Plating rotors


#1

I just had a talk with someone who suggested plating brake rotors. I can see the sense if you mask the braking surface, but what about plating the whole thing? I assume that plating on the braking surface is a bad idea, but I don’t really know the reason.

UPDATE : I don’t care how pretty or showy the rotor is. I care about preservation of the rotor. I also understand that the braking surface just that - a braking surface, and is not meant to be plated, however, if I drop it off at the platers, and they dunk the whole thing in, then the brake pads will get the plating all on them from that surface which sounds bad to me, but what do I know. another comment is about powder coating compared to plating - I am still interested in that too.


#2

Like… Chrome plating? I have no idea why you’d plate a rotor unless you wanted to make it shiny for a show car that never gets driven. The pad would rip the plating right off, and you don’t see most of the rest of the rotor, so it’d be a waste of money.


#3

Plating is a conformal coating. It does not become part of the base metal. Differences in thermal expansion coefficients would probably cause adhesion failure.

But I’m guessing. I’ve never heard of it done, but if you decide to take the financial risk and try it, let us know how it works.


#4

Never heard of that. People paint their calipers and might paint the hub, but a rotor needs a directional pattern on the surface that the pads contact to provide braking and good wear of the pads.


#5

Not done, ever, as far as I know, for a car that is actually driven. I can’t imagine chrome would be a good braking surface.


#6

If you will try a plating, I’d suggest hard chrome or electroless nickel but consult with a metallurgist first if you can find one. Chrome does not deposit uniformly; has a tendency to build up more at sharp corners so it may need to be cut back in an appropriate place where the disk rests against the hub unless you will mask the part. Electroless nickel deposits uniformly. A soft, less abrasive and therefore faster wearing brake pad material might be advisable to preserve the plating. You might be exploring in an area where vehicle makers have already been but ended up using what you have now as a good compromise considering cost, braking performance and brake life.


#7

Wha Who has made some excellent points. Any electrodeposited metal will deposit thicker on the edges due to higher field density.

Another thing I wondered was whether the plated finish would provide sufficient friction. There’s a reason disc surfaces are not polished…

I’m curious, OP, what’s your goal in doing this?


#8

Don’t do it. It’s that simple.


#9

I am interested in preventing corrosion on a daily driver, not show car art.

My rotors new have a gray primer on the non-braking surfaces that easily comes off if brake cleaner touches it. I noticed Hyundai has new rotors with a tougher coating on the hat.

Plating services - and powder coating - are cheaper by batch, so there’s a tendency to get the kitchen sink involved.


#10

I’ll echo @texases here. “Don’t do it.”


#11

Are you sure that’s primer and not a protective coating for shipping & storage?

The bottom line is that I think this is a bad idea subject to failure.
The good news is that rust on brake discs is perfectly normal and poses no problem as long as the vehicle is used routinely such that it can’t evolve into rot and as long as the vehicle isn’t stored with the parking brake on such that the pads can marry themselves to the rusting disc/drum. Using the parking brake is a good thing. Leaving a vehicle unused for a long time with the parking brake engaged is a bad thing.


#12

thanks to all, yes I follow all these points. It would seem that if a common car manufacturer does something to the rotor to prevent corrosion, it must have some practical merit.

then again, I never want to do again what I had to do to get the rotors off in the first place - I am onboard with good maintenance over “doing something” to the rotors.


#13

Manufacturers have wanted to plate rotors with SOMEthing to prevent rust buildup under open wheels and to prevent “lot rot” on cars sitting and waiting to be sold. No good solution has been found. Good 'ol gray cast iron is a great rotor material. The friction surface must be a bit rough so a transfer layer from pad to disk forms. That layer helps stabilize the friction coefficient under braking but it isn’t a corrosion protection layer. Some aftermarket rotors come with epoxy or powder coating on the hat section so it stays pretty under open wheels. A couple suppliers zinc plate the rotors so their dimples, holes or slots stay relatively pretty. The zinc wears right off the friction surface. ANY plating on the friction surface is bad for brake performance since the rotor is supposed to wear.

The best thing I’ve found to keep your rotors pretty under open design wheels is take brand new rotors, clean the surface with brake-cleaner, paint with high ceramic content caliper paint. Paint the hat and edges, don’t mask the friction surface but don’t spray it heavily either. Then cook them in the barbecue grill for a half hour at high heat. A little anti-seize on the back-side and install. Bed the brakes by driving around the block with light applies, let cool, repeat, let cool. You will have pretty rotors for a year or so in the salty midwest. Minor touchups when rotating tires and that’s the best you can get.


#14

@the_same_mountainbike said “Are you sure that’s primer and not a protective coating for shipping & storage?”

yes

well, no, but if you mean the layer of oily material on the braking surface that I cleaned off using brake cleaner, then yes.

but this gray primer was coming off if it was hit with brake cleaner. I figure if it has this lousy coating as-is, why not try to improve it if I can.

it might be a losing battle to keep up the anti-corrosion surface. there are other battles.


#15

I don’t understand how rotors can corrode for a daily use car. The SECOND you brake any surface rust is scraped off. I can understand a vehicle that’s been sitting for months at time…might have this problem…but NOT a daily driver.


#16

I’ve purchased aftermarket rotors which came “coated” with some kind of paint/coating. It immediately wears off the friction surface, but was supposed to keep the rest of the disk from rusting.
I think the color is sought after by certain enthusiast groups; like the ones who paint their calibers.
The real question no one is asking is why? What are you trying to accomplish? Are you trying to save thin rotors, or improve the friction surface, or just add color?


#17

I already asked “why”. The reason is strictly aesthetic.
That coating you mention is a rust preventative. It’s supposed to be cleaned from the surfaces when the rotors are installed. All rotors come with it to prevent rusting during shipping and storage in inventory. Failure to clean that coating from the surfaces can result on uneven friction and brake pulsing.


#18

IF
you are seeing those colored rotors ( and sometimes calipers too )which can be seen through the wheels on spiffed up cars…
Those are powder coated ( or sometimes merely painted ) , not plated.
and never the friction surface.


#19

I updated my question to address some responses, thanks to all. It is sounding like I’m going to leave them alone.


#20

This came up a while back and I posted about specialty rotors that are coated to prevent corrosion but it’s primarily for show cars.

Check this out- http://media.gm.com/media/us/en/gm/news.detail.html/content/Pages/news/us/en/2011/Nov/1130_fnc.html