Painting Brake Disc?

Tornado · Apr 16, 2022

Thinking to re-paint my original front disc. Have some high temp caliper paint in right colour.
What is recommended method for getting it close to the swept area? Thought I read some years ago to over paint, then use some old pads, maybe with sand paper stuck on, to rotate the disc against, removing unwanted paint. Sound reasonable or do I just muck about with taping off as best I can?

marshg246 · Apr 16, 2022

Tornado said:
Thinking to re-paint my original front disc. Have some high temp caliper paint in right colour.
What is recommended method for getting it close to the swept area? Thought I read some years ago to over paint, then use some old pads, maybe with sand paper stuck on, to rotate the disc against, removing unwanted paint. Sound reasonable or do I just muck about with taping off as best I can?

Taping takes forever. I spray then immediately wipe with a paper towel over my finger dipped in denatured alcohol or acetone after each coat.

Paul (850 Commando.) · Apr 16, 2022

Recently did mine (And forks.), taped them up and it didn't take long because I then used a scalpel to cut off the excess.
Had the "Help" of a good edge that I could use for the trimming, don't know if that applies to yours.

Craig · Apr 16, 2022

Did mine twice , both times taped out ,then cut to ledge with razor , quick and simple ….

acotrel · Apr 16, 2022

Do Japanese motorcycles have painted discs ? Perhaps the right type of steel does not rust as much ?

baz · Apr 16, 2022

acotrel said:
Do Japanese motorcycles have painted discs ? Perhaps the right type of steel does not rust as much ?

Japanese discs are generally painted or anodised
But are not generally iron as the commando is

gforce · Apr 16, 2022

Maybe a liquid mask would work?

AC5217 Maskol 28ml Bottle

AC5217, Maskol 28ml Bottle, Humbrol, Varnishes, No Scale

us.humbrol.com

So just mask with tape around the hub, paint the liquid mask on the rotor to give you a nice sharp line, then peel off the tape to paint it.

marshg246 · Apr 16, 2022

Paul (850 Commando.) said:
Recently did mine (And forks.), taped them up and it didn't take long because I then used a scalpel to cut off the excess.
Had the "Help" of a good edge that I could use for the trimming, don't know if that applies to yours.

Every stock Norton one I've done, the "ledge" is rough, beveled, and often where rust starts. I especially wanted that covered with paint. I used to tape and cut a little back form that ledge but getting a professional look was difficult. My new way is simple and solves those problems.

Tornado · Apr 16, 2022

Seems quite a few videos about showing car guys just painting entire rotor surface, then letting the pads strip away at contact areas. Might just do that and then swap in fresh pads afterwards.

Derek Wilson · Apr 16, 2022

I had mine e-nickel plated - leaves a nice matte grey finish and is extremely durable. Of course the plating wears off of the friction surface pretty much immediately, but 20 years later, no rust, not even from the cross drilled holes. FWIW

ntst8 · Apr 16, 2022

Masking tape and newspaper here, let the paint go very slightly onto the swept area of the disk.
As there was very little paint to remove I just fitted the pads and started riding, that was a few years ago and no problems.

Onder · Apr 17, 2022

You can let the pads sweep off the dry paint but make sure the caliper doesn't collect it or you will be wondering
why the brakes seem unwilling to release. Any chance I know why this happens? Nah....

kommando · Apr 17, 2022

I mount them on a lathe and free to spin in neutral, hold paint brush on edge where I want to paint and slowly hand spin the disc.

Mart UK · Apr 17, 2022

I was thinking similar, but still on the wheel, on the axle in the vice soft jaws. Maybe, then turn the disc round the other way and repeat for the inside.

Dan1950 · Apr 17, 2022

acotrel said:
Do Japanese motorcycles have painted discs ? Perhaps the right type of steel does not rust as much ?

I've decided to try letting mine rust on the un-swept surfaces. After a good even coating of rust is achieved, a 20 minute boil in water will turn the oxide into a different compound and it will be a dark gray after boiling and carding it off with a wire wheel. The non-rusted surfaces will not be affected.

That's the way high end custom guns are "rust blued".

Here is my Dad's 30/40 Krag that I restored using that method.

I know it sounds a bit crazy but I just thought it might be worth a shot. No cost other than a little time and some heat to boil a large kettle of water.

SEd27 · Apr 17, 2022

baz said:
Japanese discs are generally painted or anodised
But are not generally iron as the commando is

Coming from Japanese bikes, the discs seem to be predominately stainless.

Was surprised when looking at options for the Norton that iron seems to be mainstay.

baz · Apr 17, 2022

SEd27 said:
Coming from Japanese bikes, the discs seem to be predominately stainless.

Was surprised when looking at options for the Norton that iron seems to be mainstay.

Back in the day the early 70s Japanese stainless discs were terrible compared to triumph iron disc brakes and to a lesser extent Norton
Guzzi brakes were pretty good by comparison

Tornado · Apr 17, 2022

Many car rotors are still made from iron.

Derek Wilson · Apr 17, 2022

Cast iron is one of the best friction surfaces you can get for standard vehicle use. The use of stainless steel in motorcycle rotors is purely cosmetic, because they are out there for the whole world to see. Nobody wants to see a rusty rotor on their immaculately prepared motorcycle.

I run HH pads with my "stock" cast iron rotor, and it is beautiful, predictable, consistent brake - a bit of rust is a small price to pay.

FWIW

baz · Apr 17, 2022

Derek Wilson said:
Cast iron is one of the best friction surfaces you can get for standard vehicle use. The use of stainless steel in motorcycle rotors is purely cosmetic, because they are out there for the whole world to see. Nobody wants to see a rusty rotor on their immaculately prepared motorcycle.

I run HH pads with my "stock" cast iron rotor, and it is beautiful, predictable, consistent brake - a bit of rust is a small price to pay.

FWIW

When I changed from original stainless discs on my BMW r100 to aftermarket iron discs the iron dust started depositing itself on the front wheel rim!!

Painting Brake Disc?

Tornado

marshg246

Paul (850 Commando.)

Attachments

Craig

acotrel

baz

gforce

AC5217 Maskol 28ml Bottle

marshg246

Tornado

Derek Wilson

ntst8

Onder

kommando

Mart UK

Dan1950

1974 MK II Roadster

SEd27

baz

Tornado

Derek Wilson

baz

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