28plymouthman

Brake drums powder coated

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I sent my brake drums out to be powder coated. 1928 Plymouth with hydraulic brakes. They powder coated the back sides also. Is this car going to stop or should I grind the powder coating off  the  braking surface of the drum.  The car doesn't go very fast. About 40 average. Are the shoes going to cake up or is the car not going to stop because the drums are slick. Any replies are appreciated. Thanks

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if they powder coated the drums where the brake shoes ride the drum, you're not going to be able to stop.

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41 minutes ago, pontiac1953 said:

if they powder coated the drums where the brake shoes ride the drum, you're not going to be able to stop.

My honey says to grind or replace. I agree with her.

Edited by keiser31 (see edit history)

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See if you can find an old time brake shop that can turn the drums. Have them take off the minimum to clean up the drums even if it leaves a few scratches. New drums are getting hard to find, you want to get as much wear out of them as you can.

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Your brake shoes will now be sliding smoothly on plastic.  Even if you manage to get the plastic off the inner friction surfaces, the rest of the plastic coating will probably turn into a gooey mess.  Your powder coat guy should be held criminally responsible for doing something so...'unusual'.

Edited by Real Steel (see edit history)
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2 hours ago, Real Steel said:

the rest of the plastic coating will probably turn into a gooey mess. 

eh? I thought powder coating was basically paint solids applied with static electricity and baked on?

 

Edited by Spinneyhill (see edit history)

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52 minutes ago, Spinneyhill said:

eh? I thought powder coating was basically paint solids applied with static electricity and baked on?

 

 The "paint solids" are plastic dust that fuse together with heat.

 They will also smear with heat. Think slippery!

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Powder coat is polyester powder that is melted on at 425 degrees. As the shoes make contact, the heat produced will melt the poly and get into the shoe and render it useless. Sand the contact area to get back to raw metal. Turning them also works.

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1 hour ago, 28plymouthman said:

Thanks for all the replies. Will have them turned to get back to raw metal.

Asking someone to ruin a brake machine doing something it isn't designed to do takes a set of stones. Bob 

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I doubt the thin layer of powdercoat scraped off the brake drum by a brake lathe will do any damage to the lathe. It's made to grind iron, for Pete's sake. The powdercoating will come off in little crumbs that can be vacuumed up. It won't gum up the works unless you get it hot enough to melt, which won't happen here.

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Are these drums cast iron? If so, the brake lathe will probably do fine. Stamped sheetmetal drums, on the other hand, need to be ground.

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Is it OK to paint the outside of the drum with an epoxy primer?  I'm using SPI two-part epoxy primer that is good to at least 500 degrees.

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27 minutes ago, Luv2Wrench said:

Is it OK to paint the outside of the drum with an epoxy primer?  I'm using SPI two-part epoxy primer that is good to at least 500 degrees.

 

That is how I did my Pontiac.  I had a set power coated and was later informed that the power coating restricted heat dissipation and paint is better.

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I painted mine with 2 coats of gloss  black rust paint and never had a problem. They don't get that hot under normal circumstances. If you want something that is very durable, heat proof and dissipates heat well try black barbecue paint.

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To dissipate heat, thinner and blacker is better. I like Rusty's barbecue paint idea.

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At the speeds you will be gently driving, you do not have to worry about heat dissipation at all.   -  CC

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My Uncle Sam was a boss in the machine shop when they started building those '28 Plymouths. That new Hotchkiss rearend was a big deal. He had some trade magazine pictures of him standing  by an axle on a table.

He told me the first of the cars were built in circus tents. Chrysler only had enough money for production equipment and had to wait for a building. The machines were set and the tents were rented to protect them.

That story was told about 30 years after it happened. #0 years seemed like a lot longer back then.

 

Bernie

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So, poci, did you remove the power coating or continue to use them with no issues?

 

This paint vs powder coating is interesting, as they are both methods to get solids onto a surface, in order to protect or decorate a surface. One does it by dissolving the solids in a solvent and the other by getting the solids onto the surface (static electricity makes it stick while still a powder) and then baking it to make it flow. [Hmm, almost like the OEM reflow paint systems]. There is paint with polyester solids, and there are solids of polyester in powder coating. So why do people make such a big "it is different!" deal out of this? 

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The guy who did the powder coating could have wiped the braking surface with a rag in a few seconds. I guess he didn't know it mattered. Something to keep in mind if you are having brake drums powder coated.

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I don't think that you will have any problems with the powder coating on the outside of the drums, but agree that you should have a bare metal inner friction surface.  I don't think it would be safe to drive with the inner surface coated.

 

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13 hours ago, Frank DuVal said:

So, poci, did you remove the power coating or continue to use them with no issues?

 

I used them as is until the brakes were chattering badly and needed work (NOTE these were the famous 8 lug aluminum drums as seen in the photo.  I am smiling since I had an extra set to replace the originals).  The drums were slightly warped with hot spots and the linings overheated even though I had not driven the car hard or fast.  This could be partially from the powder coat and partially from the finicky nature of these drums but either way a noted 8 lug rebuilder told me the powder coat restricts heat dissipation and my car seems to have had a problem in that area, Todd C. 

IMG_2554.JPG

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I grew up in the AACA, Southern Ohio Chapter, but fell in love with muscle cars while I was in high school. I became a serious street racer in the early 1970's (I know...shame on me!) Anyway, I recall LOTS of us street punks painting our brake drums different colors, so they would look "cool" where you could see them between spokes of our mag wheels. I also recall lots of different brake specialists telling me that this was a bad idea, because the drums would not dissipate heat as well with paint on them. True, we did ruin a lot of brake drums, but I suspect this had a lot more to do with the constant abuse we put our cars through back then (power-braking, burnouts, panic stops when we spied a cop, etc, etc.) 

 

I would never suggest powder coating brake drums, or any other car part which is subject to a great deal of heat. Just my opinion. 

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