colour over the top.. just it is clear.. Perhaps they mean the clear coat over diamond cut will not hold as well due to the surface being slick which makes more sense.. hence the fact they regularly corrode if not treated with a ceramic or similar.


definitely do a clear coat and ceramic coat if you have sanded back then I would say

 

[CarbonMike]

Pretty sure diamond cut wheels are coated in laquer mind, aka clear coat.

Oh for sure, i was under that impression also!

Maybe there not after all??

 

[CHEZ]

Oh for sure, i was under that impression also!

Maybe there not after all??

Well, this is the thing.
A diamond cut finish should be laquered, coated etc, and in general they are, however, because it's lovely shiny bare metal, there isn't much of a key for the treacle to key to, so it's often very thin at best, patchy mostly.
Removing the protective coating with an abrasive polish in my opinion is a slippery slope of a quick fix.
If that makes sense.
Polishing is only going to remove more of the already Spartan protective layer

 

[feva]

Had the wife's alloys done at RS today. She'd been in a bump a couple of weeks ago. The repair centre used Motorcool at Stockton-on-Tees. The colour match was awful, didn't like the finish either.
So they offered to redo it. Told them I wanted it done at RS. So they paid for one, so why not get the rest done? Went from standard audi grey to dark anthracite mix colour. Absolutely over the moon with them. The shade looks slightly different from different angles. Transformed the look of the car.

Getting my a4 rotors done later in the year definitely to gloss black with polished diamond edge.

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[spartacus 68]

Get them powder coated. My wife's BMW i3 REx has diamond alloys and two of the wheels were refurbished by The Wheel Specialist. Now bear in mind this was wheels with no kerb rash, and they are summer wheels only with a full set of powder coated winter wheels which go on in November. I was late getting the summer wheels on this year, so was genuinely surprised to see white oxidisation starting to appear.

It's a waste of money trying to keep on top of it. Our climate does nothing to stop the wheels deteriorating, so unless you have to have them factory finish, then powder coating is the way to go. Incidentally you can only diamond wheel cut them 2-3 times anyway.

 

[Daves1972]

If theres no clear coat i might bust out some Autosol aluminium polish on one of mine then!

I know this is an old post , but did you go down the route of Autosol then ceramic coating the diamond cut ?