Painting Drums

[dmdeaton]

What do you guys paint new cast iron drums with?

[Mitch]

I use black semi gloss rattle can rustoleum

[BudP]

I do the same, for drums and backing plates.

[Jeff/Illinois]

Same here. Lasts a long time too.

[dmdeaton]

Good deal, I will get a few cans tomorrow. Thanks, I was hoping not to get out the spray gun and mix up some expensive stuff.

[Tom Wesenberg]

Just be sure no overspray gets on the braking surface, or you'll have real grabbing brakes.

[Mitch]

Or the car

[MikeK]

If you live in a mountainous terrain or are an aggressive driver then braking can get the drums pretty hot. Some paints will blister. You may want to use hi-temp black barbecue or stove paint. Last set of brakes I did started with a wash of Ospho over the fresh metal followed by Rustoleum 'High Heat' paint.

[Rowdy]

I have also used black brake caliper paint. Bad part is it takes forever and a day to dry. Rod

[Dennis]

I use the Rustoleum high temp black. Before I spray them I clean them with acetone and let dry for about fifteen minutes and then spray on thin coat. Just enough to cover them and they will last a long time.

[CM2]

Painting brake drums reduces the drums ability to dissipate heat...

[BILL WILLIAMSON]

The alternative is RUSTY, UGLY Drums!

[MikeK]

Painting brake drums reduces the drums ability to dissipate heat...

Actually this is not exactly true on two levels.

First, as Bill mentioned, rust. Aside from ugly the rust is porous and full of trapped air, making it an effective thermal blanket.

The paint will provide slower thermal transmission than metal so a thin coat is recommended, as it has little insulating value. If you put gobs, layers and layers on then, of course, you will see some reduction in energy transfer, but still likely less than you will get through red rust.

Second, if you use black paint it will both absorb and radiate thermal energy differently than a reflective machined new drum. Here's what happens (warning- physics geek at keyboard!):

When photons strike a surface they either are reflected or absorbed. Everyone pretty much understands that a black surface will absorb heat faster than a reflective one. Infrared photons are very good at knocking electrons to a higher energy state.

OK, that is the opposite of brake drums- they are already hot and need to dissipate heat. Substances that easily send electrons to higher energy states when they absorb energy are also better at EMITTING infrared photons when the material drops electrons to a lower energy state (cools off). Shiny reflective metal, as well as white paint, do a much poorer job of losing heat by emitting photons than black substances. Ever wonder why all engine radiators are painted black? Try white and see if it cools as well.

[BudP]

Love this web site! Receive at least one observation a day that never occurred to me.

[CM2]

Given the porosity of rust and its roughened surface basically expanding the area needing to be cooled Id say rust is a better cooling media than the smooth paint job....millions of truck and car drums cant be wrong..given the braking dynamics in a model A I'll surrender at this point,odds are if the drums get hot enough to burn off the paint that's the least of your worries..

[BILL WILLIAMSON]

On my scooter, when passing by a BLACK Van, very little reflected HEAT. When passing by a WHITE Van, WAY MORE reflected heat.
Dad Sweating

[Denis4x4]

Just replaced my front drums and had them powder painted red to match the rear drums and wheels. Original powder paint was applied in 1998 and except for some chips on the radius rods, everything looks like new.

[plyfor]

Most of the factory photos show gloss enamel on the drums, etc. We have rocky mountain fronts and standard rears that perform well with the rattle can enamel. We also found that the $1 variety gloss black cheapo from Home Depot gives just enough coverage, and the flat back same stuff is fine for radiators. They are thin enough to allow for touch up without heavy build up.

[BILL WILLIAMSON]

Saw a pic of a touched up radiator. When the Guy laid it on the lawn, looking from the bottom, an Old # 7, race car number appeared! Bet he "wondered" what its' HISTORY was????
Dad Amazed