Removing paint from pad contact surfaces of coated rotors

[The Critic]

The current market trend is to sell fully coated (painted) brake rotors for aesthetic and rust-prevention reasons. During the pad break-in process, theoretically, the pads will remove excess paint from the pad-contact sections of the rotor.

I recently had an e-mail exchange with a product mgr. (not CSR) at a major brake pad manufacturer. The person advised me that their pads are not aggressive enough to fully remove the paint from some coated rotors. As a result, the coating sticks to the friction material and can cause issues. I have personally seen this with a few coated rotors (mostly rears) where the transfer layer will have visible remnants of the silver coating for the first few months.

The person's recommendation was to remove the coating from the rotor surface before install.

Most of these coatings are very resistant to being removed by brake cleaner. Is there a solvent that can remove this coating in an efficient manner?

 

[demarpaint]

A buddy of mine did brakes and rotors about a month ago to his VW and called to ask me what to use to remove the paint. I suggested brake cleaner and very fine steel wool. He gave it a try and reported back it worked well. It might be worth a shot for you to try. Any excess steel wool cleans up easy with a rag and brake cleaner. Make sure you wear gloves.

 

[supton]

Would 60 grit sandpaper work? Something that won't scratch deeply yet enough to lift the paint.

Not sure I am crazy about this fix. I guess it gets out of putting an oiled rotor into a bag, thereby reducing waste?

 

[Bailes1992]

What? So if the pad cant get through the paint then technically the disc would last forever. I'm calling BS.

 

[supton]

What? So if the pad cant get through the paint then technically the disc would last forever. I'm calling BS.

It'd last forever but the pads might not do their job either, which could lead to an accident.

 

[Bailes1992]

It'd last forever but the pads might not do their job either, which could lead to an accident.

I just can't see it. Brake dsics generally wear and get thinner. This is suggesting that the coating is harder than the disc itself?

 

[SHOZ]

I painted my rotors once. Then drove 15 miles. What a waste of paint. Sound to me like the pads are crappy to start with.

 

[supton]

I just can't see it. Brake dsics generally wear and get thinner. This is suggesting that the coating is harder than the disc itself?

Maybe, maybe not--if it scrapes off and then somehow combines with the pad material, it may cause a slippery surface. Like how sandpaper can get clogged with plastic or other debris when sanding something other than wood. Might wind up with paint on paint for all I know. You'd think that'd rub off, but if pad manufacturer is saying otherwise, well I'm not sure to believe.

 

[demarpaint]

Would 60 grit sandpaper work? Something that won't scratch deeply yet enough to lift the paint.

Not sure I am crazy about this fix. I guess it gets out of putting an oiled rotor into a bag, thereby reducing waste?

60 grit will work but it is very aggressive. Steel wool and brake cleaner worked for my buddy as I mentioned. If I were to use sandpaper I'd start with 220 grit, if that didn't work then I'd try 120 grit. I'm pretty sure 220 grit will get the job done, if The Critic decides to go the sandpaper route.

 

[Speedy3861]

I'd try Acetone, or lacquer thinner, possibly combined with fine ScotchBrite.

 

[Astro14]

I just went through this on my son's car. He bought new rotors and pads (I forget the exact brand, major supplier and pads and rotors came from the same company) and the rotors were painted/coated.

The directions from the company simply stated to "drive gently for 100-200KM, avoiding heavy braking".

We didn't have sandpaper, and the coating resisted brake cleaner. We wire brushed the rotor surface but couldn't remove all the coating.

The brakes were unresponsive for a while. They worked, but took excess pedal pressure. After gentle use for a few dozen stops, they got better. 100KM and a few hard stops later, they were great.

The pads worked to clean off the coating, but the brake performance was substandard until the coating was gone.

If I had it to do over again, I would've removed the coating, or most of it, with an abrasive, like 80 grit sandpaper, or steel wool (much finer, but more appropriate - no scratches, and no left over abrasive particles to interfere). Clearly, though, in this case, pad performance was not affected by the coating removal. That may be because the pads and rotors were from the same manufacturer, who, ostensibly, has tested the combination of pad and coating.

The brakes are great now, but for a while, the coating really degraded braking performance and I'm genuinely surprised that the manufacturer didn't say anything about removing the coating.

 

[SHOZ]

Ha, first thing I do with new brakes is go down the road and from around 60 MPH start doing as hard as I can braking to get them things smoking. Then drive home and park it.

 

[atikovi]

The current market trend is to sell fully coated (painted) brake rotors for aesthetic and rust-prevention reasons. During the pad break-in process, theoretically, the pads will remove excess paint from the pad-contact sections of the rotor.

Painted and coated are not the same thing.
1) Painted means just the hat section and the edge.
2) Coated means the whole rotor and the coating is a thin zinc type material that provides less protection than paint. Fine to leave it alone and let the pads take it off.

Maybe that product mgr got confused.

Painted:

Coated:

 

[The Critic]

Painted and coated are not the same thing.
1) Painted means just the hat section and the edge.
2) Coated means the whole rotor and the coating is a thin zinc type material that provides less protection than paint. Fine to leave it alone and let the pads take it off.

The real European rotors (OE, Zimmerman, etc.) use GEOMET on their rotors.

The $20-$40 silver rotors that most folks are buying from Raybestos/Centric/etc are rotors that have been painted with some type of paint....and it is not GEOMET.

 

[dubber09]

Been using and suggesting using coated rotors and never had to remove the coating, it'll be gone in under 100km/60mi of driving (on average).
Just drive and brake as usual considering the parts need to go thru break-in process, that's all.

 

[atikovi]

Coated rotors I put on a Saturn 2 years ago. Didn't remove anything and they brake great.

 

[TeamZero]

Any time I do brakes, I always burnish them in by doing roughly 10 med stops from about 40-50 mph to about 10 mph. Always has cleaned off anything that was on them.

 

[Tomioka]

I'm considering switching to painted rotors when doing brake jobs to reduce burnish times. Many of the newer Toyotas are equipped with painted rotors and I can go with an aftermarket equivalent if I ever do a single axle brake job.

 

[samven]

If you do want to remove it without scratches I would use a fine scotchbrite pad on an angle grinder. I use them to remove carpet glue from the aluminum floor of my bass boat. Takes the glue off and shines the aluminum without scratching it unless you go gorilla on it.

 

[UG_Passat]

The real European rotors (OE, Zimmerman, etc.) use GEOMET on their rotors.

The $20-$40 silver rotors that most folks are buying from Raybestos/Centric/etc are rotors that have been painted with some type of paint....and it is not GEOMET.

Centric-Stoptech GCX coated rotors are partially coated or fully coated, using their "Proprietary" RS2000 coating vs Geomet 360 paint, which happens to be a water-based paint for friendlier manufacturing emissions.

Note that Centric recommends fully coated rotors for abrasive type brake pads and partially coated for adherent brake pads

Centric C-tek are not coated

Centric Premiums, High Carbon and Stoptech drill and/or slotted rotors have an electrostatic coating that is baked on (basically like a powder coat).