Dealing with rust?

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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Dealing with rust?

Post by Del »

The bottom, inside edges of my sills are showing some rust which seems down to them getting “sand blasted” by spray from the wheels. Over years of motoring and DIY, I must admit I’ve never been much good at successfully dealing with rust. I’ve tried to treat these sill edges in the past, but the rust just seems to come back.

When the Spring and better weather comes :D I was intending to take the sills off and attempt to treat the rust again. Any rust treating experts out there? Is a Zinc primer the way forward or a base coat of Etch primer?
Jonco
Joined: Sat 04 Jun, 2011 07:24
Posts: 402

  Z3 roadster 1.9
Location: Cheshire

Re: Dealing with rust?

Post by Jonco »

I share that feeling Del. Did mine 18 months ago - Kur-rust (?), Zinc oxide primer and then Hammerite. Front edges are showing signs of rusting again already :head:

Some sort of edging strip might work - I recall there was a thread the other week discussing this concept.
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TomH84
Joined: Sun 15 Dec, 2013 15:22
Posts: 113

  Z3 roadster 2.2i

Re: Dealing with rust?

Post by TomH84 »

I highly recommend Bilt Hamber products. Their cavity sprays are unbelievably brilliant. They also do an excellent range of rust converters and anti rust primers. Far superior to rivals. Reasonably priced and UK made. I've used their entire range on my classics for years with great results.

http://www.bilthamber.com/corrosion-treatments

http://www.bilthamber.com/cavity-waxes

Britain invented rusty cars. Great that we got the solution sorted too :lol:

I'm also into detailing and have used their clay bars, polishes and waxes. Again, all first class.

Just my 2 cents.
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PFL969
Joined: Fri 29 Jun, 2012 10:07
Posts: 79

  M roadster S50
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Re: Dealing with rust?

Post by PFL969 »

Have you tried Dinitrol?
Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Dealing with rust?

Post by Dino D »

Just had a look at Bilthamber. Impressive stuff
Need to do some rusty sills. I think the gel will be the best for that job.
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: Dealing with rust?

Post by Southernboy »

I'm surprised that you guys don't do the electroplating thing...Over here it isn't an especially expensive process. I would have thought that if you're going to the effort of removng the sills, it would be best to take the part to a plater, they do the cleaning / stripping and prepping before dunking it into the zinc solution for plating. No doubt that the electroplating will get in everywhere and provide the best protection possible. Next step would be to have the part powder coated in an "undercoat" finish, which also gets into every nook and cranny, and finally take it to the paint shop for colour and clearcoat. You shouldn't have to worry about rust for the next 15 years or more. Probably quite a financial investment, but one which will give you a return even if you sell the car - rust free !
We all know that powder coating is about as tough a coating as one can apply. It is resistant / impervious to all known solvents and the only way to remove it is sand blasting, add to that the electroplating with zinc and I would reckon you're about as protected as you can be, short of having plastic or fiberglass sills.
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John Wilson
Joined: Fri 12 Jun, 2009 12:11
Posts: 252

  Z3 roadster 2.0
Location: Diss

Re: Dealing with rust?

Post by John Wilson »

I'm wondering if DIY electroplating could be a possibility. It would be hard to do a whole sill because of the size of bath needed, but with quite a small bath you could dip the front edge in , where the rusting problem occurs, bung in the chemicals and a bit of zinc, attach a car battery charger, and there you are. How hard can it be.
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Southernboy
Joined: Thu 07 Oct, 2010 12:39
Posts: 6436

  Z3 roadster 3.0i
Location: Johannesburg

Re: Dealing with rust?

Post by Southernboy »

I think it's a tad more complicated...I think the solution it is immersed in has some specific properties which make the process effective. Also, I think there's some prepping to be done before hand too... :wink:
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John Wilson
Joined: Fri 12 Jun, 2009 12:11
Posts: 252

  Z3 roadster 2.0
Location: Diss

Re: Dealing with rust?

Post by John Wilson »

I think its zinc sulphate solution they use. Im sure it must be all on youtube. The thing is about electroplating is that as long as zinc is deposited, it will oxidise preferencially to the steel. Some steel hulled boats have a big lump of zinc bolted to the hull for that reason. It sets up like a big battery in damp conditions and the zinc gradually corrodes instead of the hull.
Therefore, even if the preparation isnt perfect, it still should be effective, unlike paint preparation.
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