rusty brake disc, how to stop it.

[steve_bmw]

i see new ish vehicles on the road with factory discs and the hub part of the disc is still silver and rust free.

they look galvanised?

i am replacing the discs on the z4 and wonderd if i bought oem discs would they have the same protection on them as the ones supplied when the car is new?

when replacing disc's on my last car the hubs went rusty in about a week and looked tatty.

is there any special paint or coating i can use to get that factory protection?

i dont want to brush paint hammerite on that looks rubbish.

thanks

[JonBoy1]

Hi All

New to this part of the forum, been looking for detailing tips and recommendations (post to follow).

Funny that I saw your post today mate, as I was talking to 2 guys I work with, both have new BMW (X5 and 3 series) and I was pointing out the same thing to them (with a big grin as they both delight in mocking me for my boy racer Impreza (which doesnt share this problem).

Smugness over, the spool to the alloy does not appear to be protected at all (from factory) and the calipers on both cars have a similiar tatty appearance.

A mate has recently used block paint from Halfords on calipers etc and has achieved a smooth discreet finish. Might be worth a try

Cheers
Jon

[maniac0796]

OEM replacement Pagid discs come with a special white/grey/silverish coating that gets burnt off with first use. Perhaps it's something along the lines of that?

[mneame]

If it's only the "hub" part of the disc that you're want to keep from rusting then a good mask up when they're new and a coat of satin Hammerite would do the job.

[NotNormal]

steve_bmw said:

is there any special paint or coating i can use to get that factory protection?

i dont want to brush paint hammerite on that looks rubbish.

Get some high temp clear lacquer and spray the parts you want to stay ok, just make sure you de-grease the surface first.

[csbob612]

Zinc primer is what your after. De-grease the hub, followed by 3-4 coats of zinc primer from Halfords, will ensure they stay rust free.

[steve_bmw]

thanks everyone for your help, zinc spray seems to be the best solution.

[steve_bmw]

done the disc's today with some zinc primer, nice finnish too.
used brake cleaner to remove the oil, then applied 4 coats to the hub and the outer part of the disc.
bit of a job to mask off the braking part of the disk, but the paint will scrape off using a stanley blade to leave a nice edge.

[PositronicRay]

Funny thing I noticed today when swapping wheels. I replaced front discs with Pagid before Christmas and they still look good. The rear discs I replaced a couple of months before-hand (not sure of brand came from GSF) look rusty as hell.

Oh well another job for the "when I get round to it" list.

[Byteme]

If corrosion protection is all that is needed then go with something like a high zinc content weld through primer. I have a high lift engine crane attachment coated with this that has sat outside for nearly 30 years between uses and still looks like new.

Would I use this type of product on a brake disc hub? Only if I could guarantee never to get them hot enough to melt off the zinc!